Electroacupuncture: an introduction and its use for peripheral facial paralysis

By: Mayor, David F.

Abstract
Acupuncture and electrotherapy interface in the practice of electroacupuncture (EA). This article introduces some of the basic concepts and terminology of EA, its advantages and electrical parameters. The aetiology and incidence of peripheral facial paralysis (PFP), its pathology and prognosis are then covered. Conventional treatment of PFP is briefly mentioned, followed by a more detailed discussion of Western electrotherapy for the condition and the evidence for its clinical use. Background information on manual acupuncture (MA) and PFP is given. The literature on EA is reviewed, and EA treatment is then described according to the stage and severity of paralysis. Comparisons between EA and other modalities and combinations with ancillary methods are outlined, and the acupoints and electrical parameters used are analysed in some detail. A final discussion summarises some suggestions for safe and effective treatment. This article is based on the chapter on peripheral motor disorders in the author's recently published textbook on electroacupuncture, (1) together with material from the clinical studies database at wwww.electroacupunctureknowledge.com and an internet trawl of recent research.
Keywords: Acupuncture, electroacupuncture, electrotherapy, Bell's palsy, facial paralysis, neurapraxia (neuropraxia), neurotmesis, nerve, muscle, stages, motor point, denervation, tetany, clinical studies database, superficial needling, point-to-point needling, synkinesis, contracture, exercise, heat
Electroacupuncture, electrotherapy and peripheral facial paralysis--the background
Electroacupuncture: an introduction
Acupuncture and electrotherapy interface in the practice of electroacupuncture (EA). Here this is defined as the electrical stimulation of acupuncture points (acupoints) through needles. After the needles are inserted and deqi obtained in the usual way, electricity is passed through pairs of needles to give a continued stimulation, usually for 20-30 minutes.
Related treatments include probe or point TENS (pTENS, electrical stimulation using a small diameter handheld probe) and transcutaneous electrical acupoint stimulation (TEAS, stimulation of acupoints via surface electrodes). Another approach is laser acupuncture (LA), the application of low intensity laser light to acupoints, either transcutaneously or through an inserted hollow needle. pTENS, TEAS and non-invasive LA are useful if patients find needles unacceptable, although their effects are not identical.
EA is applied at the same points as traditional or manual acupuncture (MA), and has been used for most conditions for which MA is indicated, especially when manual stimulation has not brought a response, or when strong reduction is appropriate (e.g. for severe or acute qi and/or blood stagnation). It is less commonly used in deficiency conditions.

Like other forms of electrotherapy, EA is particularly indicated for pain (as in painful obstruction [bi] syndrome), paralysis (both flaccid and spastic) and muscle wasting (as in atrophy disorder [wei syndrome]). It has beneficial effects on microcirculation, inflammation and nerve damage. (1)
Advantages of EA include:
* EA is more effective than MA in some situations, and often potentiates the effects of traditional methods, particularly when strong, continued stimulation is required, as when treating paralysis or some forms of pain. (2)
* EA can be less time consuming and less demanding of the practitioner than MA, in both training and practice.
* Results may in some cases be more rapid, (3) and longer lasting. (4)
* EA may have specific effects on pain, relaxation, circulation and muscle that are different from those of MA. (5)
* EA is more readily controlled, standardised and objectively measurable than MA.
* Non-invasive stimulation methods can also be cost effective for home treatments, perhaps between sessions with a practitioner, although some forms of treatment will require supervision.
* EA allows stronger, more continuous stimulation than MA, (6) and with less tissue damage.
EA differs from MA in several respects (see table 1):
The parameters of EA
The electric current used in EA has various characteristics: polarity, frequency, amplitude/ intensity, mode, pulse duration, waveform.
Polarity (and pulse duration)
Current should be biphasic (as in alternating current) rather than monophasic (as in direct current). In other words, current should flow one way and then the other way between the needles, rather than always the same way:
Frequency
Frequency (more accurately, the pulse repetition rate or number of pulses delivered per second) is measured in units of Hertz (Hz). In EA, a 'low frequency' (LF) would be approximately 2-4 Hz or pulses per second. A 'high frequency' (HF) would be 50-200 Hz.
Amplitude/intensity
Depending on the type of equipment used, amplitude may be a measure of current or voltage. In EA, maximum amplitude may be of the order of 12 mA (milliamperes), or 9 V (volts), but these figures will vary considerably depending on equipment design, and will take account of safety issues for the particular device in question. The strength of sensation experienced by the patient depends on amplitude more than on frequency. Sometimes the level of stimulation is described as 'sensory' (feelable), 'motor' (resulting in muscle twitching) or 'noxious' (frankly painful).
Mode
Stimulation may be continuous (CW) (as in Fig. 1a above), intermittent (burst), 'dense-disperse' (DD, alternating higher and lower frequencies), or otherwise modulated:
Waveform
We usually think of waves as curving, rolling, moving forms in nature. In EA, however, square (or rectangular) waves are mostly used, as illustrated here, although some EA devices produce spike or other waveforms.
Stimulation ranges
It is helpful to consider two main types of stimulation: low frequency (LF)/high intensity (subjectively strong, though still tolerable), and high frequency (HF)/low intensity (subjectively gentle and comfortable). Because of the way these were developed and researched--the former predominantly as EA in China and the latter predominantly as TENS (transcutaneous electrical nerve stimulation) in the West, I have called them 'acupuncture-like stimulation' (ALS) and 'TENS-like stimulation' (TLS), whether they are applied through needles or surface electrodes.
At around 15 Hz, a frequency between the LF and HF ranges, effects may depend on both mechanisms. There is still lack of agreement on whether frequency or intensity is more important in terms of outcome.
EA is frequently used in the treatment of peripheral facial paralysis. The discussion that follows illustrates some of the basic principles involved.
Cautionary note
Electroacupuncture, like any form of electrotherapy, should only be practised following proper instruction and with knowledge of its safety aspects.
Peripheral facial paralysis (PFP) (Bell's palsy, idiopathic facial paralysis)
Aetiology and incidence
Facial paralysis is the result of a motor neuron lesion. This may be peripheral (lower, below the nucleus of the nerve cell, or 'infranuclear') or central (upper, 'supranuclear').
Most cases (around 60-75% (7)) of peripheral facial paralysis (PFP) result from virally induced inflammation of the peripheral facial nerve (cranial nerve VII), (8) or its compression due to vasospasm or oedema, generally in the mastoid region. Occasionally the condition is bilateral. (9) It is particularly associated with herpes simplex or zoster infection, and may be precipitated by exposure to draughts on the face. (10) An unpleasant variant is Ramsay Hunt's syndrome (herpes zoster oticus), in which paralysis is associated with a herpetic rash in or around the ear or on the roof the mouth. (11) This condition also involves the acoustic nerve (cranial nerve VIII), which emerges from the brain just behind the facial nerve. (12)
The facial nerve may also be damaged by surgery for removal of an acoustic neuroma, or by trauma. In one standard physical therapy textbook, surgical damage was estimated to be responsible for 13% of cases of PFP, and other trauma for about 6%. (13)
As with any nerve injury, compression to the facial nerve results in neurapraxia (often spelled neuropraxia), a localised conduction block that recovers relatively quickly (within days or weeks) or, if more severe, in axonotmesis, degeneration of the nerve beyond the injury, with subsequent slow regrowth of the nerve (at an average of some 1 mm daily). Complete severance of the nerve, neurotmesis, may mean that it is highly unlikely to grow back to its target tissue.
PFP or Bell's palsy is not uncommon, with a reported incidence of 13-34 per 100,000 according to different epidemiological surveys, (14) occurring most frequently between the ages of 20 and 40 (15) (although I had it myself as a teenager, after sitting in a draught after suffering chicken pox).
In some instances, the supranuclear pathway is involved as a result of cerebrovascular accident, with cortical or corticobulbar lesions, dissociation of voluntary and involuntary facial movements, and possibly other ipsilateral paralysis or aphasia. This can be differentiated from PFP by assessing the effects of magnetic stimulation of the cortex and facial nerve on the electromyogram (EMG) of the mentalis (chin) muscle. (16) However, the possibility of simultaneous PFP and asymptomatic cerebral infarction should not be overlooked. (17) Furthermore, as with sensory disorders and the development of chronic pain, when motor conditions become chronic the distinction between peripheral and central may be less clear as cortical reorganisation occurs. (18) Treatment may need to take this into account, working with neuroplasticity within the central nervous system as well as being directed at peripheral regeneration and repair.
Apart from stroke, Lyme disease, brain tumour and other possible causes such as multiple sclerosis and Guillain-Barre syndrome should be ruled out before treating as PSP. (19,20,21)
Pathology and prognosis
Pain behind or in front of the ear may precede the paralysis, which affects the muscles of expression (mimesis), such as those above the eyes (frontalis and orbicularis oculi superioris). Clinical symptoms are likely to include incomplete closure of the eye, drooping of the mouth, and an inability to frown, raise the eyebrow, close the eye, blow out the cheek, show the teeth or whistle. (22) Disordered lacrimation and salivation (too much or too little (21)) occur not only because of loss of muscle control, but also because fibres from the facial nerve innervate both the lacrimal gland and the parotid gland and plexus (parotidectomy may in fact induce temporary facial paresis, (23) or even, unfortunately, permanent paralysis (21)). Further symptoms may include continued pain or numbness, (19) loss of taste in the anterior two-thirds of the tongue due to lesion of the (sensory) geniculate ganglion of the facial nerve, and hyperacusis due to paralysis of the stapedius muscle (innervated by the stapedial branch of the nerve). (24) Muscle twitching may also occur, (19) and one unfortunate sequela can be synkinesis, abnormal involuntary muscle movement accompanying voluntary movements of other facial muscles ('jaw winking', or twitching of the eyelid with voluntary movement of the lips, for example (25)). These sometimes develop as recovery progresses. (26) Contractures were reported in one early electrotherapy RCT to occur in 23% of those with initial complete muscle denervation. (27) (Early fibrillation is not, unfortunately, a sign that muscle is recovering. (28))
Chinese acupuncture studies usually describe three (or sometimes four) stages of PFP:
1. Acute phase (up to 7 days), during which symptoms usually worsen.
2. Stable (or 'resting') period (8-14 days).
3. 'Convalescence' (from 15 days), during which there is usually a gradual improvement in symptoms. (22)
4. Chronic phase (from 2 months onwards). (29)
Without treatment, some 85% of PSP patients show initial signs of recovery within 3 weeks, a further 15% within 3-5 months. Around 66% are fully recovered by 3 months. (30) Thus in one study of 54 patients, voluntary movement appeared 16 days post onset on average, with full recovery by 6.3 weeks. (31)
Overall, a fortunate 80%-84% (32) recover to an acceptable level within weeks to months, although 20-30%, (14) or even one-third (30) of patients may be left with some residual symptoms. More optimistic figures have been given by one Chinese author (19) (75% complete recovery, mostly within 2-3 weeks, 15% with persistent facial asymmetry, and only 5-10% showing poor recovery at 4 months).
For those who suffer Ramsay Hunt's syndrome, there is a less than 20% chance of spontaneous recovery. (11)
Prognosis is better for those with milder symptoms at onset, and who start to recover more quickly, indicating the presence of a neurapraxia and only partial denervation of muscle. (33) A less favourable outcome is likely in those with complete facial weakness (suggesting axonotmesis or even neurotmesis and total muscle denervation), pain other than in or around the ear, and systemic hypertension, (34) as well as in those aged over 50 (15) or 60 (35) at onset.
Conventional treatment and electrotherapy
Conventional treatment of PFP tends to be based on antiviral medication (Acyclovir, Valtrex (36)) and a steroid such as Prednisolone in the acute phase, (8,37,38,39,40) with surgical decompression reserved for serious cases (compound muscle action potential amplitude decrease greater than 90% within 2-3 weeks after onset). (41) It may also include EMG biofeedback, (14) and neuromuscular retraining to inhibit the development of synkinesis. (26)
Electrotherapy originally developed in the West following the discovery in the ancient world that discharges from electric fish, particularly the mediterrranean torpedo and Nile catfish (malopterus electricus), could be used therapeutically (although not to my knowledge for PFP). It is intriguing that Li Shizhen mentions the use of a different catfish (parasilurus asota) as a treatment for facial paralysis in his Bencao Gangmu, (42) but this particular species (like other known species of fish in Chinese waters) does not have the shocking potential of its distant cousins in the Nile. (43) Electrotherapy in China is a Western import.
Electrotherapy has been used for various forms of paralysis since the mid-eighteenth century, usually with the notion that eliciting muscle twitches will somehow encourage recovery. Where applied electrical stimulation results in maximum contraction is termed the muscle's motor point. However, whereas in neurapraxia (partial denervation) it is still possible to excite facial muscle via the motor nerve, in neurotmesis (complete denervation) muscle no longer has any motor point/s and muscle fibre has to be stimulated directly. Without electrical and neurochemical input, muscle soon atrophies, with increasing degeneration and fibrosis, a process beginning within 1 to 2 weeks after the initial lesion and complete (and very possibly irreversible) by about 3 years. (44) Facial muscle, however, tends to atrophy somewhat more slowly than other larger muscles, (14) and perhaps for this reason electrical stimulation can have a greater effect on the small muscles involved in PFP than on larger muscles elsewhere in the body. (32)
There is much controversy over the usefulness of stimulating denervated muscle. With reduced circulation, self-repair becomes more difficult in the event of trauma, so excessive exercise (electrically induced or otherwise) is best avoided as it may increase fibrosis. It may also delay reconnection of nerve and muscle, (28) and activate neurochemical feedback that in fact slows nerve regrowth. (45) Thus poorly selected electrical parameters may even inhibit neural regeneration after peripheral nerve injury. (46,47) However, stimulation can benefit the muscle by maintaining nourishment to the tissue and aiding repair, so delaying atrophy and fibrosis even if not completely preventing them. (44,48) It also fosters a return to normal voluntary use once reinnervation occurs. (49)
One form of muscle stimulation called trophic electrical stimulation (TES) uses low frequencies and amplitudes based on the 'patterned' firing characteristics of motor units themselves, rather than the 'more is better' tradition of most methods that use constant frequencies. (50) It is therefore less fatiguing, (51) and appears to maintain muscle tone by altering metabolism rather than by providing a form of 'induced exercise'. (14,52) For PFP, TES uses a range of frequencies between 5 Hz and 15 Hz. (53) Interestingly, frequencies in the physiological tremor range (~10 Hz) may be more effective than twitch (slower) or tetanic (faster) frequencies in stimulating circulation (and so enhancing tissue repair). (54,55,56,57)
Sustained contraction of muscle (tetany) occurs if completely denervated muscle is stimulated at around 3-10 Hz (a much lower frequency than in normal muscle). (58) It would thus seem logical to use low-intensity LF (59,60) stimulation with short pulse durations, rather as in TES, in preference to the strong and long higher-frequency tetanic pulses often advocated in the past. (61) Long interruptions (of 30 seconds, (62) 4 minutes, (63) even 15 minutes (64)) between contractions have also been advocated, with short treatments repeated at least twice or even three times (65) daily to reduce muscle fatigue, (63) although muscle fatigue as such may have little effect either way on the rate of reinnervation. (66) Despite these various suggestions, there are no generally accepted guidelines on optimum parameters.
If reinnervation is possible, except in simple neurapraxia it is in a race against muscle degeneration. Clearly then it is important to begin stimulation as soon as possible after the lesion, (66,67) while it may appear futile to attempt to work an apparently fibrosed muscle. In between these two extremes, it is a matter of clinical judgement whether to stimulate or not.
Once normal innervation is re-established, there is little to be gained by continuing stimulation. (49)
Electrotherapy for PFP: the evidence
Experimentally, electrical stimulation has been shown to benefit axon regeneration in rabbits with traumatic facial nerve injury. (68) Despite such evidence, and despite considerable theoretical support for the application of electrical methods in the treatment of PFP, there are surprisingly few clinical studies that unequivocally support the use of electrotherapy for this condition. (14,52) In their 2003 review, Rosie Quinn and Fiona Cramp found for example that 'conclusive findings relating to the efficacy of electrotherapy in Bell's palsy are still lacking' (as so often, because of methodological shortcomings in clinical studies). However, they also suggested that 'there is no evidence to suggest that electrical stimulation is beneficial to patients with acute Bell's palsy, but evidence does exist to suggest beneficial effects of electrical stimulation in patients with chronic Bell's palsy'. Another 'best evidence' review again found no evidence (published in English) that electrotherapy is beneficial in acute PFP, although stating that its use might be justifiable in long term Bell's palsy. (69) When it comes to other electrotherapy modalities, Quinn and Cramp concluded that ultrasound may benefit acute Bell's palsy, but that there is no convincing evidence that shortwave diathermy and low intensity laser therapy (LILT) are useful for the condition. (14)
Given the paucity of good quality research, it is hardly surprising that an official US report from 1984 found that 'electrotherapy ... has no demonstrable beneficial effect in enhancing the functional or cosmetic outcomes in patients with Bell's palsy', (70) or that in 1989, a standard physical therapy textbook still concluded that 'electrotherapy may not be clinically effective' for this condition. (13) Some authors even state categorically that electrical stimulation should not be used for facial paralysis. (71) Others suggest that any electrical stimulation is contraindicated if its purpose is to stimulate flaccid muscles, as this may foster the development of synkinesis, where the aim should be to inhibit contracture rather than to encourage it. (26) Thus Medicare in the USA does not cover electrotherapy for the treatment of PFP, (72) while some insurance companies consider electrical stimulation only as 'investigational/ not medically necessary'. (7)
It is interesting that the one study that meets with the approval of all the reviewers is one on TES. (73)
Acupuncture
Acupuncture has frequently been used for Bell's palsy. One Chinese review of the acupuncture literature on PFP over 50 years cites over a thousand articles, of which just over 15% were randomised controlled trials (RCTs) or controlled trials (CTs). (74) Traditionally, acupuncture is considered very effective for the condition. Thus another Chinese non-systematic review of 50 studies carried out over a 10-year period found a complete recovery rate averaging some 81% (37%-100%). (75) There are other claims of 95%76 or even 99.6%. (77)
Given the ~80% spontaneous recovery rate, it is perhaps not surprising that there are many reports of MA being helpful for facial paralysis. (78,79,80,81,82) MA has also been employed for facial paralysis due to diabetic (motor) neuropathy, particularly of the oculomotor nerve, (80,83) and is sometimes combined with other traditional interventions such as bleeding (84) or cupping. (85) Reviews of the many acupuncture-based methods used have been published, (75,29,86) as well as a 2003 Cochrane systematic review on the subject. This authoritative if poorly reported and very limited source, based on a total of only 288 patients in three RCTs in which acupuncture (or acupuncture plus medication) was reported as superior to medication alone, found that there is still 'insufficient evidence from randomised trials to decide whether acupuncture is helpful' for Bell's palsy. (15) It is important to note that this review was limited to cases treated within 14 days from onset and excluded chronic sequelae and cases involving diabetes, herpes zoster or other causes. Also excluded were TEAS, pTENS and LA.
In general, clinicians and less systematic reviewers have concluded, like Zhang Hong in this journal, (22) that acupuncture, whether MA or EA, can shorten time to recovery and enhance curative effect. (87,88,89,90)
Predictably, less good results are reported for Ramsay Hunt's syndrome, (91) while in one large Russian review facial paralysis of vascular origin had the least good prognosis of all the types treated. (35) (However, any intervention that improves local circulation is likely not only to help release local nerve compression but also to assist nerve regeneration. (92) MA, for instance, has been found to increase facial temperature in patients with Bell's palsy, (93,94) with temperature also increasing in response to auricular MA in one successful case. (95))
Traditional Chinese medicine (TCM) and PFP
In TCM terms, PFP is usually considered to result from the invasion of wind-cold due to an underlying deficiency of qi or poor circulation in the channels and collaterals in the face, with resultant stagnation of qi and blood. The condition may also be complicated by pre-existing phlegm. (19) Disharmony of Liver qi has also been proposed as a contributory factor. (96) Acupoints may be selected according to a further differentiation (channel blockage due to wind-cold or wind-heat, qi and blood stagnation, or qi and blood deficiency). (29) Once PFP has become chronic, Liver and Kidney yin deficiency may complicate the picture. (29) One author has suggested that PFP caused by invasion of wind-cold is most responsive to acupuncture treatment. (97) It is instructive that Julius Althaus, one of the greatest European electrotherapists of the nineteenth century, attributed most cases of Bell's palsy to the influence of damp and cold. (98)
Bleeding (at jing-well points), (99) and bleeding and cupping, (100) have been used in the acute phase of PFP, as well as bleeding alone for chronic PFP with blood stagnation. (101)
In keeping with conventional electrotherapy findings, better results have been reported with MA when higher electrical potentials are found at acupoints on the affected side than at symmetrical points on the opposite side, particularly if these potentials increase markedly with the first treatment. (102) One group of researchers has also used temperature differentials between the affected and unaffected side to determine MA point selection. (103)
Electroacupuncture in the treatment of peripheral facial paralysis
Because of its effects on pain, paralysis, muscle wasting, microcirculation, inflammation and nerve damage, we would expect EA to be perfectly suited to the treatment of PFP (although Bruce Pomeranz has suggested that simple manual needling may in fact induce electrical 'current of injury' levels and densities in precisely the range required for nerve regrowth (104)).
Indeed, in experimental studies EA has been found to benefit facial nerve regeneration following trauma, (105,106) while a quick Medline search (February 2007) using the terms 'facial paralysis' AND 'electr*' reveals more studies on EA than on all other forms of electrotherapy for PFP, at least in recent years.
Furthermore, in the present journal (Journal of Chinese Medicine, 1979-2006 (107)), 8 of 16 articles, case studies or abstracts on PFP included discussion of EA. And in one 2005 comprehensive review of the Korean acupuncture literature (1983-2001), (108) of 124 studies retrieved, 9 were on PFP, and of these only one did not make use of electrical stimulation.
The clinical studies database at www.elecroacupunctureknowledge.com currently includes 167 studies on PFP, including full details of acupoints and electrical parameters used in each study (if known). Please note that this database does not include or exclude studies on the basis of methodological merit. While it provides an essential contribution for the formulation of further treatment and research protocols, authors' claims as to outcome may not be sustainable when subjected to rigorous scientific criteria.
Analysis of the clinical studies database indicates that many authors have observed that EA gives better results than MA for PFP (75) (see too below, under Comparisons and Combinations). Some have gone so far as to suggest that acupoint electrostimulation (without needles) is 'a method of choice' for Bell's palsy, (109) although others, more cautious, have stated categorically that electrical stimulation should not be used for facial paralysis. (78)
Treatment according to stage and severity of paralysis
The three standard stages of PFP described in the Chinese literature have been mentioned above. Selecting appropriate acupuncture treatment at each stage may speed up recovery110 and improve results. (111,112)
1. Acute phase
Symptoms normally worsen during the 7 days or so of this phase and then level off. Thus early aggravation may be erroneously attributed to acupuncture (although it may also result from incorrect treatment). (22) On the other hand, stability of symptoms in one case study when treatment was started only towards the end of the acute phase was attributed to EA! (19)
Except in cases of simple neurapraxia it is usually considered important to begin stimulation as soon as possible after the lesion occurs, even though the effects of acupuncture may not be evident until the acute phase is over (113) (except perhaps to the electrophysiologist (114)). Thus in acupuncture generally, the emphasis is very much on early treatment. (97,115,116,117,118,119,120,121,122) In one small study (N = 22) of EA initiated between 1 and 30 days after onset of PFP, for example, results were better in those treated earlier. (123) Similarly with LILT, with better results in those treated less than 15 days after onset reported in another small study (N = 17). (9) Despite such plausible evidence, Zheng Qiwei and Li Zhenbo have cautioned that EA should not be used initially, for fear of inducing spasm. (124,19) Authors such as Cui Shugai, (125) Qiu Meihua (126) and Wu Yixin et al (120) have followed this approach.
One approach to initiating treatment during the acute phase is to use points on the healthy side of the face, and points on the affected side only in the stable period. In one MA study this gave better results than routine acupuncture and moxibustion in all three phases. (127) In another, results with contralateral MA were better than with TDP to the affected side along with intravenous medication. (128) Surprisingly, there appear to be very few studies in which EA was applied on the nonparalysed side, (129) although there are some in which it was used bilaterally on facial points. (130,131,132)
Superficial needling has been used in several acupuncture studies, (133) in at least one explicitly during the acute phase and early stable period (with better results for MA than standard Western medicine, WM). (134) In another such study, although overall results were similar for both superficial needling and conventional acupuncture (MA), sequelae were less with the former, (135) and in one RCT superficial needling was better than point-to-point needling (disease stage unclear from the study abstract). (136) Superficial needling has also been used for chronic PFP. (85)
Gentle needling was found superior to strong stimulation in one MA report on early stage PFP (137) (and to improve and speed up results with standard WM in another). (87) However, this may not be a universal finding: strong stimulation (with point-to-point needling) in a study of acute stage and early stable period PFP resulted in a 100% total effective rate (herbal medication and a steroid only providing 55%). (138)
Although in one large RCT on acute PFP (N = 477), superficial MA was found superior to 1 Hz EA, (139) EA with carefully controlled parameters (140,141,142,123) (as well as other forms of acupoint electrostimulation (143)) has been found helpful during the acute phase. Thus, in another controlled trial (N = 80) where gentle (just perceptible) EA was started within 14 days of onset, results were considerably better than when treatment was begun later. (22) Such studies appear to contradict the cautions of Zheng Qiwei and Li Zhenbo against using EA at all during the initial acute phase (of course relatively gentle EA is by no means contraindicated later on (144)).
Nonetheless it should not be forgotten that strong local electrical stimulation of the affected side may well be counterproductive. (145,19) Such stimulation of denervated muscle may potentially lead to contractures and synkinesis, (146) especially early on. (124) However, one much cited electrotherapy RCT from 1958 found that interrrupted galvanic stimulation (pTENS) sufficient to elicit only 'minimal' contractions did not adversely affect the development of facial muscle contracture despite being used in the acute phase of PSP. (27) Provided treatment is carefully designed and carried out, electrical stimulation is not contraindicated during the acute phase of PFP.
There is also some justification for using both ultrasound (14) and (possibly) microwave diathermy (147) or TDP (148) during the acute phase.
2. Stable period
Most MA and EA studies consider the acute phase and stable period together, dividing treatment into that started in the first two weeks after onset and treatment begun later.
3. Convalescence (and chronic phase)
Prolonged sequelae of PFP (more likely in older patients) tend to be refractory to both MA and EA. Thus, as already stated, most sources emphasise the importance of starting treatment early. In a comparison of two EA case histories by Li Zhenbo, for example, PFP first treated at two months responded more slowly and less well than acute Bell's palsy treated only five days after onset. (19) In contrast, one standard NMES (neuromuscular electrical stimulation) protocol, perhaps erring on the side of caution, advocates delaying treatment until two months after onset. (149)
In line with standard acupuncture practice, treatment may usefully be continued for some weeks after apparent clinical recovery, depending on EMG findings, (150) although not all agree that this is essential once normal innervation is re-established.
In contrast to acute phase PSP, strong stimulation may now be appropriate. (121) This was found superior to uniform reinforcing-reducing in one comparative trial of MA, for example. (151,152) Similarly, in a number of EA studies in the clinical studies database treatment is started gently, gradually increasing intensity (and sometimes frequency) as the condition becomes more chronic.
Severity of the condition
The severity of a nerve injury will determine how rapidly recovery will take place, and what effect EA will have on this. Treatment will give poorer results in those with more severe pathology. (153)
The presence of incomplete paralysis in the first week is a favourable prognostic sign. (154) The response of affected muscles to an initial session of intermittent EA has itself been used to assess prognosis (155) (more accurate prognosis may be obtained through electrical measurement (31,156,157,158,159,102) or other methods (160)). In simple neurapraxia, EA may not even be needed.
If recovery is delayed, then more than a simple neurapraxia may be involved, with axonotmesis or degeneration of the nerve peripheral to the lesion (as often occurs following neuroma surgery). In these cases, recovery is likely to be incomplete. As degeneration can set in within a few days, many physical therapists consider early treatment to be important, directed at first to relieving pressure on the nerve in the case of neurapraxia. (161) However, even treatment several years after the initial insult can produce useful results in cases of axonotmesis if patients (and practitioners) are willing to persist with it. (146) At this stage, the aim of treatment is to assist nerve repair and facilitate muscle reeducation.
Lesion location
Several studies indicate that the lower (more peripheral) the lesion along the facial nerve, the better the therapeutic effect of acupuncture (162,163,24) and moxibustion. (164) The authors of one RCT found that whereas cases with lesions outside the facial (nerve) canal tend to recover spontaneously, lesions within the canal benefit from acupuncture. (165)
Comparisons and combinations
Comparisons
EA is more effective than MA according to a number of studies, (166,167,168,117,169) with fewer treatments required. (117,170) However, in a large RCT (N = 477) on acute PFP, MA (with multiple superficial needling) was superior to 1 Hz EA. (139) On the other hand, LF EA gave better results than vitamin B12 acupoint injection plus medication in another report (171) (in another RCT, point injection was found better than routine MA (172)).
pTENS ('galvano-acupuncture') was found to be more effective than 'ordinary acupuncture' in one RCT. (173)
TEAS was more effective than MA in one study, with fewer treatments required. (174) In another, the effects of EA and TEAS were similar, (175) whereas in a third the combination of TEAS and TDP with MA improved the results compared with those from MA alone. (176)
LA and MA were equally effective in some studies, (177,178) although LA was less useful than MA (or MA plus moxibustion) in one large RCT. (179) However, the addition of Helium-Neon LA to LF EA improved rate of cure (but not overall effective rate) in one 2003 CT. (180)
TDP (plus medication) gave similar results to MA in one CT, but took longer to achieve them. (128)
Combinations
Somewhat surprisingly, EA appears from the clinical studies database to be combined most commonly with acupoint injection for PFP.
EA has frequently been combined with TDP (possibly even more than with moxibustion), and in recent years with microwave diathermy (giving better results than diathermy alone in one report on acute stage PFP (142)). Given the TCM aetiology of the condition, it is quite surprising that there are not more studies combining MA and moxibustion.
Moxibustion in combination with EA has been used in the treatment of facial paralysis, (181) with heat considered particularly appropriate in chronic cases by some authors. (182,183) A common sunlamp has also been used, (86) as has far infrared. (184 185) Both moxibustion (in one study at Yangbai GB-14, Xiaguan ST-7 and Qianzheng N-HN-20, (183) in another at Yifeng SJ-17 (186)) and far infrared (TDP) (148) appear to improve the results of EA, as well as MA. (176,184) The combination of far infrared with MA has also been claimed to reduce the amount of treatment needed. (185) In keeping with reports that EA often gives better results than MA, the combination of EA with moxibustion was found superior to MA in one RCT. (168)
Further analysis of comparisons and combinations may be found in my textbook. (1)
The role of exercise
LF EA has been combined with functional exercises. (170) In studies comparing acupuncture plus facial exercises with acupuncture alone, results were significantly better in the former group. (187,188) Adjunctive exercises (whether volitional or induced) have an important role to play in PFP, (52) particularly once recovery begins, (115) although exercises have also been effectively combined with LF EA in acute phase PFP. (189) However, too much emphasis on mirror work (making faces) can be disheartening if progress is slow. (190) Exercise has to be tailored to recovery stage. (26)
Points used
A TCM approach
Traditionally, points are selected according to pattern of differentiation. Ren Xiaoqun, for example, suggests the following points:
* For channel blockage due to wind-cold: Fengchi GB-20, Hegu L.I.-4 (with moxibustion).
* For channel blockage due to wind-heat: Yifeng SJ-17, Yanglingquan GB-34.
* For qi and blood stagnation: Waiguan SJ-5, Sanyangluo SJ-8, Taichong LIV-3
* For qi and blood deficiency: Zusanli ST-36, Sanyinjiao SP-6. (29)
Anatomical acupuncture
Others have preferred a Westernised approach (see Table 3 on the website version of this article), one group suggesting that selecting points according to the distribution of the main branches of the facial nerve can be effective even with gentle or superficial MA, (133) another author using such points for stronger MA with point-to-point needling in cases of more chronic PFP (ST-6 to ST-4; an empirical point midway between Yangbai GB-14 and Sizhukong SJ-23 to Xiaguan ST-7; Yifeng SJ-17). (152) A rational selection of points might include Zanzhu BL-2, Sizhukong SJ-23, Yangbai GB-14 and Taiyang M-HN-9 for involvement of the first (temporal) branch of the facial nerve, Quanliao SI-18 and Chengqi ST-1 for second (zygomatic) branch involvement and Dicang ST-4 with Jiache ST-6 for the third (mandibular) branch. (182) (See too Table 3). An important point is Yifeng SJ-17, located where the facial nerve emerges from within the skull. (191)
Incidentally, there are very few PFP studies comparing the effects of stimulation at acupoints and non-acupoints. In one, EA at points over the nerve trunk had a better effect than similar EA at standard acupoints, (192) while in another EA at Hegu L.I.-4 and the auricular Mouth point gave superior results to MA at nonspecific points (193) (hardly a fair comparison). Non-acupoints over the trajectory of the facial nerve were stimulated in one very small uncontrolled LILT study (N = 4). (194)
An alternative approach is based more on the muscles involved rather than the nerves (see Table 3). Thus Zanzhu BL-2 and Yangbai GB-14 have been recommended for difficulty in frowning, Sizhukong SJ-23 and Yangbai GB-14 for difficulty in raising the eyebrow, Juliao ST-3 and Dicang ST-4 for an inability to smile, and Yifeng SJ-17, Dicang ST-4 and Jiache ST-6 as general points. (195) Point-to-point needling from Zanzhu BL-2 to Yuyao M-HN-6, with Yangbai GB-14, is another method taught for incomplete eye closure in China. (196) Other points for EA have been suggested by Zheng Qiwei: Taiyang M-HN-9 and Zanzhu BL-2 or Sibai ST-2 for incomplete eye closure; Yingxiang L.I.-20 and Quanliao SI-18 or Xiaguan ST-7 for difficulty sniffing; either Dicang ST-4 and Jiache ST-6 or Xiaguan ST-7 and Dicang ST-4 for difficulty in puf.ng out the cheeks; and Kouheliao L.I.-19 and Dicang ST-4 for deviation of the philtrum. (124) Wong has given a useful account of some nontraditional muscle levator points. (191)
Staging treatment
Ren Xiaoqun suggests that during the acute (and resting) stage, only distal and proximal but not facial points should be utilised (Yifeng SJ-17, Wangu GB-12, Fengchi GB-20, Taichong LIV-3, Hegu L.I.-4, for example). If facial points are used at all, only a few should be stimulated (Xiaguan ST-7 to Taiyang M-HN-9, Jiache ST-6 to Dicang ST-4, for instance). (29) Zheng Qiwei also recommends that not many points should be stimulated initially, maybe two to four from the affected area. (124) Chen Kezhen, another experienced reviewer, suggests Dicang ST-4 and Xiaguan ST-7, with Yingxiang L.I.-20 and Taiyang M-HN-9 on the affected side, together with Hegu L.I.-4 on the opposite side. (86)
Rather than connecting points on the face, Li Zhenbo in one case report paired Hegu L.I.-4 with Dicang ST-4 and Hegu L.I.-4 with Jiache ST-6, alternately. (19) Simple combinations of Yangbai GB-14-Hegu L.I.-4, Sibai ST-2-Xiaguan ST-7 or Dicang ST-4-Hegu L.I.-4 have been recommended for use with single-output stimulators. (197)
The use of distal points
Although Wong is rather disparaging about the use of distal points, (191) the authors of one MA study consider that stimulating distally does add to the effect of purely local treatment. (198) When using EA, one advantage of stimulating points away from the affected area is of course that there is no risk of inducing contracture or synkinesis in the early stages of PFP. Thus Zheng Qiwei quite happily recommends the early use of EA at Hegu L.I.-4 and Waiguan SJ-5 (with bilateral Hegu L.I.-4 points connected to one output of the EA device and the Waiguan SJ-5 points to a separate output). (124) In the clinical studies database there are many reports in which distal points on the limbs are used bilaterally in this way, and probably almost as many in which Hegu L.I.-4 is used, but only on the healthy side (although in one MA study, bilateral stimulation of hand points was found to be more effective than unilateral treatment (97)).
Mining the clinical studies database
Looking through the numerous studies in the database, it is clear that predominantly local points are used, selected to activate particular paralysed muscles, together with some distal points. The most commonly used points appear to be Yangbai GB-14, Dicang ST-4, Jiache ST-6 and Xiaguan ST-7, with Hegu L.I.-4 (indicated > 70 times in the database ), followed by Yifeng SJ-17, Yingxiang L.I.-20, Sibai ST-2 and Taiyang M-HN-9 (> 50 times), Zanzhu BL-2 and Fengchi GB-20 (> 40 times), Sizhukong SJ-23, Quanliao SI-18, Chengqiang REN-24, Renzhong DU-26 and Yuyao M-HN-6, with Zusanli ST-36 (> 20 times). Mentions of the stellate ganglion (199) and the crossing point of the Large Intestine and Gall Bladder channels above the clavicle (200) are intriguing.
It should not be forgotten that stimulation of totally denervated muscle (without sensation as well as movement) is unlikely to give good results.
Parameters used
Intensity and pulse duration
Chen Kezheng has suggested that low-intensity EA should be used, just strong enough to elicit muscle contraction. (86) Alexander Meng and Gertrude Kubiena also suggest gentle motor level stimulation locally (10-15 minutes of DD or intermittent), stronger stimulation being appropriate at distal points, (182) with the option of gentle and brief TEAS, daily initially for 4-5 days, then twice weekly, and so on. Only 5-10 minutes of mild motor level LF EA (every other day) is recommended in one Hong Kong text. (5) However, in the clinical studies database, while motor level stimulation ('to induce slight contraction of facial muscle') is emphasised, 'gentle' stimulation or stimulation 'to patient's comfort' occurs far less frequently than the standard Chinese 'intensity to tolerance' (or even 'maximum tolerance').
To obtain movement in muscle that is completely paralysed, longer pulse durations will be required (201) (even as long as 1-100 msec (146)).
Frequency and mode
From the clinical studies database, the most frequently used frequencies and modes for EA treatment are LF, intermittent or DD stimulation, although 20 Hz, 50 Hz, 80 Hz and even 125 Hz are also mentioned. The Acupad NT 10, a TENS-like device found useful in home treatment of PFP, provides an output at a fixed 22 Hz. (1)
In one interesting RCT (N = 147), a combination of continuous (CW) followed by DD stimulation gave better results than CW alone. (202) In another RCT (N = 80), intermittent stimulation gave better and more rapid results than LF CW (TDP was used in both groups). (203) This appears to be in line with standard electrotherapy practice involving interrrupted HF stimulation to patient tolerance, eliciting visible muscle contractions if possible. (149)
On the other hand, the authors of one case study suggested that for elderly or debilitated patients, weaker (HF) EA is more appropriate than strong (LF) EA. (204)
Another approach (extrapolating from MA studies) could be LF stimulation of scalp points at around 3.3 Hz. (79) Users of the Likon device were at one time taught to utilise frequencies in the 5-10 Hz range, modulated at 0.25-0.33 Hz, for PFP. (197)
Treatment frequency
One RCT comparing daily and twice-weekly EA for PFP found no significant difference in therapeutic effect when treatment was initiated within three months of onset. (205)
Other approaches
As a form of supervised self-treatment, low-intensity trophic electrical stimulation (TES) using low variable frequencies as found in normal motor unit action potentials (MUAPs) may be beneficial: 5-8 Hz, 80 [micro]s, alternating two seconds on and off, for up to eight hours daily, (44) or with submotor stimulation as described in a study by Robert Targan and colleagues. (146) A useful patient handbook on facial paralysis by one of the originators of TES is now available. (206)
In a wonderfully simple protocol by He Qinglin, suited to an unsophisticated rural practice, Dicang ST-4 and Jiache ST-6 are stimulated using from one to four ordinary 1.5 V batteries ('economic, convenient and effective'). (207) If such non-charge-balanced stimulation really has to be used (which with needles it should not), it may be helpful to position needles or electrodes so that the more distal one is negative. (1)
Staging treatment
Many authors emphasise gentle stimulation (with more superficial needling) during the acute phase, as mentioned above. During the convalescent stage, stronger EA becomes appropriate, with point-to-point needling (29) to maximise stimulation of the facial muscles themselves (rather than just the nerve fibres that feed them).
After limiting treatment to mild stimulation in the first week (acute phase), it can then be made a little stronger. This strategy is frequently found in the clinical studies database. Interestingly, the authors of one report on TEAS for various stages of PFP gradually increased both frequency and amplitude to their patients' tolerance. (173)
Bearing in mind MA studies by Yu (208) and Ni (209) on the relation between duration of needle retention and therapeutic effect, it would seem sensible to start with shorter treatments and only lengthen them after the acute (or even 'resting') phase. This approach was adopted in EA studies by Wang, (210) Liu and Li, (211) Tang and Fang, (140, 141) and Yang et al, (212) for example. Electrostimulation for long periods should be avoided in the early stages of PFP or if spasm is already present. (197, 29)
On the other hand, in keeping with traditional guidelines on acupuncture treatment, Li Zhenbo suggests that early on treatment should be given daily, or every other day, but only every few days if the condition is chronic. (19)
Discussion: some thoughts on treatment
In this article, electroacupuncture and electrotherapy are introduced, and their application in the treatment of PFP is outlined. There is a lack of good quality data on treating PFP with electrotherapy, but a surprising amount of information is available on its treatment with EA. Each can learn from the other.
What is clear from reviewing the literature is that many different approaches have been adopted. There is no one right way to treat PFP, although there do seem to be some wrong ways. The following guidelines are suggested:
* Treatment must be adapted to the three (four) stages of PFP, with only gentle stimulation applied in the acute phase and at only a few acupoints.
* In terms of needle technique, this means superficial rather than point-to-point needling.
* For EA, it means using a low frequency at a low intensity (and possibly with a relatively brief pulse duration): sensory (even submotor) level first, motor level later.
* Initially, 15-20 minutes of EA may suffice, later 20-30 minutes.
* If in doubt, use EA during the first week only at distal points, away from the face altogether.
* In general, however, the same points are used with EA as with MA, although it is helpful to select points according to their anatomical (muscle/nerve) location as well as their TCM function.
* The combination of local and distal points is likely to give better results than using just one or the other.
* Despite the frequent use of TLS for acute pain disorders, LF EA should be used initially (although not at high intensity, as in ALS), and possibly even through to stage 3 PFP (with increasing intensity).
* In general, DD is more likely to be effective than CW, but chronic (stage 4) PFP may perhaps respond to HF or intermittent stimulation.
* However, given that the one study that meets with the approval of all the electrotherapy reviewers is one on TES, it would seem sensible to adapt the parameters developed for this method for use with EA, perhaps using variable frequencies in the 5-8 Hz range or at around 10 Hz, rather than the more common 2-4 Hz. Treatment should be designed to foster local circulation and nerve healing, rather than simply provide induced exercise for paralysed muscles.
* Concomitant use of heat and other ancillary treatments may potentiate the effect of EA. Facial exercises are also very important.
* Treatment twice a week may be as effective as daily treatment when using standard EA (but not with protocols based on TES).
Note: This article is abridged due to space constraints. The full article at www.jcm.co.uk/JCM Journal/Latest Issue includes a comprehensive table of facial muscles, nerves and corresponding acupuncture points and full references.
This article on the JCM website
The References to this article can be found on the JCM website at www.jcm.co.uk/JCM Journal/Latest Issue, together with the following Tables:
Table 3. The main muscles affected by peripheral facial paralysis, their innervation and possible motor point/acupoint correspondences
Table 4. Studies on EA and related modalities for PFP
Acknowledgements
To Elsevier (Churchill Livingstone) for permission to adapt and reprint material used in my textbook on electroacupuncture.
To Diana Farragher OBE FCSP and Wendy Walker MCSP of the Lindens Clinic in Sale, Cheshire, for taking the time to read this paper and for their helpful criticism, comments and references (I have found the website www.bellspalsy.com particularly useful).

To Professor Huang Longxiang of the China Academy of Chinese Medical Sciences for his assistance with translation of electrical and other terms in some of the more recent studies used.
To Danny Maxwell for his skilful editorial help.
To Ruben de Semprun at Allerton Press for assistance with references in the International Journal of Clinical Acupuncture.
Abbreviations used
~ Approximately
ALS acupuncture-like stimulation
CT Controlled trial (non-randomised)
CW Continuous stimulation (at constant frequency)
DD Dense-disperse (alternating frequencies)
EA Electroacupuncture
EHF Extremely high frequency
EMG Electromyogram
HF High frequency
LA Laser acupuncture
LF Low frequency
MA Manual or traditional acupuncture
MUAP Motor unit action potential
N Number of patients in a study
NMES Neuromuscular electrical stimulation
PFP Peripheral facial paralysis (Bell's palsy)
pTENS probe or point TENS, using a small diameter handheld probe
RCT Randomised controlled trial
TCM Traditional Chinese medicine
TDP Te ding dian ci bo pu (type of far-infrared lamp)
TEAS Transcutaneous electrical acupoint stimulation
TES Trophic electrical stimulation
TENS Transcutaneous electrical nerve stimulation
TLS TENS-like stimulation
WM Western medicine
Terms that may be unfamiliar to some readers
Axonotmesis = Degeneration of nerve beyond the point of injury
Compound muscle action potential amplitude = A measure of electrical activity in a group of muscles
Contralateral = Pertaining to the opposite side
Cortical = Pertaining to the (cerebral) cortex
Corticobulbar = Pertaining to the cerebral cortex and brainstem
Denervation = Interruption of nerve supply to tissue (may be partial or total)
Hyperaesthesia = Increased, sometimes extreme, sensitivity to stimuli
Hyperacusis = Exceptionally acute hearing, sometimes accompanied by pain
Infranuclear = Below or peripheral to the nucleus of a neuron
Ipsilateral = Situated on the same side
Neurapraxia (neuropraxia) = Conduction block in injured nerve that recovers relatively quickly
Neuropathic pain = Pain that originates from trauma or injury to the nervous system itself
Neurotmesis = Complete severance of a nerve
Ramsay Hunt's syndrome = Facial paralysis associated with a herpetic rash in or around the ear or on the roof the mouth
Segment = Section of the spinal cord, with the skin, muscle, bone and organ regions innervated by the associated spinal nerves
Supranuclear = Above or central to the nucleus of a neuron
Supraspinal = Pertaining to the region above the spine
Synkinesis = Abnormal involuntary muscle movement accompanying voluntary movements of other muscles
Tolerance = Reduced response to treatment following prolonged or repeated us

David F Mayor is the editor of Electroacupuncture: A practical manual and resource (Elsevier/Churchill Livingstone 2007) and the online clinical studies database at www.electroacupunctureknowledge.com.
This searchable database contains more than 8,000 clinical studies on EA and associated modalities, and is available on the CD version of his electroacupuncture textbook as well as freely accessible on the website. Full details of acupoints and electrical parameters used in each study are given where possible.
A traditionally trained acupuncturist in private practice in Welwyn Garden City, David Mayor lectures on electroacupuncture at a number of acupuncture colleges in the UK. He was first exposed to electrotherapy when he contracted Bell's palsy as a teenager. An interest in electroacupuncture developed some fifteen years later, when he translated some of loan Dumitrescu's work on acupuncture from the Romanian. He is a member of the British Acupuncture Council and an honorary member of the UK Acupuncture Association of Chartered Physiotherapists (AACP).
Table 1: Some differences between MA and EA
MA EA
Needle manipulation is Stimulation is continued
brief and intermittent for the duration of treatment
Only 'low frequency' is possible No limitation to frequency of
(twirling or lifting-thrusting) stimulus (frequency-specific effects occur)
Strong manipulation risks tissue Strength of stimulation only
damage limited by patient tolerance

Table 2: Some differences between 'accupuncture-like' and 'TENS-like' stimulation
Acupuncture-like stimulation (ALS) TENS-like stimulation (TLS)
LF (high intensity) HF (low intensity)
2-4 Hz 50-200 Hz
Pulse duration of around Pulse duration of 80-100
200 [micro]sec appropriate [micro]sec optimum
May be used locally or Used locally (for instance
distally (at extrasegmental or at ipsilateral rather than
contralateral acupoints, for contralateral points)
example)
Has segmental and supraspinal Has segmental effects (large
neurophysiological effects diameter fibres inhibit pain signals in small
diameter fibres in the spine)
Releases [beta]-endorphin and Met- Releases dynorphin in the spinal
enkephalin neurotransmitters in cord (and other peptides in the
the brain brain)
Strong stimulation elicits High intensity may be
deqi-like sensation uncomfortable
LF does not produce muscle spasm HF may result in uncomfortable
at high intensity (in normal tetany (but may also be useful
muscle) for spasticity)
Intermittent pulse trains at Intermittent pulse trains at
high intensity may result in low intensity enhance comfort
uncomfortable tetany
Central effects mean analgesia has Spinal mechanism means analgesia
slow onset and lasts longer--30 has rapid onset and does not last
minutes may suffice for ongoing long--longer periods of treatment
effect (cumulative) may be necessary
No 'tolerance' develops from such Tolerance may develop from
short treatments longterm use
Tends to be used more for chronic Tends to be used more for acute
pain pain
For deep, aching, throbbing pain For superficial pain associated
with inflammation
May be helpful for neuralgia May be helpful for neuralgia and
and other neuropathic pain other neuropathic pain (local)
(contralateral or distal)
May benefit peripheral (sensory)
nerve injury
May be used in hyperaesthesia May aggravate hyperaesthesia
(especially if cutaneous)
Used for flaccid paralysis Used for spasticity
(stroke, Bell's palsy)

(Based on Mayor 2007 (1))

Comparison of the effects of electroacupuncture plus cupping with that of the electrical pulse therapy for different types of cervical spondylopathy

By: Huang Liemi

182 cases of cervical spondylopathy were divided into 4 types, and treated with electroacupuncture plus cupping in Group A (90 cases), and with moderate or low electrical pulses in Group B (92 cases). The therapeutic effects on each type of cervical spondylopathy were compared after 3 courses of treatments. The types were as follows: 1. 49 cases of cervical type (CT): local cervical pain and restriction of movement without numbness and pain radiating to the upper limbs. 2. 48 cases of nerve root type (NRT): rigidity in the neck, unilateral or bilateral shoulder pain or with pain radiating to the fingers, cold and weakness of the limbs, and numbness of the fingers. 3. 41 cases of vertebroarterial type (VAT): neck-shoulder pain or neck-occipital pain, and posture-induced vertigo. 4. 44 cases of sympathetic type (ST): occipital pain, dizziness, palpitation, congested sensation in the chest, cold limbs and skin, blurred vision. Of the 90 cases in Group A, 48 were male and 42 female, ranging from 24 to 76 years in age, and from 1 week to 30 years in disease duration. Of the 92 cases in Group B, 45 were male and 47 female; and the age and disease course ranges in this group were comparable to those in group A. Group A received electroacupuncture plus cupping using the following points: bilateral Fengchi GB-20 needled towards the opposite eyeball to a depth of 0.5 cun to cause a needling sensation which radiated to the vertex and temple, Taiyang (M-HN-9), Tianzhu BL-10 Baihui DU-20, Huatuojiaji (M-BW-35) on, above and below the affected cervical vertebra, bilateral Hegu LI-4 and Lieque LU-7. Dazhui DU-14 was needled to a depth of 0.5 cun to cause local soreness and distension sensation radiating to the shoulders. Bilateral Jianjing GB-21 and Jianwaishu SI-14 were added for pain and soreness in the shoulders and back. A G6805-1 electroacupuncture apparatus was used to deliver consecutive pulses, and the bipolar electrodes were connected to bilateral Fengchi GB-20 for cases with dizziness, to bilateral Huatuojiaji (M-BW-35) points for those mainly with pain in the neck and restricted movement, and to bilateral Jianjing GB-21 for those mainly with soreness in the shoulders and back. The treatment lasted for 20 minutes, followed by local cupping for 10 minutes, which was given once daily. The 92 cases in Group B received electrical pulse therapy using electrodes through damp cotton cushions 7cm X 10cm in size placed at the back of the neck and the affected area. A NMT91 multifunctional apparatus was used to deliver a bi-directional 2-4000 Hz electrical pulse for 20 minutes on a daily basis. For both the groups, 10 treatments constituted a therapeutic course, and the therapeutic effects were evaluated after 3 courses of treatment. It was found that the therapeutic effect in Group A in treating the nerve root type (NRT) and the vertebroarterial type (VAT) of cervical spondylopathy was better than that in Group B (P<0.05): Group A's NRT and VAT cases both had 20 effective cases and 2 ineffective each, whereas Group B had 17 effective NRT cases with 9 ineffective, and only 11 effective VAT cases and 8 ineffective VAT cases. The reverse was found in the sympathetic type of cervical spondylopathy. The effect in Group B was better (21 effective, 2 ineffective) than in Group A (13 effective, 8 ineffective) (P<0.05). There was no significant difference in therapeutic effects on the cervical type of spondylopathy between the two therapies (24 out of 25 patients effective in Group A, compared with 22 out of 24 patients in Group B). The authors argue that the appropriate therapies should be adopted for different types of cervical spondylopathy in order to obtain the best result.

Effects of auricular transcutaneous electrical nerve stimulation on distal extremity pain: a pilot study

By: Longobardi, Anthony G.,Clelland, Jo Ann,Knowles, Cheryl J.,Jackson, James R.

Effects of Auricular Transcutaneous Electrical Nerve Stimulation on Distal Extremity Pain: A Pilot Study Pain has plagued the human species for centuries. Approaches to pain management have evolved and changed over the years, but some modern methods correlate with methods used many years ago. Many modern analgesic methods are undesirable or detrimental such as surgery, which is invasive, or use of drugs, which may be addictive. Physical therapists often administer pain-relieving treatments to patients suffering from pain of various etiologies. A noninvasive technique that can relieve distal extremity pain of various etiologies would be a welcome addition to current treatment techniques.

Transcutaneous electrical nerve stimulation is a noninvasive and nonaddictive treatment for pain used by many physical therapists. Recent clinical studies have reported significant decreases in pain following the application of high intensity, low frequency TENS [1,2] and electroacupuncture. [3-5] High intensity, low frequency TENS applied over acupuncture points is referred to as "acupuncture-like" TENS. Acupuncture points on the auricle of the ear are sometimes the sites for acupuncture-like TENS. The effects of TENS applied to the auricle are supported by the findings of Oliveri et al, [6] Krause et al, [7] and Noling et al. [8] They reported that application of high intensity, low frequency TENS to appropriate auricular acupuncture points increased experimental pain threshold. Paris et al reported significant results with the clinical application of auricular TENS in the treatment of ankle inversion sprains, [1] and Leo reported similar results in the treatment of pediatric reflex sympathetic dystrophy. [2] The purpose of our study was to examine the effect of bilateral auricular TENS on pain in patients experiencing distal extremity pain. This study was designed to test the hypothesis that a single treatment of acupuncture-like TENS to appropriate auricular points will significantly reduce pain associated with various distal extremity pathologies and injuries.

Literature Review

In recent years, Paul Nogier, a French neurologist who learned the Chinese way of acupuncture, delved more deeply into the correlation between auricular acupuncture points and physiological functions to augment the efficacy of auriculotherapy. [9] Nogier discovered that some of his patients had been treated successfully for sciatica with cauterization of a certain point on the external ear. [10] After performing clinical trials using different pathological conditions and various ear points, Nogier proposed that 1) the body surface and visceral structures are represented on the aurcile in a somatotopic organization that resembles an inverted fetus, 2) disease or pain of any body structure is reflected by increased tenderness and skin conductance at a corresponding point on the ear, and 3) electrical stimulation or acupuncture of the appropriate ear point leads to an abolition of or dramatic decrease in pain in the corresponding part of the body. [11]

The Chinese and Nogier systems were systematically compared for similarities and differences of auricular points representing musculoskeletal and sensory systems, internal organs and endocrine glands, peripheral and central nervous systems, and functional problems. Although basically the same, the Chinese and Nogier ear charts do vary in the somatotopic arrangement of a few points unrelated to distal extremities. [11]

Auricular points may be stimulated in a variety of ways. The most common type of ear acupuncture-point stimulation is needle insertion. [5,12] Other auriculotherapy techniques include ear stapling and acupressure [12]; TENS [6-8,12]; and moxibustion, ultrasound, and injection of various substances. [12,13]

Auriculotherapy has been effective in treating a variety of conditions. Recently, studies have shown that acupressure and acupuncture applied to certain ear points may aid in weight reduction [14]; smoking cessation [15]; and alleviation of symptoms of Meniere's disease, [16] alcoholism, [17] and cerebral palsy. [18] Chow and colleagues observed that auricular acupuncture had no effect in relieving symptoms of exercise-induced asthma. [19]

Although auriculotherapy may be used as a treatment for many disorders, its primary use if for pain relief. Paris and co-workers reported that auricular TENS, in conjunction with traditional physical therapy and electrical stimulation of certain body loci, decreased both pain and rehabilitation time in patients with ankle inversion sprains. [1] Kajdos reported that of 175 patients treated with ear acupuncture for migraine headaches, 89% received pain relief and 11% were unaffected. [4] Leung and Spoerel observed that most of their patients suffering from chronic intractable pain of various causes received at least partial pain relief from auricular acupuncture. [9] In a case report on the treatment of pediatric reflex sympathetic dystrophy, Leo reported that electrical stimulation delivered to the auricle alleviated symptoms. [2] Jichova and associates reported extinction of burning and pain sensations in patients with fresh burns of up to 30% of body surface area within 25 to 30 minutes after insertion of needles at the shen-men and thalamic projection points on the auricle. [20] Chun and Heather observed that 84% of their patients with chronic pain treated with electrical auriculotherapy received some pain relief. [21]

Numerous disadvantages exist in many of the current pain-management techniques. Surgical intervention is an invasive method leaving the patient vulnerable to possible infection and deforming, debilitating scars. Many drugs used for pain control are addictive and produce detrimental side effects. A noninvasive, nonaddictive pain-relieving technique applied to an area distant from the site of pain would be a welcome addition to present pain-management techniques. Auricular TENS is a clinical modality applied to points distant from the site of pain that may prove to be a beneficial pain-control technique.

Method

Subjects

Fifteen adult outpatients (6 men, 9 women) from several Birmingham health care facilities participated in this study, which involved treatment with either auricular acupuncture-like TENS or a "placebo" pill. The subjects ranged in age from 24 to 78 years with a mean age of 43.1 years. All subjects complained of distal extremity pain: seven with upper extremity pain and eight with lower extremity pain. The subjects' demographic characteristics are presented by group in Table 1. Criteria for patient participation in this study were 1) pain in the area of the distal upper extremity (elbow, wrist, or fingers) or the distal lower extremity (knee, ankle, or toes) experienced just before treatment, 2) acute pain of less than six months' duration, 3) no opiate pain medication for at least eight hours before treatment, and 4) 18 years of age or older. Individuals who were pregnant or had a cardiac pacemaker were not accepted for the study because TENS may be contraindicated under these conditions. [22] The subjects were naive to the specific auricular points to be stimulated. All subjects were aware that the anticipated outcome of the procedure was pain relief. Before implementation, this study was approved by the Institutional Review Board for Human Use at The University of Alabama at Birmingham. The study was also approved by the various Birmingham health care facilities.

Instrumentation

A Staodyn Insight (*1) electrostimulator was used to deliver TENS to auricular points. This unit was equipped with a spring-loaded probe tip with a diameter of about 1 mm for stimulation and a 5- X 4-cm rectangular dispersive electrode.

Procedure

The subjects were randomly assigned to an Experimental (n = 8) or a Control (placebo) (n = 7) Group. A brief medical history questionnaire was completed and a consent form was signed by each subject before the treatment. The visual analogue scale (VAS) [23-26] and the pain rating index (PRI) from the McGill Pain Questionnaire [27,28] were completed by all subjects immediately before treatment. All information was recorded and kept confidential.

Treatment for the Control Group consisted of taking a placebo pill, which was described to the subject as "a pill that has been used in the past for pain relief." The subject was then positioned supine on a treatment plinth for 40 minutes with pillows under the knees and the head and shoulders.

The Experimental Group subjects were positioned the same as the Control Group. Each subject received bilateral acupuncture-like (high intensity, low frequency) TENS to five points on the auricle of both ears: shen-men, lung, dermis (also referred to as the subcortex or thalamus point), and two points appropriate to the painful extremity (Fig. 1). The appropriate points for the upper extremity were elbow, wrist, and finger. The appropriate points for the lower extremity were knee, ankle, and toe. Appropriate points were chosen according to the painful area. The shen-men, lung, and dermis points are associated with analgesic or tranquilizing effects and used in the treatment of restlessness and excessive sensitivity. [2] The lung point is especially associated with the surface area of the body and is the main point for decreasing pain during incisions. [2]

All electrode placement sites were cleaned before treatment with isopropyl alcohol and cotton gauze to reduce skin resistance. The dispersive electrode, used as a ground, was held by the subject in either hand; the specific hand was not recorded. Any earrings and necklaces were removed from the subjects. Stimulation points were located before the treatment using acupuncture charts and by finding areas of decreased skin resistance with the aid of auditory or visual signals from the point-locator circuit of the Staodyn Insight electrostimulator. The physical location of the points stimulated on the auricle were recorded for each subject according to the involved area of the extremity. The auricular stimulus consisted of a positive (monophasic waveform) direct current with a maximum output of 1,000 [microamp] delivered in pulses of 1 Hz. A nonspecified stimulus pulse width was preset in the unit by the manufacturer. Each subject was instructed to verbally respond to changes in stimulus intensity. As the intensity of the stimulus was increased, the subject indicated the first moment the stimulus was felt by saying "Feel it" for the investigator (A.G.L.) to be aware of the subject's sensitivity. The stimulus was increased slowly to the subject's pain threshold when the subject said "Stop," after which no further increases in intensity were made. Each auricular point was stimulated 60 seconds, with the intensity maintained at the subject's threshold level. This treatment technique was similar to that used by Oliveri et al, [6] Krause et al, [7] and Noling et al [8] on healthy subjects.

Following the 10-minute treatment, the subjects remained in the treatment position for 30 minutes, during which time all subjects completed additional sets of pain questionnaires. All subjects completed pain scales at three posttest time intervals: immediately posttreatment, 10 minutes posttreatment, and 30 minutes posttreatment.

Criteria for Effectiveness

The VAS [23-26] and the PRI [27,28] were used to measure pain. The VAS contained all the scales for each subject on one sheet and required the subjects to place a vertical mark on a 10-cm line bounded by the phrases "no pain" on the left and "worst pain imaginable" on the right. [23-26] The PRI required the subjects to choose words that described their pain at the moment. The PRI, which has a maximum score of 78, is determined by summing the rank values of all the words chosen from 20 sets of qualitative words that describe the sensory, affective, and evaluative properties of pain. [27,28] Subjects were allowed to see their previously completed PRI at any point in the study, if requested.

Data Analysis

Descriptive statistics for the VAS and the PRI were calculated at each measurement time for the Experimental and Control Groups. A two-factor repeated-measures analysis of variance (ANOVA) was used to test the data for statistical significance. The two factors were group and time of measurement. An ANOVA was performed for the VAS and the PRI raw data. Each ANOVA was conducted using both a univariate and a multivariate approach. When the "symmetry" conditions were met, or when the univariate and multivariate ANOVA results agreed, the univariate ANOVA results were used, because the univariate approach is typically more powerful. [29]

Statistically significant group-by-time interactions were followed up with post hoc tests for simple main effects. Statistically significant simple main effects for time were followed up with the Tukey's Honestly Significant Difference (HSD) test. [30] To provide adequate statistical power, an alpha level of .10 was chosen as the criterion for statistical significance. The power of a statistical test is the probability that it will lead to the rejection of the null hypothesis. [31] Power is a function of alpha level, effect size, and sample size. Before analyzing the data, we estimated the power of the interaction test in the ANOVA to be .61 using an alpha level of .05, a "large" effect size of .40, and our fixed sample size of 15; using an alpha level of .10 increased power to .73. [31] We were more comfortable with a .73 chance of rejecting the null hypothesis than a .61 chance, so we chose the .10 alpha level. After pooling the data over all four measurement times (4 X 15 = 60 observations), a Pearson product-moment correlation coefficient was calculated between the VAS and the PRI.

To help assess clinical significance, the percentage of pain reduction was calculated for each subject at each posttreatment measurement time using the following formula:

% change = posttreatment value - basline value/baseline value X 100

The mean percentage of pain reduction was also calculated for each group at each posttreatment measurement time.

Results

Tables 2 and 3 present descriptive statistics for the VAS and the PRI, respectively. Figures 2 and 3 present the mean pain values for the Experimental and Control Groups using the VAS and the PRI, respectively.

The ANOVA results for the VAS are summarized in Table 4. Neither the univariate nor the multivariate test of the group-by-time interaction was statistically significant. The time main effect was statistically significant, indicating that the combined groups showed a reduction in pain over time. Because the group-by-time interaction was not significant, however, we found no different between the group profiles over time. The group main effect was not statistically significant.

The ANOVA results for the PRI are summarized in Table 5. The univariate test for the group-by-time interaction was not statistically significant. One of the symmetry conditions, however, was not met; therefore, the statistically significant multivariate test of interaction was used. Tests of simple main effects showed that the Experimental and Control Group mean pain values different significantly (p [is less than] .05) at each posttreatment measurement time but did not differ significantly at the baseline measurement. At each posttreatment measurement time, the Experimental Group mean was lower than the Control Group mean (Tab. 3, Fig. 3). Tests of simple main effects also showed that the means for the various measurement times differed significantly for the Experimental Group but not for the Control Group. For the Experimental Group, Tukey's HSD test showed that the baseline mean differed significantly (p [is less than] .05) from each of the posttreatment means, but that none of the posttreatment means differed significantly from each other. As shown in Table 3 and Figure 3, each posttreatment mean was lower than the baseline mean. The differences at the posttreatment measurement times can also be seen by comparing the differences between the mean percentages of pain reduction of the two groups (Tab. 6).

The Pearson product-moment correlation coefficient between the VAS and the PRI for pooled data ( 4 X 15 = 60) was .16. This value represents a weak positive relationship between the two measures.

The hypothesis of this study stated that a single treatment of acupuncture-like TENS to appropriate auricular points would significantly reduce pain associated with various distal extremity pathologies and injuries. This hypothesis was supported by the results for the PRI but not by the results for the VAS.

Discussion

The results for the PRI and the VAS are conflicting, but the results from the PRI alone suggest that a single treatment of auricular acupuncture-like TENS significantly reduced distal extremity pain of various etiologies. The results also suggest that the reduction in pain lasted for at least 30 minutes. Chun and Heather used electrical auriculotherapy on patients with chronic pain. Eighty-four percent of their patients received pain relief, as judged by subjective descriptions of pain in regard to severity, frequency of attack, and necessity of taking analgesics. [21] Leo used electrical auricular stimulation to treat a child with reflex sympathetic dystrophy and reported that symptoms were alleviated, as determined by physical examination and patient report. [2] In patients with ankle inversion sprains, Paris and associates used auricular TENS along with electrical stimulation of certain body loci and found decreases in pain, as rated on a subjective five-point scale, and decreased rehabilitation time. [1]

It is difficult to compare our results concerning the persistence of the treatment effect over time to the other auriculotherapy studies because of the very different methods used. The patient in the study by Leo received auricular stimulation treatments over a six-day period and was completely asymptomatic by the sixth day, with a follow-up three months later showing no increase in symptoms. [2] Patients in the study by Paris et al received several treatments over a 9- to 17-day period. [1] Although Paris et al conducted no follow-up to show any continued effects over an increased time period, the focus of their study was on difference in time of rehabilitation with the addition of the auricular treatment; pain was only one of many factors considered in criteria for release. Noling et al, using a method very similar to ours with healthy subjects, found that changes in mean experimental pain threshold after one auricular electrical stimulation treatment significantly increased between 0 and 10 minutes posttreatment and between 5 and 10 minutes posttreatment. The increase of mean pain threshold between 0 and 5 minutes posttreatment was not statistically significant. [8] Although indications are that the effects of auricular stimulation persist or even increase over time, more studies are needed to address this question specifically.

The results of this clinical study correlate with results of previous studies of experimentally induced pain in healthy subjects conducted at The University of Alabama at Birmingham. [6-8] Oliveri and co-workers stimulated appropriate ear points unilaterally for wrist pain and observed a significant increase in experimental pain threshold. [6] Krause and associates stimulated appropriate auricular points corresponding to the wrist and reported significant increases in experimentally induced pain threshold with unilateral and bilateral stimulation. [7] Noling and colleagues observed that elevations in experimental pain threshold after auricular stimulation to points appropriate for wrist pain lasted at least 10 minutes poststimulation, [8] as previously discussed.

The correlation between the VAS and the PRI was weak in this study. Many possible explanations exist for this poor relationship. The sex of the subjects may have affected the correlation of the two pain measures, and some subjects may have had poor understanding of what the pain questionnaire required. Kroth, [32] Janke, [33] and Neighbors et al [34] reported strong correlations between the VAS and the PRI in young, adult, college-educated female subjects. Our subjects were older and consisted of men and women, and their level of education was unknown. The age range for subjects in this study was 24 to 78 years, approximately six decades, offering another possible reason for a poor correlation.

The differences obtained between the two groups in this study were small but indicate that the use of auricular acupuncture-like TENS for distal extremity pain was more effective than a placebo pill. The age and sex differences betwee the two groups and the small sample size limit our ability to generalize the conclusions to a large population. In addition, there was unequal sampling with reference to the involved extremity. Only two Experimental Group subjects had pain in the upper extremity, whereas five Control Group subjects had upper extremity pain. To assess the value of auricular TENS on pain, additional clinical studies are necessary using better control of sampling distribution of the following factors: age, sex, and involved extremity.

Conclusions

In a small group of subjects experiencing distal extremity pain, statistically significant pain reduction occurred after application of high intensity, low frequency TENS to auricular acupuncture points. These results suggest that bilateral auricular stimulation may be an effective analgesic technique for distal extremity pain. Although few well-controlled studies have been conducted regarding the efficacy of auricular TENS for pain management, these studies do suggest this technique may be a viable alternative to invasive or addictive methods of pain management. Further research is necessary to substantiate the results of these studies and to further explore the therapeutic efficacy of this technique.

(*1) Staodynamics, Inc, PO Box 1379, Longmont, CO 80501.

References

[1] Paris DL, Baynes F, Gucker B: Effect of the Neuroprobe in the treatment of second-degree ankle inversion sprains. Phys Ther 63:35-40, 1983

[2] Leo KC: Use of electrical stimulation at acupuncture points for the treatment of reflex sympathetic dystrophy in a child: A case report. Phys Ther 63:957-959, 1983

[3] Sjolund BH, Eriksson MBE: Electroacupuncture and endogenous morphines. (Letter to the editor.) Lancet 2:1085, 1976

[4] Kajdos V: Experiences with auricular acupuncture. American Journal of Acupuncture 4:130-136, 1976

[5] Kitade T, Hyodo M: The effects of stimulation of ear acupuncture points on the body's pain threshold. Am J Chin Med 7:241-252, 1979

[6] Oliveri AC, Clelland JA, Jackson J, et al: Effects of auricular transcutaneous electrical nerve stimulation on experimental pain threshold. Phys Ther 66:12-16, 1986

[7] Krause AW, Clelland JA, Knowles CJ, et al: Effects of unilateral and bilateral auricular transcutaneous electrical nerve stimulation on cutaneous pain threshold. Phys Ther 67:507-511, 1987

Effects of Auricular Transcutaneous Electrical Nerve Stimulation on Distal Extremity Pain: A Pilot Study Pain has plagued the human species for centuries. Approaches to pain management have evolved and changed over the years, but some modern methods correlate with methods used many years ago. Many
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modern analgesic methods are undesirable or detrimental such as surgery, which is invasive, or use of drugs, which may be addictive. Physical therapists often administer pain-relieving treatments to patients suffering from pain of various etiologies. A noninvasive technique that can relieve distal extremity pain of various etiologies would be a welcome addition to current treatment techniques.

Transcutaneous electrical nerve stimulation is a noninvasive and nonaddictive treatment for pain used by many physical therapists. Recent clinical studies have reported significant decreases in pain following the application of high intensity, low frequency TENS [1,2] and electroacupuncture. [3-5] High intensity, low frequency TENS applied over acupuncture points is referred to as "acupuncture-like" TENS. Acupuncture points on the auricle of the ear are sometimes the sites for acupuncture-like TENS. The effects of TENS applied to the auricle are supported by the findings of Oliveri et al, [6] Krause et al, [7] and Noling et al. [8] They reported that application of high intensity, low frequency TENS to appropriate auricular acupuncture points increased experimental pain threshold. Paris et al reported significant results with the clinical application of auricular TENS in the treatment of ankle inversion sprains, [1] and Leo reported similar results in the treatment of pediatric reflex sympathetic dystrophy. [2] The purpose of our study was to examine the effect of bilateral auricular TENS on pain in patients experiencing distal extremity pain. This study was designed to test the hypothesis that a single treatment of acupuncture-like TENS to appropriate auricular points will significantly reduce pain associated with various distal extremity pathologies and injuries.

Literature Review

In recent years, Paul Nogier, a French neurologist who learned the Chinese way of acupuncture, delved more deeply into the correlation between auricular acupuncture points and physiological functions to augment the efficacy of auriculotherapy. [9] Nogier discovered that some of his patients had been treated successfully for sciatica with cauterization of a certain point on the external ear. [10] After performing clinical trials using different pathological conditions and various ear points, Nogier proposed that 1) the body surface and visceral structures are represented on the aurcile in a somatotopic organization that resembles an inverted fetus, 2) disease or pain of any body structure is reflected by increased tenderness and skin conductance at a corresponding point on the ear, and 3) electrical stimulation or acupuncture of the appropriate ear point leads to an abolition of or dramatic decrease in pain in the corresponding part of the body. [11]

The Chinese and Nogier systems were systematically compared for similarities and differences of auricular points representing musculoskeletal and sensory systems, internal organs and endocrine glands, peripheral and central nervous systems, and functional problems. Although basically the same, the Chinese and Nogier ear charts do vary in the somatotopic arrangement of a few points unrelated to distal extremities. [11]

Auricular points may be stimulated in a variety of ways. The most common type of ear acupuncture-point stimulation is needle insertion. [5,12] Other auriculotherapy techniques include ear stapling and acupressure [12]; TENS [6-8,12]; and moxibustion, ultrasound, and injection of various substances. [12,13]

Auriculotherapy has been effective in treating a variety of conditions. Recently, studies have shown that acupressure and acupuncture applied to certain ear points may aid in weight reduction [14]; smoking cessation [15]; and alleviation of symptoms of Meniere's disease, [16] alcoholism, [17] and cerebral palsy. [18] Chow and colleagues observed that auricular acupuncture had no effect in relieving symptoms of exercise-induced asthma. [19]

Although auriculotherapy may be used as a treatment for many disorders, its primary use if for pain relief. Paris and co-workers reported that auricular TENS, in conjunction with traditional physical therapy and electrical stimulation of certain body loci, decreased both pain and rehabilitation time in patients with ankle inversion sprains. [1] Kajdos reported that of 175 patients treated with ear acupuncture for migraine headaches, 89% received pain relief and 11% were unaffected. [4] Leung and Spoerel observed that most of their patients suffering from chronic intractable pain of various causes received at least partial pain relief from auricular acupuncture. [9] In a case report on the treatment of pediatric reflex sympathetic dystrophy, Leo reported that electrical stimulation delivered to the auricle alleviated symptoms. [2] Jichova and associates reported extinction of burning and pain sensations in patients with fresh burns of up to 30% of body surface area within 25 to 30 minutes after insertion of needles at the shen-men and thalamic projection points on the auricle. [20] Chun and Heather observed that 84% of their patients with chronic pain treated with electrical auriculotherapy received some pain relief. [21]

Numerous disadvantages exist in many of the current pain-management techniques. Surgical intervention is an invasive method leaving the patient vulnerable to possible infection and deforming, debilitating scars. Many drugs used for pain control are addictive and produce detrimental side effects. A noninvasive, nonaddictive pain-relieving technique applied to an area distant from the site of pain would be a welcome addition to present pain-management techniques. Auricular TENS is a clinical modality applied to points distant from the site of pain that may prove to be a beneficial pain-control technique.

Method

Subjects

Fifteen adult outpatients (6 men, 9 women) from several Birmingham health care facilities participated in this study, which involved treatment with either auricular acupuncture-like TENS or a "placebo" pill. The subjects ranged in age from 24 to 78 years with a mean age of 43.1 years. All subjects complained of distal extremity pain: seven with upper extremity pain and eight with lower extremity pain. The subjects' demographic characteristics are presented by group in Table 1. Criteria for patient participation in this study were 1) pain in the area of the distal upper extremity (elbow, wrist, or fingers) or the distal lower extremity (knee, ankle, or toes) experienced just before treatment, 2) acute pain of less than six months' duration, 3) no opiate pain medication for at least eight hours before treatment, and 4) 18 years of age or older. Individuals who were pregnant or had a cardiac pacemaker were not accepted for the study because TENS may be contraindicated under these conditions. [22] The subjects were naive to the specific auricular points to be stimulated. All subjects were aware that the anticipated outcome of the procedure was pain relief. Before implementation, this study was approved by the Institutional Review Board for Human Use at The University of Alabama at Birmingham. The study was also approved by the various Birmingham health care facilities.

Instrumentation

A Staodyn Insight (*1) electrostimulator was used to deliver TENS to auricular points. This unit was equipped with a spring-loaded probe tip with a diameter of about 1 mm for stimulation and a 5- X 4-cm rectangular dispersive electrode.

Procedure

The subjects were randomly assigned to an Experimental (n = 8) or a Control (placebo) (n = 7) Group. A brief medical history questionnaire was completed and a consent form was signed by each subject before the treatment. The visual analogue scale (VAS) [23-26] and the pain rating index (PRI) from the McGill Pain Questionnaire [27,28] were completed by all subjects immediately before treatment. All information was recorded and kept confidential.

Treatment for the Control Group consisted of taking a placebo pill, which was described to the subject as "a pill that has been used in the past for pain relief." The subject was then positioned supine on a treatment plinth for 40 minutes with pillows under the knees and the head and shoulders.

The Experimental Group subjects were positioned the same as the Control Group. Each subject received bilateral acupuncture-like (high intensity, low frequency) TENS to five points on the auricle of both ears: shen-men, lung, dermis (also referred to as the subcortex or thalamus point), and two points appropriate to the painful extremity (Fig. 1). The appropriate points for the upper extremity were elbow, wrist, and finger. The appropriate points for the lower extremity were knee, ankle, and toe. Appropriate points were chosen according to the painful area. The shen-men, lung, and dermis points are associated with analgesic or tranquilizing effects and used in the treatment of restlessness and excessive sensitivity. [2] The lung point is especially associated with the surface area of the body and is the main point for decreasing pain during incisions. [2]

All electrode placement sites were cleaned before treatment with isopropyl alcohol and cotton gauze to reduce skin resistance. The dispersive electrode, used as a ground, was held by the subject in either hand; the specific hand was not recorded. Any earrings and necklaces were removed from the subjects. Stimulation points were located before the treatment using acupuncture charts and by finding areas of decreased skin resistance with the aid of auditory or visual signals from the point-locator circuit of the Staodyn Insight electrostimulator. The physical location of the points stimulated on the auricle were recorded for each subject according to the involved area of the extremity. The auricular stimulus consisted of a positive (monophasic waveform) direct current with a maximum output of 1,000 [microamp] delivered in pulses of 1 Hz. A nonspecified stimulus pulse width was preset in the unit by the manufacturer. Each subject was instructed to verbally respond to changes in stimulus intensity. As the intensity of the stimulus was increased, the subject indicated the first moment the stimulus was felt by saying "Feel it" for the investigator (A.G.L.) to be aware of the subject's sensitivity. The stimulus was increased slowly to the subject's pain threshold when the subject said "Stop," after which no further increases in intensity were made. Each auricular point was stimulated 60 seconds, with the intensity maintained at the subject's threshold level. This treatment technique was similar to that used by Oliveri et al, [6] Krause et al, [7] and Noling et al [8] on healthy subjects.

Following the 10-minute treatment, the subjects remained in the treatment position for 30 minutes, during which time all subjects completed additional sets of pain questionnaires. All subjects completed pain scales at three posttest time intervals: immediately posttreatment, 10 minutes posttreatment, and 30 minutes posttreatment.

Criteria for Effectiveness

The VAS [23-26] and the PRI [27,28] were used to measure pain. The VAS contained all the scales for each subject on one sheet and required the subjects to place a vertical mark on a 10-cm line bounded by the phrases "no pain" on the left and "worst pain imaginable" on the right. [23-26] The PRI required the subjects to choose words that described their pain at the moment. The PRI, which has a maximum score of 78, is determined by summing the rank values of all the words chosen from 20 sets of qualitative words that describe the sensory, affective, and evaluative properties of pain. [27,28] Subjects were allowed to see their previously completed PRI at any point in the study, if requested.

Data Analysis

Descriptive statistics for the VAS and the PRI were calculated at each measurement time for the Experimental and Control Groups. A two-factor repeated-measures analysis of variance (ANOVA) was used to test the data for statistical significance. The two factors were group and time of measurement. An ANOVA was performed for the VAS and the PRI raw data. Each ANOVA was conducted using both a univariate and a multivariate approach. When the "symmetry" conditions were met, or when the univariate and multivariate ANOVA results agreed, the univariate ANOVA results were used, because the univariate approach is typically more powerful. [29]

Statistically significant group-by-time interactions were followed up with post hoc tests for simple main effects. Statistically significant simple main effects for time were followed up with the Tukey's Honestly Significant Difference (HSD) test. [30] To provide adequate statistical power, an alpha level of .10 was chosen as the criterion for statistical significance. The power of a statistical test is the probability that it will lead to the rejection of the null hypothesis. [31] Power is a function of alpha level, effect size, and sample size. Before analyzing the data, we estimated the power of the interaction test in the ANOVA to be .61 using an alpha level of .05, a "large" effect size of .40, and our fixed sample size of 15; using an alpha level of .10 increased power to .73. [31] We were more comfortable with a .73 chance of rejecting the null hypothesis than a .61 chance, so we chose the .10 alpha level. After pooling the data over all four measurement times (4 X 15 = 60 observations), a Pearson product-moment correlation coefficient was calculated between the VAS and the PRI.

To help assess clinical significance, the percentage of pain reduction was calculated for each subject at each posttreatment measurement time using the following formula:

% change = posttreatment value - basline value/baseline value X 100

The mean percentage of pain reduction was also calculated for each group at each posttreatment measurement time.

Results

Tables 2 and 3 present descriptive statistics for the VAS and the PRI, respectively. Figures 2 and 3 present the mean pain values for the Experimental and Control Groups using the VAS and the PRI, respectively.

The ANOVA results for the VAS are summarized in Table 4. Neither the univariate nor the multivariate test of the group-by-time interaction was statistically significant. The time main effect was statistically significant, indicating that the combined groups showed a reduction in pain over time. Because the group-by-time interaction was not significant, however, we found no different between the group profiles over time. The group main effect was not statistically significant.

The ANOVA results for the PRI are summarized in Table 5. The univariate test for the group-by-time interaction was not statistically significant. One of the symmetry conditions, however, was not met; therefore, the statistically significant multivariate test of interaction was used. Tests of simple main effects showed that the Experimental and Control Group mean pain values different significantly (p [is less than] .05) at each posttreatment measurement time but did not differ significantly at the baseline measurement. At each posttreatment measurement time, the Experimental Group mean was lower than the Control Group mean (Tab. 3, Fig. 3). Tests of simple main effects also showed that the means for the various measurement times differed significantly for the Experimental Group but not for the Control Group. For the Experimental Group, Tukey's HSD test showed that the baseline mean differed significantly (p [is less than] .05) from each of the posttreatment means, but that none of the posttreatment means differed significantly from each other. As shown in Table 3 and Figure 3, each posttreatment mean was lower than the baseline mean. The differences at the posttreatment measurement times can also be seen by comparing the differences between the mean percentages of pain reduction of the two groups (Tab. 6).

The Pearson product-moment correlation coefficient between the VAS and the PRI for pooled data ( 4 X 15 = 60) was .16. This value represents a weak positive relationship between the two measures.

The hypothesis of this study stated that a single treatment of acupuncture-like TENS to appropriate auricular points would significantly reduce pain associated with various distal extremity pathologies and injuries. This hypothesis was supported by the results for the PRI but not by the results for the VAS.

Discussion

The results for the PRI and the VAS are conflicting, but the results from the PRI alone suggest that a single treatment of auricular acupuncture-like TENS significantly reduced distal extremity pain of various etiologies. The results also suggest that the reduction in pain lasted for at least 30 minutes. Chun and Heather used electrical auriculotherapy on patients with chronic pain. Eighty-four percent of their patients received pain relief, as judged by subjective descriptions of pain in regard to severity, frequency of attack, and necessity of taking analgesics. [21] Leo used electrical auricular stimulation to treat a child with reflex sympathetic dystrophy and reported that symptoms were alleviated, as determined by physical examination and patient report. [2] In patients with ankle inversion sprains, Paris and associates used auricular TENS along with electrical stimulation of certain body loci and found decreases in pain, as rated on a subjective five-point scale, and decreased rehabilitation time. [1]

It is difficult to compare our results concerning the persistence of the treatment effect over time to the other auriculotherapy studies because of the very different methods used. The patient in the study by Leo received auricular stimulation treatments over a six-day period and was completely asymptomatic by the sixth day, with a follow-up three months later showing no increase in symptoms. [2] Patients in the study by Paris et al received several treatments over a 9- to 17-day period. [1] Although Paris et al conducted no follow-up to show any continued effects over an increased time period, the focus of their study was on difference in time of rehabilitation with the addition of the auricular treatment; pain was only one of many factors considered in criteria for release. Noling et al, using a method very similar to ours with healthy subjects, found that changes in mean experimental pain threshold after one auricular electrical stimulation treatment significantly increased between 0 and 10 minutes posttreatment and between 5 and 10 minutes posttreatment. The increase of mean pain threshold between 0 and 5 minutes posttreatment was not statistically significant. [8] Although indications are that the effects of auricular stimulation persist or even increase over time, more studies are needed to address this question specifically.

The results of this clinical study correlate with results of previous studies of experimentally induced pain in healthy subjects conducted at The University of Alabama at Birmingham. [6-8] Oliveri and co-workers stimulated appropriate ear points unilaterally for wrist pain and observed a significant increase in experimental pain threshold. [6] Krause and associates stimulated appropriate auricular points corresponding to the wrist and reported significant increases in experimentally induced pain threshold with unilateral and bilateral stimulation. [7] Noling and colleagues observed that elevations in experimental pain threshold after auricular stimulation to points appropriate for wrist pain lasted at least 10 minutes poststimulation, [8] as previously discussed.

The correlation between the VAS and the PRI was weak in this study. Many possible explanations exist for this poor relationship. The sex of the subjects may have affected the correlation of the two pain measures, and some subjects may have had poor understanding of what the pain questionnaire required. Kroth, [32] Janke, [33] and Neighbors et al [34] reported strong correlations between the VAS and the PRI in young, adult, college-educated female subjects. Our subjects were older and consisted of men and women, and their level of education was unknown. The age range for subjects in this study was 24 to 78 years, approximately six decades, offering another possible reason for a poor correlation.

The differences obtained between the two groups in this study were small but indicate that the use of auricular acupuncture-like TENS for distal extremity pain was more effective than a placebo pill. The age and sex differences betwee the two groups and the small sample size limit our ability to generalize the conclusions to a large population. In addition, there was unequal sampling with reference to the involved extremity. Only two Experimental Group subjects had pain in the upper extremity, whereas five Control Group subjects had upper extremity pain. To assess the value of auricular TENS on pain, additional clinical studies are necessary using better control of sampling distribution of the following factors: age, sex, and involved extremity.

Conclusions

In a small group of subjects experiencing distal extremity pain, statistically significant pain reduction occurred after application of high intensity, low frequency TENS to auricular acupuncture points. These results suggest that bilateral auricular stimulation may be an effective analgesic technique for distal extremity pain. Although few well-controlled studies have been conducted regarding the efficacy of auricular TENS for pain management, these studies do suggest this technique may be a viable alternative to invasive or addictive methods of pain management. Further research is necessary to substantiate the results of these studies and to further explore the therapeutic efficacy of this technique.

(*1) Staodynamics, Inc, PO Box 1379, Longmont, CO 80501.

References

[1] Paris DL, Baynes F, Gucker B: Effect of the Neuroprobe in the treatment of second-degree ankle inversion sprains. Phys Ther 63:35-40, 1983

[2] Leo KC: Use of electrical stimulation at acupuncture points for the treatment of reflex sympathetic dystrophy in a child: A case report. Phys Ther 63:957-959, 1983

[3] Sjolund BH, Eriksson MBE: Electroacupuncture and endogenous morphines. (Letter to the editor.) Lancet 2:1085, 1976

[4] Kajdos V: Experiences with auricular acupuncture. American Journal of Acupuncture 4:130-136, 1976

[5] Kitade T, Hyodo M: The effects of stimulation of ear acupuncture points on the body's pain threshold. Am J Chin Med 7:241-252, 1979

[6] Oliveri AC, Clelland JA, Jackson J, et al: Effects of auricular transcutaneous electrical nerve stimulation on experimental pain threshold. Phys Ther 66:12-16, 1986

[7] Krause AW, Clelland JA, Knowles CJ, et al: Effects of unilateral and bilateral auricular transcutaneous electrical nerve stimulation on cutaneous pain threshold. Phys Ther 67:507-511, 1987

[8] Noling LB, Clelland JA, Jackson JR, et al: Effect of transcutaneous electrical nerve stimulation at auricular points on experimental cutaneous pain threshold. Phys Ther 68:328-332, 1988

[9] Leung CY, Spoerel WE: Effect of auriculo-acupuncture on pain. Am J Chin Med 2: 247-260, 1974

[10] Oleson TD, Kroening RJ: A comparison of Chinese and Nogier auricular acupuncture points. American Journal of Acupuncture 11:205-233, 1983

[11] Nogier PFM: Treatise of Auriculotherapy. Maisonneuve, France, Moulin-les-Metz, 1972

[12] Chan P: Ear Acupressure. Monterey Park, CA, Chan's Corporation, 1981, pp 13-18, 33-37

[13] Lee TN: Lidocaine injections in auricular acupuncture: Treatment and tonification. American Journal of Acupuncture 5:137-143, 1977

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A Longobardi, MS, is Staff Physical Therapist, St Vincent's Hospital, 2701 9th Ct S, Birmingham, AL 35205. He was a gradute student, Division of Physical Therapy, School of Health Related Professions, The University of Alabama at Birmingham, Birmingham, AL 35294, when this study was conducted. This study was completed in partial fulfillment of the requirements for Mr Longobardi's master's degree at The University of Alabama at Birmingham. Address correspondence to 7709-G Eastridge Circle, Birmingham, AL 35210 (USA).

J Clelland, MS, is Associate Professor and Associate Director, Division of Physical Therapy, School of Health Related Professions, The University of Alabama at Birmingham.

C Knowles, MS, is Assistant Professor, Division of Physical Therapy, School of Health Related Professions, The University of Alabama at Birmingham.

J JAckson, PhD, is Assistant Professor, Office of Educational Development, School of Medicine, The University of Alabama at Birmingham.

This article was submitted February 13, 1987; was with the authors for revision for 47 weeks; and was accepted August 15, 1988.