43
Pain, 42 (1990) 43-48 Elsevier PAIN 01629
Pain relief achieved by transcutaneous electrical nerve stimulation and/or vibratory stimulation in a case of painful legs and moving toes R. Guieu a, M.F. Tardy-Gervet
‘, 0. Blin b and J. Pouget
b
’ LQbwatoire de Neurobiobgie Humaine, U.R.A. C.N.R.S. 372, Centre Scientifque de St. JPrcime, MarseiNes (France), and b Clinique des Maladies du Sy.&me Nerueux, C.H. U. Timone, Marseilles (France) (Received 8 December 1989, revision received 3 March 1990, accepted 6 March 1990)
A patient is described with painful legs and moving toes. The pain had been occurring for more than 15 years, and a Summary variety of therapies had been attempted with only partial, if any, success. Only morphine had succeeded in relieving the pain, but it had to be discontinued to avoid tolerance and dependence. We devised a treatment consisting of transcutaneous electrical nerve stimulation (TENS), vibratory stimulation (VS), and a combination of the two methods (TENS f VS). TENS brought about partial pain relief, but was less effective than VS; dual stimulation (TENS + VS) led to complete alleviation of the pain. Four months later, the patient was applying dual stimulation himself at home and was thus able to maintain complete retief with 3 or 4 weekly sessions. We suggest that dual stimulation results in a large-scale recruitment of large-diameter afferent fibres and may thus set up a powerful inhibitory control of nociception in our patient. Key war&r Pam; Involuntary movements; Toes; Vibratory stimulation (VS); Transcutaneous Dual stimulation (TENS + VS)
Inaction The syndrome combining leg pain and involuntary toe movements was first described in 1971 [27]. This rare pathology has been observed in patients who have previously suffered from lumbosacral spine disease [25], lumbago and sciatica [C&22,25,29],or sustained minor lumbar spine injury [27]. Some authors have also reported the occurrence of this syndrome after peripheral nerve lesions [21] and herpes roster infection [25]. The
Correspondence to: R. Guieu, Universitt d’Aix-Marseille I, Laboratoire de Neurobiologie Humaine, U.R.A. C.N.R.S. 372, Avenue Escadrille Normandie N&men, 13397 Marseilles Cedex 13, France.
electrical nerve stimulation (TENS);
disorder can affect either one or both legs. The occurrence of a similar syndrome affecting the arms has been reported, but this is rare [28]. The pain, which usually occurs in the forefoot or the lower third of the limb is diffuse but intense, resembling causalgia. It is sometimes accompanied by paraesthesia, and in most cases the pain develops before the toe movements [25]. The pain can occur anything from a few weeks to several years after a trauma, but no obvious link is usually found between the two. It can be either alleviated or aggravated by walking or standing, whereas the toe movements can sometimes be relieved by performing active arm movements [27]. The pain does not seem to be linked to the muscle contraction, since it persists when the movements have stopped. The patients’ sleeping patterns are
0304-3959/90/$03.50 0 1990 Elsevier Science Publishers B.V. (Biomedical Division)
44
consistently disturbed by insomnia or a decrease in rapid eye movement sleep [21]. The toe movements sometimes continue at night and even increase during the REM phase [27]. Depressive reactions are frequent. Apart from those cases where the syndrome is associated with peripheral neuropathy, it sometimes involves a decrease in the amplitude of sensory potentials [27], while histological investigations have shown the existence of discrete signs suggesting segmental demyelinisation [27]. In most cases, however, the results of electrophysiological and histological studies of the nerve have been normal. The electromyographic recordings of the movements resembled those obtained during voluntary contractions and were found to involve not only the intrinsic toe muscles but also the common extensor and the toe flexor muscles. The present article reports the treatment of a particularly difficult case, using electrical and/or vibratory stimulation, which are known to be efficient means of relieving chronic pain [2,5,7,8,1113,15,16,18,20].
Case report and methods Mr. Jean D., aged 29, was admitted to hospital in April 1986 complaining of chronic intermittent pain in his right forefoot. In 1965, at the age of 6, Mr. D. was injured in a street accident and sustained cranial trauma, fractures of the pelvis and both legs, and lesion of the right sciatic nerve, mainly of the peroneal branch. At about the age of 10, he began to develop pains in the forefoot, characterised by burning sensations which gradually worsened over the months. In 1974 (age 15) the patient underwent a posterior leg tendon transplantation to compensate for defective 2nd, 3rd, and 4th right toe extensors. During the subsequent months, the symptoms increased to several attacks per week; before long, these were also accompanied by involuntary movements in the 3 middle toes. The pain was deep, seemingly in the bones, resembled burning or twisting, and became worse at night, causing intractable insomnia. Since treatment with conventional analgesics and anxiolytics was unsuccessful, a lumbar sympathetic
block was applied, which relieved the pain for several hours and the toe movements for 1 week. When this patient was admitted to hospital in April 1986, he still showed spontaneous toe movements including extension of the 2nd toe and abduction of the 3rd and 4th toes in the right foot and complained of distressing pain in the toes and forefoot extending up the antero-lateral side of the ankle. On examination, he was found to have diminished sensibility in the region of the right peroneal nerve and no Achilles tendon reflex, but no motor deficits were observed. Some cutaneous trophic changes were visible on his forefoot. In addition to continuous background pain, he suffered from several paroxysmal attacks per week which induced insomnia. The pain could be alleviated by standing, walking and consumption of alcohol, whereas coffee, changes in the weather and emotional distress were aggravating factors. Conventional analgesics and carbamazepine did not relieve the pain, whereas intravenous perfusions of clonazepam (3 mg/day) associated with amitriptyline (100 mg/day) gave temporary relief. Since the frequency of the attacks increased over the next few months and the pain was becoming more intense, treatment was undertaken with morphine derivatives. These were administered orally at first in the form of morphine sulphate (60 mg when attacks occurred), but it was soon decided to inject morphine hydrochloride (2 -3 7 mg injections per week, depending on the frequency of the attacks), alternating with corticosteroid injections. This treatment stopped both the pain and the movements, but had to be discontinued to avoid tolerance and dependency; the morphine doses were therefore gradually decreased. An external electrical stimulator delivering a lowfrequency, high-intensity current was used at this stage, along with barbiturates (secobarbital, 200 mg/day), and antidepressants (amitriptyline, 150 mg/day), which provided the patient with effective pain relief during the morphine withdrawal period, which lasted for several months. After a further 4-5 months, however, both the pain and the toe movements returned, and the patient was re-admitted to hospital in May, 1989, suffering from daily attacks. Clinical examination showed no change. The painful attacks accompa-
45
nied by toe movements took place in a context of continuous background pain. The pain arose on the dorsal surface of the 2nd, 3rd and 4th toes and extended along the forefoot and up the anterolateral side of the ankle. Despite the prescription of 30 mg of nitrazepam, the attacks always caused severe insomnia. An electromyogram showed the presence of extensive denervating lesions in the right tibialis anterior muscle. The motor conduction velocity of the tibial and peroneal nerves was normal, but the amplitude of the right sural nerve sensory potentials had decreased. No morphological abnormalities were noted in the sural nerve biopsy. Before resorting to internal stimulation of the posterior columns, it was decided to attempt to relieve the pain by means of vibratory stimulation and/or transcutaneous electrical nerve stimulation. The electrical stimulation (TENS) was applied with a stimulator delivering biphasic pulses with a duration of 0.26 msec at a frequency of 100 Hz. Four electrodes connected to 2 channels were used. One electrode was placed on the dorsal surface of the 2nd, 3rd and 4th toes, one above the instep opposite the tibial nerve, another one-third of the distance up the leg on the anterolateral side, and the last in the popliteal fossa, over the peroneal nerve. The current intensity was chosen by the patient himself, below the pain threshold. It was strong enough to produce paraesthesia and toe and ankle movements by recruiting muscular fibres the interosseus and lateral peroneal among muscles. The vibratory stimulation (VS; frequency 100 Hz, amplitude 0.5 mm), was applied by means of a prototype consisting of a motor equipped with an eccentric mass, set on a plastic base covered with a fine layer of rubber, which served as an applicator. The surface area of the applicator was 60 cm*. After several trials, the strongest analgesic effects were found to be achieved with vibrations applied to the plantar surface of the forefoot with a pressure of approximately 10 g/cm*. It is worth noting that considerable erythema occurred around the site of stimulation by the end of the session, particularly in the case of the vibratory stimulation.
Placebo treatment consisted of placing the electrical stimulation electrodes at the appropriate points simulating a TENS session, without switching on the current. Here the patient was told that he would be unable to feel anything because the current intensity was too low. Experimental procedure: seven 30 min sessions were run (see Table I): two with electrical stimulation (TENS), two with vibratory stimulation (VS), two with both electrical and vibratory stimulation (TENS + VS), and one placebo session. They were run in a pseudo-random order, and the minimum time allowed to elapse between any 2 successive sessions was 72 h. The pain levels were measured on a uisual anaiogue scale (VAS) and a &point verbal scale, consisting of: no pain, mild pain, discomforting pain, distressing pain, horrible pain, excruciating pain. The patient was requested to rate his pain on both scales before the session began, immediately after the session, and again 4, 24, 48 and 72 h after the session. The pain rating was measured on the visual scale in millimeters (from 0 to 100) and on the verbal scale in terms of the rank’ of the adjective chosen. If the patient hesitated between two adjacent adjectives, the mean rank between the two was recorded. On leaving hospital, the patient continued to apply combined stimulation (TENS + VS) himself on a regular basis.
Results The results are presented in the form of a diagram showing changes in pain intensity as a function of time. The pain intensities obtained on the visual analogue scale (Fig. 1A) were averaged between the 2 sessions run under each type of treatment (TENS, VS, TENS + VS). The placebo value corresponds to a single session. It can be seen that the analgesic effects obtained were stronger with the combined technique (TENS + VS) than with either method alone. The combined method was, moreover, the only one which resulted in complete pain relief by the end of the session (Fig. 1A). In addition, the relief was long-
46 A loo-
PLKEt33
80 -
TENS
x .C $
60-
VS
E -5 0_
40-
20 TENS N
0-
I
0
+ VS
1
40mn
1 4h
12h
24h
I
48h
72h
B
Discussion
54-
:
3-
6 .c c
2-
a” 1-
0"
The data obtained on the verbal scale were in agreement with those recorded on the visual analogue scale (Fig. 1B). This was confirmed by the satisfactory degree of correlation (Spearman rank analysis) found to exist between the two intensity ratings (R = 0.73, P -c 0.001). Four months after the patient started self-treatment at home, 3-4 sessions of combined stimulation per week sufficed to relieve his pain completely. In addition, the involuntary toe movements disappeared. He continues to use nitrazepam, 5 mg at bedtime as a hypnotic.
TENS
. VS
,
r
0
40mn
4h
12h
24h
48h
72h
Fig. 1. Changes in pain intensity assessed after each of the 3 types of treatment (TENS, VS and TENS+VS) and the placebo. The pain intensity was measured on a visual analogue scale (A) and on a 6-point verbal scale (B). The various times at which the pain was assessed are given on the abscissa. Time TO is that corresponding to the pain level before treatment. The various points on the 3 curves (TENS+VS, VS, TENS) are the means between the 2 treatment sessions. On the placebo curve, however, each point represents a single value.
lasting, since the pain returned only after 24 h on average after the treatment session, and after 48 h had developed only 40% of its previous intensity. The results obtained with the visual analogue scale were processed statistically. The results of the Wilcoxon test showed that the combined method was significantly more effective than either VS (P = 0.001) or TENS (P = 0.001) alone. On the other hand, VS had significantly stronger analgesic effects than TENS (P = 0.004). All 3 therapeutic methods had significantly stronger effects than the placebo (P < 0.02).
Our patient presented with a classical case of what has been called the ‘painful legs and moving toes’ syndrome [21,22,24,25,27,29]; he was as difficult to treat as those patients described by other authors [6,21,22,24,25,27,29]. The excellent results of the combined stimulation, which resulted in total and long-lasting pain alleviation and abolished the toe movements, is certainly worth noting. The physiopathology of this syndrome has given rise to much debate as to the origin of the pain and the toe movements. Nathan et al. [22] believe them to be due to the activation of afferent fibres in the posterior nerve roots, which triggers signals to interneuronal circuits and to motoneurones. The exact relationship between the pain and the toe movements is difficult to establish, however, since the former can occur in the absence of the latter. Spillane et al. [27] have suggested that the pain may be caused by impairment of the sympathetic nervous system. It is difficult to explain, however, why sympathectomy has failed to relieve the pain, whereas blocking the sympathetic ganglia by local ganglionic injections of anaesthetic or phenol has led to remittance of the symptoms for several hours [27, the present case]. Some authors have hypothesised central and others peripheral mechanisms. According to Schoenen et al. [24]: ‘Painful legs and moving toes are not a homogenous entity, but a syndrome of diverse causes.’ In the case of our patient, there was certainly some clinical evidence (a case history involving
47
TABLE ORDER
I OF SESSIONS
DURING
THE 21 DAY PERIOD
OF TREATMENT
TENS
TENS + VS
vs
Placebo
vs
TENS
TENS + VS
Dl
D4
D7
D12
D15
D18
D21
trauma, allodynia, and sympathetic symptoms) that partial deafferentation may have been responsible for the pain. The decrease in the amplitude of sensory potentials and the failure of various therapies to relieve the pain are also in line with this possibility. On the other hand, the lack of relief obtained with anticonvulsants and the success of morphine treatment are not commonly associated with deafferentation pain [3]. How are we to explain the mechanism underlying the analgesic effects obtained in our patient as the result of vibratory and/or electrical stimulation? It has been established that large-diameter afferents are capable of modulating the pain pathways [2,4,5,19,20] and that the analgesic effects of TENS and VS are due to the fact that they activate these particular afferents [2,10,12,17,20,23]. In this context, the particularly successful analgesic effects obtained by applying combined stimulation (TENS + VS) may be attributable to the fact that with this method, a larger number of afferent fibres is stimulated than with either of the 2 single methods, so that a greater inhibition of the ‘small fibre activity’ takes place. Other mechanisms are probably involved, such as the changes in the activity of the autonomic nervous system which resulted in vasodilatation, with both TENS and VS [see in particular 1,9,14,15,26]. Lastly, the large-scale recruitment of large-diameter fibres seems to also set up an inhibitory control on the motor structures which initiate involuntary movements. The analgesic effects obtained using combined stimulation on this patient were probably not due only to deafferentation: in a previous study [7,8] on patients suffering from chronic pain and showing no signs of deafferentation, significantly greater pain relief was obtained with combined stimulation (TENS + VS) than with either VS or TENS applied separately. If the dual stimulation method turns out to be equally successful with other patients, it may be
an extremely drome.
valuable
method
of treating
this syn-
References
10
11 12
13
Abram, S.E., Asiddao, C.B. and Reynolds, A.C., Increased skin temperature during transcutaneous electrical stimulation, Anesth. Analg., 59 (1980) 22-25. Andersson, S.A., Pain control by sensory stimulation. In: J.J. Bonica, J.C. Liebeskind and D.G. Albe-Fessard (Eds.), Advances in Pain Research and Therapy, Vol. 3, Raven Press, New York, 1979, pp. 569-585. Am&, S. and Meyerson, B.A., Lack of analgesic effect of opioids on neuropathic and idiopathic forms of pain, Pain, 33 (1988) 11-23. Besson, J.M. and Chaouch, A., Peripheral and spinal mechanisms of nociception, Physiol. Rev., 67 (1987) 67-186. Boureau, F. and Willer, J.C., La Douleur, Exploration, Traitement par Neurostimulation et Electroacupuncture, Masson, Paris, 1979, 119 pp. Bovier, Ph., Hilleret, H. and Tissot, R., Traitement par le progabide dun cas de syndrome des jambes douloureuses et orteils instables, Rev. Neurol., 141 (1985) 422-424. Guieu, R., Tardy-Gervet, M.F. and Roll, J.P., Effets antalgiques des vibrations mecaniques assocites a des stimulations electriques transcutanees. In: Proc. United Kingdom and French Joint Meeting on Human Response to Vibration, I.N.R.S. Press, Vandoeuvre-les-Nancy, 1988, pp. 230239. Guieu, R., Tardy-Gervet, M.F. and Roll, J.P., Vibrations applied simultaneously with transcutaneous electrical nerve stimulation as means of treating chronic pain, Eur. J. Neurosci., Suppl. 2 (1989) 170. Kjartansson, J., Lundeberg, T. and Ktirlof, B., Transcutaneous electrical nerve stimulation (TENS) in ischemic tissue, Plast. Reconstr. Surg., 81 (1988) 813-814. Kometzny, J. and Hensel, H., Response of rapidly and slowly adaptating mechanoreceptors and vibratory sensitivity in human hairy skin, Pfltigers Arch., 368 (1977) 39-44. Lundeberg, T., Vibratory stimulation for the alleviation of chronic pain, Acta Physiol. Stand., Suppl. 523 (1983) l-51. Lundeberg, T., The pain suppressive effect of vibratory stimulation and transcutaneous electrical nerve stimulation (TENS) as compared to aspirin, Brain Res., 294 (1984) 201-209. Lundeberg, T., Long-term results of vibratory stimulation as a pain relieving measure for chronic pain, Pain, 20 (1984) 12-23.
48 14 Lundeberg, T., Naloxone does not reverse the pain-reducing effect of vibratory stimulation. Acta Anesthesiol. Stand., 29 (1985) 212-216. 15 Lundeberg, T., Abrahamsson, P., Bondesson, L. and Haker, E., Effects of vibratory stimulation on experimental and clinical pain, Scand. J. Rehab. Med., 20 (1988) 149-159. 16 Lundeberg, T., Nordemar, R. and Ottoson, D., Pain alleviation by vibratory stimulation, Pain, 20 (1984) 25-44. 17 Lundstrom, R., Responses of mechanoreceptive afferent units in the glabrous skin of the human hand to vibration, Stand. J. Work Environ. Hlth, 125 (1986) 413-416. 18 Mannheimer, J.S. and Lampe, G.N., Clinical Transcutaneous Electrical Nerve Stimulation, Davis, Philadelphia, PA, 1984, 636 pp. 19 Melzack, R. and Wall, P.D., Pain mechanism: a new theory, Science, 150 (1965) 971-979. 20 Meyerson, B.A., Electrostimulation procedures: effects, presumed rationale, and possible mechanisms. In: J.J. Bonica, J.C. Liebeskind and D.G. Albe-Fessard (Eds.), Advances in Pain Research and Therapy, Vol. 5, Raven Press, New York, 1983, pp. 495-534. 21 Montagna, P., Cirignotta, F., Sacquegna, T., Martinelli, P.. Ambrosetto, G. and Lugaresi, E., Painful legs and moving toes associated with polyneuropathy, J. Neurol. Neurosurg. Psychiat., 46 (1983) 3999403.
22 Nathan, P.W., Painful legs and moving toes: evidence of the site of the lesion, J. Neurol. Neurosurg. Psychiat., 41 (1978) 934-939. 23 Ribot-Ciscar, E., Vedel, J.P. and Roll, J.P., Vibration sensitivity of slowly and rapidly adapting cutaneous mechanoreceptors in the human foot and leg, Neurosci. Lett., 104 (1989) 130-135. 24 Schoenen, J., Gonce, M. and Delwaide, P., Painful legs and moving toes: a syndrome with different physiopathologic mechanisms, Neurology, 34 (1984) 1108-1112. 25 Schott, G.D., Painful legs and moving toes, the role of trauma, J. Neurol. Neurosurg. Psychiat., 44 (1981) 344-346. 26 Skoglung, CR., Vasodilatation in human skin induced by low-amplitude high frequency vibration, Clin. Physiol., 9 (1989) 361-372. 27 Spillane, J.D., Nathan, P.W., Kelly, R.E. and Marsden, C.D.. Painful legs and moving toes, Brain, 94 (1971) 541556. 28 Verhagen, W., Horstink, M. and Notermans, S., Painful arm and moving fingers, J. Neurol. Neurosurg. Psychiat.. 48 (1985) 384-389. 29 Wulff, C.H., Painful legs and moving toes: a report of 3 cases with neurophysiological studies, Acta Neurol. Stand.. 66 (1982) 383-287.
Pain, 42 (1990) 43-48 Elsevier PAIN 01629
Pain relief achieved by transcutaneous electrical nerve stimulation and/or vibratory stimulation in a case of painful legs and moving toes R. Guieu a, M.F. Tardy-Gervet
‘, 0. Blin b and J. Pouget
b
’ LQbwatoire de Neurobiobgie Humaine, U.R.A. C.N.R.S. 372, Centre Scientifque de St. JPrcime, MarseiNes (France), and b Clinique des Maladies du Sy.&me Nerueux, C.H. U. Timone, Marseilles (France) (Received 8 December 1989, revision received 3 March 1990, accepted 6 March 1990)
A patient is described with painful legs and moving toes. The pain had been occurring for more than 15 years, and a Summary variety of therapies had been attempted with only partial, if any, success. Only morphine had succeeded in relieving the pain, but it had to be discontinued to avoid tolerance and dependence. We devised a treatment consisting of transcutaneous electrical nerve stimulation (TENS), vibratory stimulation (VS), and a combination of the two methods (TENS f VS). TENS brought about partial pain relief, but was less effective than VS; dual stimulation (TENS + VS) led to complete alleviation of the pain. Four months later, the patient was applying dual stimulation himself at home and was thus able to maintain complete retief with 3 or 4 weekly sessions. We suggest that dual stimulation results in a large-scale recruitment of large-diameter afferent fibres and may thus set up a powerful inhibitory control of nociception in our patient. Key war&r Pam; Involuntary movements; Toes; Vibratory stimulation (VS); Transcutaneous Dual stimulation (TENS + VS)
Inaction The syndrome combining leg pain and involuntary toe movements was first described in 1971 [27]. This rare pathology has been observed in patients who have previously suffered from lumbosacral spine disease [25], lumbago and sciatica [C&22,25,29],or sustained minor lumbar spine injury [27]. Some authors have also reported the occurrence of this syndrome after peripheral nerve lesions [21] and herpes roster infection [25]. The
Correspondence to: R. Guieu, Universitt d’Aix-Marseille I, Laboratoire de Neurobiologie Humaine, U.R.A. C.N.R.S. 372, Avenue Escadrille Normandie N&men, 13397 Marseilles Cedex 13, France.
electrical nerve stimulation (TENS);
disorder can affect either one or both legs. The occurrence of a similar syndrome affecting the arms has been reported, but this is rare [28]. The pain, which usually occurs in the forefoot or the lower third of the limb is diffuse but intense, resembling causalgia. It is sometimes accompanied by paraesthesia, and in most cases the pain develops before the toe movements [25]. The pain can occur anything from a few weeks to several years after a trauma, but no obvious link is usually found between the two. It can be either alleviated or aggravated by walking or standing, whereas the toe movements can sometimes be relieved by performing active arm movements [27]. The pain does not seem to be linked to the muscle contraction, since it persists when the movements have stopped. The patients’ sleeping patterns are
0304-3959/90/$03.50 0 1990 Elsevier Science Publishers B.V. (Biomedical Division)
44
consistently disturbed by insomnia or a decrease in rapid eye movement sleep [21]. The toe movements sometimes continue at night and even increase during the REM phase [27]. Depressive reactions are frequent. Apart from those cases where the syndrome is associated with peripheral neuropathy, it sometimes involves a decrease in the amplitude of sensory potentials [27], while histological investigations have shown the existence of discrete signs suggesting segmental demyelinisation [27]. In most cases, however, the results of electrophysiological and histological studies of the nerve have been normal. The electromyographic recordings of the movements resembled those obtained during voluntary contractions and were found to involve not only the intrinsic toe muscles but also the common extensor and the toe flexor muscles. The present article reports the treatment of a particularly difficult case, using electrical and/or vibratory stimulation, which are known to be efficient means of relieving chronic pain [2,5,7,8,1113,15,16,18,20].
Case report and methods Mr. Jean D., aged 29, was admitted to hospital in April 1986 complaining of chronic intermittent pain in his right forefoot. In 1965, at the age of 6, Mr. D. was injured in a street accident and sustained cranial trauma, fractures of the pelvis and both legs, and lesion of the right sciatic nerve, mainly of the peroneal branch. At about the age of 10, he began to develop pains in the forefoot, characterised by burning sensations which gradually worsened over the months. In 1974 (age 15) the patient underwent a posterior leg tendon transplantation to compensate for defective 2nd, 3rd, and 4th right toe extensors. During the subsequent months, the symptoms increased to several attacks per week; before long, these were also accompanied by involuntary movements in the 3 middle toes. The pain was deep, seemingly in the bones, resembled burning or twisting, and became worse at night, causing intractable insomnia. Since treatment with conventional analgesics and anxiolytics was unsuccessful, a lumbar sympathetic
block was applied, which relieved the pain for several hours and the toe movements for 1 week. When this patient was admitted to hospital in April 1986, he still showed spontaneous toe movements including extension of the 2nd toe and abduction of the 3rd and 4th toes in the right foot and complained of distressing pain in the toes and forefoot extending up the antero-lateral side of the ankle. On examination, he was found to have diminished sensibility in the region of the right peroneal nerve and no Achilles tendon reflex, but no motor deficits were observed. Some cutaneous trophic changes were visible on his forefoot. In addition to continuous background pain, he suffered from several paroxysmal attacks per week which induced insomnia. The pain could be alleviated by standing, walking and consumption of alcohol, whereas coffee, changes in the weather and emotional distress were aggravating factors. Conventional analgesics and carbamazepine did not relieve the pain, whereas intravenous perfusions of clonazepam (3 mg/day) associated with amitriptyline (100 mg/day) gave temporary relief. Since the frequency of the attacks increased over the next few months and the pain was becoming more intense, treatment was undertaken with morphine derivatives. These were administered orally at first in the form of morphine sulphate (60 mg when attacks occurred), but it was soon decided to inject morphine hydrochloride (2 -3 7 mg injections per week, depending on the frequency of the attacks), alternating with corticosteroid injections. This treatment stopped both the pain and the movements, but had to be discontinued to avoid tolerance and dependency; the morphine doses were therefore gradually decreased. An external electrical stimulator delivering a lowfrequency, high-intensity current was used at this stage, along with barbiturates (secobarbital, 200 mg/day), and antidepressants (amitriptyline, 150 mg/day), which provided the patient with effective pain relief during the morphine withdrawal period, which lasted for several months. After a further 4-5 months, however, both the pain and the toe movements returned, and the patient was re-admitted to hospital in May, 1989, suffering from daily attacks. Clinical examination showed no change. The painful attacks accompa-
45
nied by toe movements took place in a context of continuous background pain. The pain arose on the dorsal surface of the 2nd, 3rd and 4th toes and extended along the forefoot and up the anterolateral side of the ankle. Despite the prescription of 30 mg of nitrazepam, the attacks always caused severe insomnia. An electromyogram showed the presence of extensive denervating lesions in the right tibialis anterior muscle. The motor conduction velocity of the tibial and peroneal nerves was normal, but the amplitude of the right sural nerve sensory potentials had decreased. No morphological abnormalities were noted in the sural nerve biopsy. Before resorting to internal stimulation of the posterior columns, it was decided to attempt to relieve the pain by means of vibratory stimulation and/or transcutaneous electrical nerve stimulation. The electrical stimulation (TENS) was applied with a stimulator delivering biphasic pulses with a duration of 0.26 msec at a frequency of 100 Hz. Four electrodes connected to 2 channels were used. One electrode was placed on the dorsal surface of the 2nd, 3rd and 4th toes, one above the instep opposite the tibial nerve, another one-third of the distance up the leg on the anterolateral side, and the last in the popliteal fossa, over the peroneal nerve. The current intensity was chosen by the patient himself, below the pain threshold. It was strong enough to produce paraesthesia and toe and ankle movements by recruiting muscular fibres the interosseus and lateral peroneal among muscles. The vibratory stimulation (VS; frequency 100 Hz, amplitude 0.5 mm), was applied by means of a prototype consisting of a motor equipped with an eccentric mass, set on a plastic base covered with a fine layer of rubber, which served as an applicator. The surface area of the applicator was 60 cm*. After several trials, the strongest analgesic effects were found to be achieved with vibrations applied to the plantar surface of the forefoot with a pressure of approximately 10 g/cm*. It is worth noting that considerable erythema occurred around the site of stimulation by the end of the session, particularly in the case of the vibratory stimulation.
Placebo treatment consisted of placing the electrical stimulation electrodes at the appropriate points simulating a TENS session, without switching on the current. Here the patient was told that he would be unable to feel anything because the current intensity was too low. Experimental procedure: seven 30 min sessions were run (see Table I): two with electrical stimulation (TENS), two with vibratory stimulation (VS), two with both electrical and vibratory stimulation (TENS + VS), and one placebo session. They were run in a pseudo-random order, and the minimum time allowed to elapse between any 2 successive sessions was 72 h. The pain levels were measured on a uisual anaiogue scale (VAS) and a &point verbal scale, consisting of: no pain, mild pain, discomforting pain, distressing pain, horrible pain, excruciating pain. The patient was requested to rate his pain on both scales before the session began, immediately after the session, and again 4, 24, 48 and 72 h after the session. The pain rating was measured on the visual scale in millimeters (from 0 to 100) and on the verbal scale in terms of the rank’ of the adjective chosen. If the patient hesitated between two adjacent adjectives, the mean rank between the two was recorded. On leaving hospital, the patient continued to apply combined stimulation (TENS + VS) himself on a regular basis.
Results The results are presented in the form of a diagram showing changes in pain intensity as a function of time. The pain intensities obtained on the visual analogue scale (Fig. 1A) were averaged between the 2 sessions run under each type of treatment (TENS, VS, TENS + VS). The placebo value corresponds to a single session. It can be seen that the analgesic effects obtained were stronger with the combined technique (TENS + VS) than with either method alone. The combined method was, moreover, the only one which resulted in complete pain relief by the end of the session (Fig. 1A). In addition, the relief was long-
46 A loo-
PLKEt33
80 -
TENS
x .C $
60-
VS
E -5 0_
40-
20 TENS N
0-
I
0
+ VS
1
40mn
1 4h
12h
24h
I
48h
72h
B
Discussion
54-
:
3-
6 .c c
2-
a” 1-
0"
The data obtained on the verbal scale were in agreement with those recorded on the visual analogue scale (Fig. 1B). This was confirmed by the satisfactory degree of correlation (Spearman rank analysis) found to exist between the two intensity ratings (R = 0.73, P -c 0.001). Four months after the patient started self-treatment at home, 3-4 sessions of combined stimulation per week sufficed to relieve his pain completely. In addition, the involuntary toe movements disappeared. He continues to use nitrazepam, 5 mg at bedtime as a hypnotic.
TENS
. VS
,
r
0
40mn
4h
12h
24h
48h
72h
Fig. 1. Changes in pain intensity assessed after each of the 3 types of treatment (TENS, VS and TENS+VS) and the placebo. The pain intensity was measured on a visual analogue scale (A) and on a 6-point verbal scale (B). The various times at which the pain was assessed are given on the abscissa. Time TO is that corresponding to the pain level before treatment. The various points on the 3 curves (TENS+VS, VS, TENS) are the means between the 2 treatment sessions. On the placebo curve, however, each point represents a single value.
lasting, since the pain returned only after 24 h on average after the treatment session, and after 48 h had developed only 40% of its previous intensity. The results obtained with the visual analogue scale were processed statistically. The results of the Wilcoxon test showed that the combined method was significantly more effective than either VS (P = 0.001) or TENS (P = 0.001) alone. On the other hand, VS had significantly stronger analgesic effects than TENS (P = 0.004). All 3 therapeutic methods had significantly stronger effects than the placebo (P < 0.02).
Our patient presented with a classical case of what has been called the ‘painful legs and moving toes’ syndrome [21,22,24,25,27,29]; he was as difficult to treat as those patients described by other authors [6,21,22,24,25,27,29]. The excellent results of the combined stimulation, which resulted in total and long-lasting pain alleviation and abolished the toe movements, is certainly worth noting. The physiopathology of this syndrome has given rise to much debate as to the origin of the pain and the toe movements. Nathan et al. [22] believe them to be due to the activation of afferent fibres in the posterior nerve roots, which triggers signals to interneuronal circuits and to motoneurones. The exact relationship between the pain and the toe movements is difficult to establish, however, since the former can occur in the absence of the latter. Spillane et al. [27] have suggested that the pain may be caused by impairment of the sympathetic nervous system. It is difficult to explain, however, why sympathectomy has failed to relieve the pain, whereas blocking the sympathetic ganglia by local ganglionic injections of anaesthetic or phenol has led to remittance of the symptoms for several hours [27, the present case]. Some authors have hypothesised central and others peripheral mechanisms. According to Schoenen et al. [24]: ‘Painful legs and moving toes are not a homogenous entity, but a syndrome of diverse causes.’ In the case of our patient, there was certainly some clinical evidence (a case history involving
47
TABLE ORDER
I OF SESSIONS
DURING
THE 21 DAY PERIOD
OF TREATMENT
TENS
TENS + VS
vs
Placebo
vs
TENS
TENS + VS
Dl
D4
D7
D12
D15
D18
D21
trauma, allodynia, and sympathetic symptoms) that partial deafferentation may have been responsible for the pain. The decrease in the amplitude of sensory potentials and the failure of various therapies to relieve the pain are also in line with this possibility. On the other hand, the lack of relief obtained with anticonvulsants and the success of morphine treatment are not commonly associated with deafferentation pain [3]. How are we to explain the mechanism underlying the analgesic effects obtained in our patient as the result of vibratory and/or electrical stimulation? It has been established that large-diameter afferents are capable of modulating the pain pathways [2,4,5,19,20] and that the analgesic effects of TENS and VS are due to the fact that they activate these particular afferents [2,10,12,17,20,23]. In this context, the particularly successful analgesic effects obtained by applying combined stimulation (TENS + VS) may be attributable to the fact that with this method, a larger number of afferent fibres is stimulated than with either of the 2 single methods, so that a greater inhibition of the ‘small fibre activity’ takes place. Other mechanisms are probably involved, such as the changes in the activity of the autonomic nervous system which resulted in vasodilatation, with both TENS and VS [see in particular 1,9,14,15,26]. Lastly, the large-scale recruitment of large-diameter fibres seems to also set up an inhibitory control on the motor structures which initiate involuntary movements. The analgesic effects obtained using combined stimulation on this patient were probably not due only to deafferentation: in a previous study [7,8] on patients suffering from chronic pain and showing no signs of deafferentation, significantly greater pain relief was obtained with combined stimulation (TENS + VS) than with either VS or TENS applied separately. If the dual stimulation method turns out to be equally successful with other patients, it may be
an extremely drome.
valuable
method
of treating
this syn-
References
10
11 12
13
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