Pain relief achieved by transcutaneous electrical nerve stimulation and/or vibratory stimulation in a case of painful legs and moving toes

Transcutaneous electrical nerve stimulation in the management of restless legs syndrome symptoms: A single-blind, parallel-group clinical study

The aim of this study was to investigate the additional effect of transcutaneous electrical nerve stimulation (TENS) on the control of the symptoms of restless legs syndrome (RLS). A total of 46 randomly selected patients diagnosed with RLS were divided into two groups in a single-blind study to either receive pramipexole (0.25 mg daily) plus 10 sessions of TENS or only pramipexole (0.25 mg daily) for 4 weeks. The severity of the symptoms was determined according to the International Restless Legs Syndrome Rating Scale (IRLSRS) and the Pittsburgh sleep quality index (PSQI) at the beginning of the treatment, post-treatment, and at an 8 week follow-up. A significant time interaction was observed between the groups for all measurement outcomes, revealing differences in favour of the experimental group's IRLSRS and PSQI scores. A notable improvement was also observed in the IRLSRS and PSQI scores in both groups at the end of treatment and during the 8 week follow-up period. In comparison with pramipexole monotherapy, the results of this study showed that the use of TENS therapy combined with a low dose of pramipexole (0.25 mg daily) is therapeutically beneficial in the treatment of RLS over an 8 week follow-up period.

Music and low-frequency vibrations for the treatment of chronic musculoskeletal pain in elderly: A pilot study

BACKGROUND

Transcutaneous vagal nerve stimulation has analgesic potential and might be elicited by abdominally administered low-frequency vibrations. The objective was to study the safety and effect of a combination of music and abdominally administered low-frequency vibrations on pain intensity in elderly patients with chronic musculoskeletal pain.

METHODS

This trial was an international multicenter, randomized controlled pilot study. Patients at age ≥ 65 years with musculoskeletal pain for ≥ 3 months and a daily pain score ≥ 4 out of 10 were recruited at three centers. They were randomized to receive either a combination of music and low-frequency (20-100 Hz) vibrations administered to the abdomen, or a combination with the same music but with higher frequency (200-300 Hz) vibrations administered to the abdomen. Low-frequency vibrations were expected to result in pain reduction measured with a numeric pain rating scale (NRS). Patients in both groups received eight treatments of the music combined with the vibrations in three weeks. Primary outcomes were safety (Serious Adverse Events) and pain intensity measured at baseline, after the last treatment and at six weeks follow-up. Multilevel linear model analyses were performed to study group and time effects.

RESULTS

A total of 45 patients were analyzed according to intention-to-treat principle. After 344 treatments, 1 Adverse Event was found related to the intervention, while 13 Adverse Events were possibly related. A multilevel linear model showed that the interaction effect of group by time did not predict pain intensity (F[1, 45.93] = 0.002, p = 0.97) when comparing pain intensity at baseline, after the last treatment and at follow-up.

CONCLUSIONS

The combination of music and abdominally administered vibrations was found to be safe and well tolerated by the elderly patients. However, over time, neither the low-frequency treatment group nor the high-frequency treatment group provided clinically meaningful pain relief. There is no evidence that the low-frequency treatment elicited vagal nerve stimulation.

TRIAL REGISTRATION

The trial was prospectively registered in the Netherlands Trial Register (NTR: NL7606) on 21-03-2019.

The effects of peripheral tactile stimulation on memory in patients with probable Alzheimer's disease

The authors investigated whether peripheral tactile nerve stimulation might improve memory in patients with iProbable Alzheimer s disease. The hypothesis was derived from animal studies in which peripheral stimulation resulted in activation of septo-hippocampal neurons. Our data meveal that tactile stimulation improved visual short-term, visual long-!erm, and verbal long-term mem orv in Alzheimer patients. In addition, an enhancement in verbal fluency was demonstrated. After a period of six weeks without stimulation, nio noticeable effects remained.

Effects of Transcutaneous Electrical Nerve Stimulation (TENS) on Self-Efficacy and Mood in Elderly with Mild Cognitive Impairment

In previous studies, transcutaneous electrical nerve stimulation (TENS) has been applied to patients with either Alzheimer’s disease (AD) or incipient dementia, resulting in an enhancement in memory and verbal fluency. Moreover, affective behavior was shown to improve. Based on the positive effects of TENS in AD, it was hypothesized that TENS would improve self-efficacy in nondemented elderly with mild cognitive impairment (MCI) who live in a residential home. Four outcome measures, that is, a Dutch translation of the General Self-Efficacy Scale (Algemene Competentie Schaal), the Groninger Activity Restriction Scale, the Philadelphia Geriatric Center Morale Scale, and the Geriatric Depression Scale, were administered. Overall, the results suggest that the experimental group showed a mild improvement in self-efficacy and mood. In contrast, the placebo group showed a considerable reduction in self-efficacy and an increase in depression. Limitations of the present study and suggestions for future research are discussed.

Spinal-generated movement disorders: a clinical review

Spinal-generated movement disorders (SGMDs) include spinal segmental myoclonus, propriospinal myoclonus, orthostatic tremor, secondary paroxysmal dyskinesias, stiff person syndrome and its variants, movements in brain death, and painful legs-moving toes syndrome. In this paper, we review the relevant anatomy and physiology of SGMDs, characterize and demonstrate their clinical features, and present a practical approach to the diagnosis and management of these unusual disorders.

Medical devices for restless legs syndrome - clinical utility of the Relaxis pad

Restless Legs Syndrome or Willis–Ekbom Disease, a neurosensory disorder, can be treated with pharmaceuticals or conservatively. This review focuses on conservative treatments, more specifically on treatments with medical devices. Two modes of action, enhancement of circulation and counter stimulation, are introduced. Medical devices that use enhancement of circulation as their mechanism of action are whole body vibration, pneumatic compression, and near-infrared light. Medical devices that use counter stimulation include transcutaneous electrical nerve stimulation and the vibration Relaxis pad. The clinical utility of the Relaxis pad and its place in therapy is proposed.

Functional impact of vibratory proprioceptive assistance in patients with facioscapulohumeral muscular dystrophy

INTRODUCTION

In this study we analyzed the effects of a rehabilitation method based on the use of vibratory proprioceptive assistance (VPA) in subjects with facioscapulohumeral muscular dystrophy.

METHODS

Eight subjects were given 1 month of mechanical vibratory treatment that consisted of 8 sessions of 40-min stimulation on the more affected side. During each session, illusory movements were induced as follows: sensations of extension or flexion of the forearm or elevation of the arm via vibration applied to the distal tendon of the biceps brachialis (BB), triceps brachialis (TB), or pectoralis major muscles (PM), respectively, and of elevation of the arm with extension or flexion of the forearm via vibration of PM+BB or PM+TB, respectively.

RESULTS

Treatment led to a significant increase in the amplitude of voluntary shoulder flexion, constant score, and self-rated health.

CONCLUSION

VPA may serve as a rehabilitation method for reducing the deleterious effects of decline in motor activities.

Kinesthetic illusions attenuate experimental muscle pain, as do muscle and cutaneous stimulation

In the present study, muscle pain was induced experimentally in healthy subjects by administrating hypertonic saline injections into the tibialis anterior (TA) muscle. We first aimed at comparing the analgesic effects of mechanical vibration applied to either cutaneous or muscle receptors of the TA or to both types simultaneously. Secondly, pain alleviation was compared in subjects in whom muscle tendon vibration evoked kinesthetic illusions of the ankle joint. Muscle tendon vibration, which primarily activated muscle receptors, reduced pain intensity by 30% (p<0.01). In addition, tangential skin vibration reduced pain intensity by 33% (p<0.01), primarily by activating cutaneous receptors. Concurrently stimulating both sensory channels induced stronger analgesic effects (-51%, p<0.01), as shown by the lower levels of electrodermal activity. The strongest analgesic effects of the vibration-induced muscle inputs occurred when illusory movements were perceived (-38%, p=0.01). The results suggest that both cutaneous and muscle sensory feedback reduce muscle pain, most likely via segmental and supraspinal processes. Further clinical trials are needed to investigate these new methods of muscle pain relief.

Spinal stimulation for movement disorders

Epidural spinal cord stimulation (SCS) is currently proposed to treat intractable neuropathic pain. Since the 1970s, isolated cases and small cohorts of patients suffering from dystonia, tremor, painful leg and moving toes (PLMT), or Parkinson’s disease were also treated with SCS in the context of exploratory clinical studies. Despite the safety profile of SCS observed in these various types of movement disorders, the degree of improvement of abnormal movements following SCS has been heterogeneous among patients and across centers in open-label trials, stressing the need for larger, randomized, double-blind studies. This article provides a comprehensive review of both experimental and clinical studies of SCS application in movement disorders.

Painful legs and moving toes

The syndrome of painful legs-moving toes (PLMT) is an adult-onset, rare disorder characterized by pain, typically of a neuropathic quality, in the feet or legs, associated with writhing movements of one or more toes. It is the pain which usually brings the patient to medical attention. The syndrome may be unilateral or bilateral. Identical toe movements may occur without pain, referred to as: "painless legs-moving toes," and a similar condition affects the upper limbs: "painful arms-moving fingers." The pathophysiology of PLMT and its variants is not known but most reports suggest an association with a peripheral lesion, usually at the level of the root or nerve, though in many cases no cause is found. It has been suggested that a peripheral lesion causes aberrant input leading to "central reorganization," probably at the level of the spinal cord, and that the latter is responsible for the pain and movement. Treatment is often unsatisfactory and many drugs commonly used for neuropathic pain have been reported anecdotally to help (e.g., gabapentin). Other anecdotal therapies include spinal blocks, spinal cord stimulation, and local injection of botulinum toxin.

Case reports: Painful limbs/moving extremities: report of two cases

BACKGROUND

Painful limbs/moving extremities is a relatively rare condition characterized by aching pain in one limb and involuntary movement in the affected fingers or toes. Its pathomechanism is unknown. We report two patients with painful limbs/moving extremities. In one patient with a painful arm and moving fingers, the symptoms were resolved after surgery.

CASE DESCRIPTIONS

Patient 1 was a 36-year-old man with a painful arm and moving fingers. Treatment with administration of analgesics was not effective. Postmyelographic CT showed stenosis of the right C5/C6 foramen attributable to cervical spondylosis and a defect of the contrast material at the foramen. He was treated with cervical foraminotomy. Patient 2 was a 26-year-old woman with a painful leg and moving toes. The pain and involuntary movement appeared 2 weeks after discectomy at L5/S1. Lumbar MRI and myelography showed no indications of nerve root compression. She was treated with a lumbar nerve root block. The pain and involuntary movement completely disappeared in both patients after treatment.

LITERATURE REVIEW

Numerous studies report treatments for painful limbs/moving extremities, but few report successful treatment. Recently, botulinum toxin A injection and epidural spinal cord stimulation have been used and are thought to benefit this condition. Successful surgical treatment previously was reported for only one patient.

PURPOSES AND CLINICAL RELEVANCE

If imaging indicates compression of nerve tissue, we believe surgical decompression should be considered for patients with painful limbs/moving extremities who do not respond to nonoperative treatment.

The efficacy of mechanical vibration analgesia for relief of heel stick pain in neonates: a novel approach

BACKGROUND

Hospitalized infants are often exposed to many painful procedures as a result of their illness or disease process. Untreated or poorly treated pain can have deleterious effects on normal nociceptive pain development as well as future development of pain pathways. Mechanical vibration has been found to be efficacious in adult and pediatric populations for the relief of mild-to-moderate acute and chronic pain. However, little is known about the efficacy of this intervention in the neonatal population.

AIM

The purpose of this study was to test the hypothesis that mechanical vibration would be efficacious in the relief of pain associated with heel sticks in neonates. Heel sticks are one of the most common painful procedures during neonatal hospitalization.

STUDY DESIGN

A random-sequencing crossover design was used with infants acting as their own controls.

SUBJECTS

Newborn infants of 35 weeks' gestation or greater (N = 20) met the inclusion criteria for the study.

OUTCOME MEASURES

Pain during heel stick was measured with the Neonatal Infant Pain Scale. The Neonatal Infant Pain Scale is a nonintrusive tool with extensive evidence of its reliability and validity in the neonatal population, when used by trained observers.

RESULTS

Mechanical vibration produced an analgesic effect for infants who had previously experienced painful heel sticks that approached statistical significance.

CONCLUSIONS

The apparent limitations of mechanical vibration as analgesia may be due to the concurrent use of sucrose and pacifier, the effects of order (ie, habituation), or type II error. Because vibration produced the predicted positive effect in some circumstances, further investigation in larger samples within a randomized clinical trial is warranted.

Painful limbs/moving extremities

Painful limbs/moving extremities (PLME) is a disorder characterized by spontaneous, complex, slow (1-2 Hz) involuntary toe or finger movements. The movements that can be bilateral or unilateral are usually accompanied by pain in the affected limbs. Painless variants are less common. PLME has been associated with peripheral and central nervous system disease although idiopathic cases have been reported. Its etiopathogenesis is unknown and treatment approaches remain largely empirical. Nerve blocks and botulinum toxin type A injections as well as oral medication have had some measure of success. Current theories suggest that central oscillator(s) at the spinal or supraspinal levels may be involved. Future research in PLME should include prospective electrophysiological and functional imaging studies as well as clinical trials with botulinum toxin injections and oral pharmacological agents.

Proprioceptive feedback enhancement induced by vibratory stimulation in complex regional pain syndrome type I: An open comparative pilot study in 11 patients

OBJECTIVE

Complex regional pain syndrome type I (CRPS-I) is now considered as a central nervous system disease with peripheral manifestations. CRPS-I may result from a mismatch between sensory input and motor output leading to a disorganization of motor programming in cortical structures. According to previous studies in the field of motor control, one efficient way to correct this mismatch could be a proprioceptive feedback enhancement. The goal of the present study was to determine whether vibratory stimulation by improving proprioceptive feedback may increase range of motion and minimize pain in patients with CRPS-I.

METHODS

An open non-randomized study was conducted in 11 patients with CRPS-I of the hand and wrist. Conventional rehabilitation sessions were given for 10 weeks. During each session, patients in the intervention group (n=7) received vibratory stimulation of the affected region; the remaining 4 patients served as the controls.

RESULTS

After 10 weeks, range-of-motion gains were about 30% larger and pain severity was about 50% lower in the intervention group than in the control group. A significant decrease in analgesic use occurred in the intervention group.

DISCUSSION

Vibratory stimulation may significantly improve range of motion and pain in patients with CRPS-I, probably by reestablishing consonance between sensory input and motor output at cortical level. Prospective randomized studies in larger numbers of patients are needed. Cross-over designs or simulated vibratory stimulation should be used to minimize bias.

[Painful legs and moving toes syndrome]

Painful legs and moving toes syndrome is a rare medical picture characterized by involuntary movements of the toes or the whole foot and pain in lower limbs. However, this must be kept in mind due to its association with other diseases and its possibility of being the first symptom. Spinal cord and cauda equina diseases, neuropathies, radiculopathies, drugs and other systemic diseases are the main cause of this syndrome although many cases are still idiopathic. Its diagnosis is essentially clinical and its treatment is complex, including different combinations of drugs and invasive techniques, and generally with a bad response.

Sympathetic nervous system involvement in the syndrome of painful legs and moving toes

The objective of this study is to investigate sympathetic nervous system involvement in 2 patients with painful legs and moving toes. The first case was studied several years after the initiating trauma produced a peripheral nerve lesion and demonstrated the characteristic sequence of progression of pain and moving toes from the injured leg to the contralateral leg. The second case was initially studied within 3 months of an injury that did not produce definitive signs of a peripheral nerve lesion. Pain increased when the patients were startled and subsided temporarily after sympathetic blockade. In the first patient, toe movements and allodynia to light tactile stimulation persisted during sympathetic blockade, and pain sometimes returned before the vascular effects of blockade disappeared. In the second patient, pain and toe movements could be provoked reproducibly by light tactile stimulation of the affected foot and by sympathetic arousal. These symptoms and signs disappeared after lumbar sympathectomy, and re-emerged when signs of sympathetic reinnervation were detected. We concluded that sympathetic neuronal discharge may provoke pain by activating an impulse generator in the affected limb. Sympathetic involvement in the painful legs and moving toes syndrome appeared to be greater in the second case than the first, presumably due to differences in the initial injury or stage of the condition.

Epidural spinal cord stimulation for the treatment of painful legs and moving toes syndrome

A case of 51-year-old male with painful legs and moving toes syndrome was successfully treated with epidural spinal cord stimulation. He was previously treated with varieties of medication, epidural block, transcutaneous nerve stimulation, lumbar sympathetic block, with no or only a transient effect. Epidural spinal cord stimulation was applied by means of percutaneously inserted epidural electrodes connected to a percutaneous extension for 2-week test stimulation period and later to a permanent device (ITREL). Pain and involuntary movement were relieved almost completely during the stimulation and the effect was still evident 6 months later.

Syndrome of painful legs and moving toes: a case study

Painful legs and moving toes syndrome is characterized by spontaneous causalgic pain in the lower extremities associated with peculiar involuntary movements of the lower extremities, especially the toes and feet. The pain is diffuse, intractable, aching, and deep. The movements consist of persistent writhing movements in the digits that cannot be limited voluntarily. The syndrome has been observed after a variety of abnormalities affecting the posterior nerve roots, the spinal ganglia, and the peripheral nerves. This article reviews commonly reported findings and current concepts in the etiology and management of this condition.

Effects of "isolated" transcutaneous electrical nerve stimulation on memory and affective behavior in patients with probable Alzheimer's disease

BACKGROUND

In previous studies, transcutaneous electrical nerve stimulation (TENS), tactile stimulation, and a combination of the two resulted in cognitive and affective improvements in patients with Alzheimer's disease (AD). As in those studies the therapist was present during the treatment of the experimental and control group (sham stimulation), a positive effect of the combination of TENS with interpersonal communication could not be excluded. Therefore, the effects of "isolated" TENS, i.e., in the absence of the therapist, on memory and affective disturbances in AD patients were examined.

METHODS

Eighteen subjects (78-92 years old) met the NINCDS-ADRDA criteria for the clinical diagnosis of probable AD. To evaluate treatment effects, the experimental group (9) and the control group (9) underwent a number of neuropsychological tests and two observation scales.

RESULTS

Treatment effects were observed for nonverbal short-term (Visual Memory) and long-term (Face Recognition) memory, word fluency (Verbal Fluency), and need of help, whereas patients' affective behavior did not improve.

CONCLUSIONS

The results of the present study show that isolated TENS has a positive effect on patients' cognitive and independent functioning; however, isolated TENS appeared not to have a therapeutic effect on patients' affective behavior.

Combined neuromuscular electrical stimulation and transcutaneous electrical nerve stimulation for treatment of chronic back pain: a double-blind, repeated measures comparison

OBJECTIVES

A preliminary examination of NMES and combined NMES/TENS for the management of chronic back pain.

DESIGN

Double-blind, placebo-controlled, randomized repeated measures.

SUBJECTS AND SETTING

Consecutive sample of 24 chronic back pain patients (16 women and 8 men) attending an outpatient pain clinic (mean age 51.67 years, mean pain duration 3.83 years). All treatments were administered at home.

INTERVENTIONS

Subjects self-administered NMES, combined NMES/TENS, TENS, and placebo treatments. Each treatment had a duration of 5 consecutive hours per day over 2 consecutive days, with a 2-day hiatus between treatments to minimize carryover effects.

MAIN OUTCOME MEASURES

Pain reduction was assessed through pretreatment to posttreatment differences on the Present Pain Intensity (PPI) scale, and a visual analogue scale of Pain Intensity (VAS-I). Posttreatment pain relief was assessed using a visual analogue scale of Pain Relief (VAS-R).

RESULTS

Combined treatment, NMES, and TENS each produced significant pretreatment to posttreatment reductions in pain intensity as measured by both the PPI and VAS-I (p < .05). Combined treatment was superior to placebo on pain reduction (p = .001, p = .016) as well as pain relief (p < .001). Combined treatment was also superior to both TENS and NMES for pain reduction and pain relief (p < .01). NMES and TENS were superior only to placebo for pain relief (p < .001).

CONCLUSIONS

Combined NMES/TENS treatment consistently produced greater pain reduction and pain relief than placebo, TENS, or NMES. NMES alone, although less effective, did produce as much pain relief as TENS. Although preliminary, this pattern of results suggests that combined NMES/TENS may be a valuable adjunct in the management of chronic back pain. Further research investigating the effectiveness of both NMES and combined NMES/TENS seems warranted.

Adenosine and neuropathic pain

Recent studies have reported the possibilities of relieving neuropathic pain by administering adenosine or its analogs. In order to determine if there exists a metabolic anomaly of this nucleoside in patients with neuropathic pain, circulating adenosine levels were compared in three patient groups. The first was composed of individuals suffering from neuropathic pain, the second of patients with nervous system lesions in the absence of pain, and the third was composed of patients suffering from pain resulting from excessive nociception. The adenosine blood levels of these patients were compared to those of a control group. Finally, adenosine in the cerebrospinal fluid (CSF) of some patients was also assayed. The results show that there are reduced levels of blood and CSF adenosine in patients with neuropathic pain. This adenosine deficiency could explain the potential therapeutic effects of administering adenosine or its analogs.

Painful legs and moving toes associates with tarsal tunnel syndrome and accessory soleus muscle

Painful legs, moving toes is a rare syndrome characterized by leg pain and uncontrolled toe movements. We present a 35-year-old man with a 1-year history of unilateral knee, calf, and medial ankle pain with spontaneous movements of second through fifth toes. Electrodiagnostic studies showed an absent lateral plantar nerve response consistent with a tarsal tunnel entrapment neuropathy. Cine magnetic resonance imaging revealed a large accessory soleus muscle compressing the flexor hallucis longus in the tarsal tunnel of the affected extremity. Lidocaine block of the tibial nerve at the popliteal fossa did not stop these movements, but blockade of the medial and lateral plantar nerves distal to the medial malleolus stopped them temporarily. Treatment with foot orthotics and cessation of running activity decreased the symptoms. We conclude that painful leg and moving toes in this patient resulted from a compression neuropathy at the tarsal tunnel possibly caused by a large adjacent accessory soleus muscle.

Effects of short-term transcutaneous electrical nerve stimulation on memory and affective behaviour in patients with probable Alzheimer's disease

The present study investigated whether a 30-minute-a-day transcutaneous electrical nerve stimulation (short-term TENS) might improve disturbances in memory and affective behaviour in patients with probable Alzheimer's disease. The hypothesis was derived from former studies in which beneficial effects on memory and affective behaviour of Alzheimer patients were found after a daily application of 6-h TENS and a 30-min tactile stimulation. The present data reveal that short-term TENS improved some aspects of verbal and visual short-term and long-term memory. Moreover, patients who had undergone this treatment felt, e.g., less dejected, less gloomy, less irritable, more cheerful, more active, and more alert. They were also more interested in social contacts and participated more in daily activities. After a period of 6 weeks following treatment, the effects on memory as well as the improvements in affective behaviour partially remained.

Improvement of left visuo-spatial hemineglect by left-sided transcutaneous electrical stimulation

The effects of transcutaneous electrical stimulation on left visuo-spatial hemineglect, assessed by a visuo-motor exploratory task (letter cancellation), were investigated in patients with right hemisphere lesions. In Experiment 1 left neck stimulation temporarily improved the deficit in 13 out of 14 patients (93%), while stimulation of the right neck had no positive effects, worsening exploratory performance in nine patients (64%). Experiment 2 showed that left neck stimulation temporarily improved neglect also when head movements were prevented by a chin-rest. In Experiment 3, stimulation of both the left hand and left neck had comparable positive effects on visuo-spatial hemineglect. These results are interpreted in terms of: (1) non-specific activation of the right hemisphere, contralateral to the stimulation side; (2) specific directional effects of left somatosensory stimulation on the egocentric co-ordinates of extra-personal space, which in neglect patients are distorted towards the side of the brain lesion.

AAEM minimonograph #44: diseases associated with excess motor unit activity

Stiff-man syndrome is due to hyperexcitability of anterior horn cells, possibly related to interference with the synthesis or action of gamma-aminobutyric acid. Unexpected acoustic and exteroceptive stimuli produce exaggerated muscle responses. Needle electrode examination of involved muscles yields nonspecific findings and demonstrates involuntary motor unit activity. The appearance and firing pattern of motor units are normal except that agonist and antagonist muscles may contract concurrently. Continuous muscle fiber activity (Isaacs' syndrome) comprises a heterogeneous group of hereditary and acquired disorders that cause hyperexcitability of peripheral nerves. Some are associated with electrophysiologic evidence of peripheral neuropathy and some are not. Repetitive afterdischarges often follow the M-, H-, and F-waves. Needle electrode examination reveals an abnormal pattern of motor unit firing, consisting of myokymic discharges, doublets and multiplets, neuromyotonic discharges, and fasciculations. These abnormalities may occur alone or in combination.

Use of HPLC to measure circulating adenosine levels in migrainous patients

Adenosine is a powerful natural vasodilator that could be involved in migraine. It is difficult to assay this nucleoside, however, because it has a short half-life. We have used HPLC to compare the concentrations of blood adenosine sampled in crisis-free intervals and during crisis periods in ten patients with common migraine and have compared these levels to those noted in a control population. Our sampling technique uses vacuum suction and enables rapid mixing of the blocking solution and whole venous blood. This results in reproducible HPLC assays. We also show that, during a migraine crisis, mean blood adenosine levels increase by 47%. However, the origin of this adenosine release is difficult to define.

Substance P-like immunoreactivity and analgesic effects of vibratory stimulation on patients suffering from chronic pain

By applying vibratory stimulation to patients suffering from pain, it is possible to set up an inhibitory control on the pain pathways which is based on the activation of large-sized afferent fibres. The exact mechanisms responsible for these analgesic effects still remain to be determined, however. For this purpose, we investigated in the present study whether or not the analgesic effects were accompanied by a decrease in the CSF substance P-like immunoreactivity levels (SPLI) of seven patients suffering from chronic pain, who were fitted with a ventriculo-peritoneal drain. The SPLI levels were determined before and after 30-min vibratory stimulation sessions. The results show that the SPLI levels decreased as the result of the vibration, but this decrease seems to be too slight to account for the pain relief obtained.

Met-enkephalin and beta-endorphin are not involved in the analgesic action of transcutaneous vibratory stimulation

Although the analgesic effects observed during the application of vibration may be attributable to neuronal inhibition of the pain pathways, this does not account for the fact that pain relief sometimes persists for a long time after the end of vibration treatment. Two experiments were carried out in order to determine whether pain relief might involve the release of endogenous opioids. In the first experiment, we studied the effects of injecting either a morphine antagonist, naloxone (0.4 mg), or a placebo, on the analgesia resulting from vibratory stimulation in 12 patients suffering from acute or chronic pain. In the second experiment, the Met-enkephalin and beta-endorphin levels were determined before and after 30 min vibratory stimulation in the cerebrospinal fluid of 8 patients suffering from chronic pain and 1 control subject, all of whom had been fitted with a ventriculo-peritoneal drain which made it possible to collect samples of cerebrospinal fluid painlessly. The results of these experiments show, on the one hand, that the effects of naloxone on the vibration-induced analgesia did not differ from those of the placebo and, on the other hand, that no increase in the Met-enkephalin or beta-endorphin levels occurred concomitantly with pain relief. It will therefore be necessary to investigate other mechanisms as possible means of explaining the post-vibratory analgesic effects.

Analgesic effects of vibration and transcutaneous electrical nerve stimulation applied separately and simultaneously to patients with chronic pain

The analgesic effects of transcutaneous electrical nerve stimulation (TENS) and vibratory stimulation (VS), used both separately and simultaneously, were compared in 24 patients suffering from chronic pain. We tested the hypothesis that these combined procedures might improve the pain reducing effects obtained with a single type of stimulation, since they make it possible to recruit a larger number of large diameter afferents and/or to increase the discharge frequencies. Four 35-minute treatment sessions (VS, TENS, VS + TENS, Sham stimulation) were run with each patient. The vibrations (100 Hz) and TENS (100 Hz) were applied to the surface of the painful region. The sham stimulation treatment consisted of positioning the TENS electrodes without actually delivering any current. The short form of the McGill pain questionnaire was used to assess the subjects' pain levels. The assessments took place immediately after any treatment (0h.), and again 4 hours and 24 hours later. The results showed that dual stimulation not only alleviated pain in more cases than either VS or TENS alone, but also had stronger and more long-lasting analgesic effects. On the other hand, all three types of stimulation used produced stronger analgesic effects than those obtained with the sham stimulation.