Transcutaneous Neurostimulation Research Articles

Transversus Abdominis Plane Block in the Treatment of Chronic Postsurgical Abdominal Wall Pain Improves Patient Quality of Life: A Retrospective Study and Literature Review

BACKGROUND: Although poorly studied, chronic postsurgical neuropathic pain (CPNP) represents the second most frequent chronic neuropathic pain etiology, probably affecting 0.5% to 75% of patients with a severe impact on quality of life (QoL). No consensus or treatment algorithm has been elaborated to date, despite a large variety of approaches now available. Transversus abdominis plane (TAP) block has been endorsed as an efficient treatment for acute postoperative pain although its effect on CPNP in terms of intensity and QoL has yet to be considered. OBJECTIVES: The main aim of this study was to evaluate the efficacy of TAP blocks in terms of QoL on patients suffering from abdominal CPNP, including a socio-economic analysis. Results were compared with those published in the recent literature. STUDY DESIGN: Retrospective, monocentric, observational clinical study. SETTING: This single-center retrospective study was conducted at the Chronic Pain Center, Department of Anesthesia, Robert Debré University Hospital, Reims, France. METHODS: From January 2018 through April 2021, all patients suffering from abdominal CPNP treated with a TAP block were enrolled. QoL was assessed using the SF-12 survey. Socio-economic and demographic data were also collected. A literature review was performed using appropriate Medical Subject Headings (MeSH) terms. RESULTS: A TAP block was administered to 44 consecutive patients suffering from CPNP. After a mean follow-up of 11.8 weeks, 86.7% of the patients reported significant effectiveness of the treatment, including an improvement in QoL (P < 0.001), pain scale ratings (P < 0.001) and analgesic requirement (P < 0.001). In term of socio-economic results, one-fifth of the patients returned to work after treatment. The literature review yielded 60 research studies, only 2 of which met our inclusion criteria. These retrospective studies indicated a 76.5% and 81.9% efficacy rate after 12 and 15.5 weeks, respectively. LIMITATIONS: This was a retrospective study with a small sample size. Further investigation should include medical and economic parameters as well as a comparison of TAP block with second-line drug therapies such as transcutaneous neurostimulation, and capsaicin and lidocaine patches. Other anesthetic molecules such as onobotulinumtoxin A (botulinum toxin) combined with steroids should be assessed for these patients. CONCLUSION: The TAP block is easy to learn, easy to reproduce, and easy to administer. After pooling our results with those from the literature, a TAP block is deemed to be effective for the treatment of CPNP with 82.25% effectiveness over a mean time of 13.9 weeks. A TAP block improves long-term QoL, reduces consumption of painkillers and lowers pain scale scores. Thus, it may reduce health care costs. We argue that A TAP block should be considered early, from the onset of the first pain symptoms. KEY WORDS: Anesthetics therapeutic use, hernia, inguinal surgery, abdominal muscles innervation, nerve block methods, anesthesia, conduction methods, postoperative treatment, wounds and injuries, drug therapy

Pain Relief With Peripheral Nerve Stimulation of Superficial Cervical Plexus: A Case Report and Literature Review

BACKGROUND: Neuropathic head and facial pain are relatively common and difficult to treat pain syndromes encountered in pain clinics throughout the world. Atypical syndromes with overlapping nerve distributions can be particularly frustrating for patients and providers. In recent years, as providers search for alternatives to medications, advances in neuromodulation technology, including spinal cord stimulation and peripheral nerve stimulation (PNS), have shown promise in treating neuropathic pain confined to specific nerve distributions, such as the greater and lesser occipital nerves. However, there is limited literature describing the use of PNS for atypical facial pain. We report the first known case of PNS to the superficial cervical plexus in a 45-year-old woman with bilateral ear and postauricular pain. CASE REPORT: A 45-year-old woman presented with over 6 years of bilateral ear and periauricular pain in the auriculotemporal and lesser occipital nerve distribution. Conservative management, including neuropathic pain agents, ketamine infusions, nasal sprays, opioids, nonsteroidal anti-inflammatory medications, ice, heat, and transcutaneous neurostimulation, provided limited relief. She had excellent pain control with a series of nerve blocks to the superficial cervical plexus; however, relief was short term. In an attempt for a more long-term solution, she underwent implantation of the SPRINT PNS (MicroLead, SPR Therapeutics, Cleveland, OH), which resulted in 100% pain relief, improved function at work, and improved sleep tolerance throughout the 60-day treatment. Unfortunately, her symptoms returned shortly after treatment course completion. CONCLUSIONS: To our knowledge, this is the first case utilizing PNS of the superficial cervical plexus to treat atypical facial pain. The 60-day trial resulted in 100% pain relief of previously debilitating and functionally limiting pain symptoms during the treatment phase suggesting that the superficial cervical plexus may be a reasonable target for permanent PNS implants. KEY WORDS: Peripheral nerve stimulator, peripheral nerve stimulation, superficial cervical plexus, atypical facial pain, anesthetic blockade, pain relief, neuropathic pain, neuromodulation, SPRINT

Using of transcutaneous supraorbital nerve stimulation in the treatment of chronic tension type headache

BACKGROUND. The clinical study was carried out as part of the scientific work Non-drug treatment methods and optimization of coping strategies for chronic tension type headache.
 AIM. To evaluate the effectiveness of the use of transcutaneous neurostimulation of the supratrochlear and supraorbital nerves in patients with chronic tension type headache.
 MATERIAL AND METHODS. The clinical study was conducted from February to August 2021. In total, 50 patients with chronic tension type headache took part in the study, which were divided into two groups: the main group (40 participants) and the control group (10 participants). In the main group, patients received transcutaneous neurostimulation of the supratrochlear and supraorbital nerves with low-frequency (60 Hz) impulses. In the control group, participants received only drug therapy. One month after the end of the course of treatment, the intensity, frequency of headache, the amount of drugs taken, and the effect of headache on work ability were assessed. Statistical processing was performed in the IBM SPSS program using tests for nonparametric data and tests of signs and Wilcoxon. The results of the data were taken as significant at p 0.05.
 RESULTS. In the main group, there was a statistically significant (p 0.05) decrease in the frequency of headache episodes by 1.8 times, the number of analgesics consumed by 2.8 times, and the intensity of headache by 50%. We also observed a decrease in the effect of headache on the ability to work of patients from 79 to 47.3%. At the same time, there were patients whose headache did not affect their ability to work. In the control group we did not notice significant dynamics in the frequency of episodes and the intensity of headache.
 CONCLUSION. In our opinion, non-invasive percutaneous neurostimulation of the supratrochlear and supraorbital nerves is an additional option for preventive treatment in patients with chronic tension type headache.

Integrative Management of Pediatric Primary Headaches

Pediatric primary headache disorders are best treated using a comprehensive and integrative approach, due to the complex interactions between psychosocial and biological processes. Although more quality research is needed for treatment approaches to pediatric headaches, current practice management includes both pharmaceutical and nonpharmaceutical management. This article describes the integrative treatments used in a large regional pediatric headache program. Lifestyle approaches, nutraceuticals and dietary supplements, acupuncture, transcutaneous neurostimulation, relaxation, clinical hypnosis, biofeedback, and psychological services are discussed in detail for clinicians who may consider applying to their practice. [Pediatr Ann. 2019;48(6):e231-e235.].

Parasacral transcutaneous electrical stimulation for overactive bladder in children: An assessment per session

Neuromodulation has emerged as an effective therapeutic option for treatment of OAB in children. However, to our knowledge, no study has yet evaluated the results of neuromodulation on a session-by-session basis. The aim of this study was to evaluate the rate of complete response of overactive bladder (OAB) symptoms for each session of transcutaneous electrical stimulation (TENS), in a protocol of 20 sessions of therapy. This is a prospective study of the improvement of LUTS in children with isolated OAB. Included in this study were children over the age of 4 years who complained of urinary urgency, had bell-or tower-shaped uroflowmetry patterns, and post-void residual <10% of expected capacity for their age and/or less than 20mL. No patient was treated with an anticholinergic. Children were excluded with lower urinary tract symptoms (LUTS) secondary to urinary tract abnormalities. All patients underwent parasacral transcutaneous neurostimulation (TENS). The development of symptoms was observed right before each session using a visual analog scale (VAS) in which 0 means the absence of improvement and 10 represents maximum improvement of symptoms. We noted a complete resolution of symptoms (urgency, urge incontinence, frequency, and holding maneuvers) in some patients starting after the third session. In the 10th and 20th (last) sessions, 12 (17.4%) and 38 (55.1%) patients reported a complete resolution of symptoms. After complete resolution, 12 (17.4%) patients reported that their symptoms worsened to a minimum level of 40% improvement, but this was temporary and all returned to 100% improvement. Children who showed an improvement level greater than 50% in the fifth treatment session were 4.18 (p=0.007) times more likely to have success in the last treatment session. We found that a patient can experience complete symptom resolution as quickly as following the third session of TENS. The complete response rate progressively increases with the number of sessions, slowly until the 12th session and more rapidly after that. When symptom improvement of at least 50% is reported in the fifth session, there is a higher chance that the patient will have full resolution of symptoms at the end of treatment.

Electromyography data in chronic migraine patients by using neurostimulation with the Cefaly® device

The objective of this observational study is to report clinical and instrumental results obtained in 23 chronic migraine sufferers treated with transcutaneous neurostimulation with the Cefaly(®) device. The electrom yography (EMG) parameters of the patients monitored before and during neurostimulation with the Cefaly(®) device showed a significant increase in the EMG amplitude and frequency values in the frontalis, anterior temporalis, auricularis posterior and middle trapezius muscles. The Cefaly(®) device could act on the inhibitory circuit in the spinal cord thus causing a neuromuscular facilitation and may help reduce contraction of frontalis muscles.

New targets for migraine therapy.

The shift in our understanding of migraine as a vascular disorder to a brain disorder has opened new avenues for the development of novel therapeutics with neural targets. The advent of 5-HT1B/1D receptor agonists, the triptans, in the 1990s was a crucial step in the modern evolution of treatment. The use of triptans, like their predecessors, is limited by their vasoconstrictor effects, and new development has been slowed by poor academic research funding to identify new targets. The development of agents without vascular effects, such as calcitonin gene-related peptide receptor antagonists and selective serotonin 5-HT1F receptor agonists, will bring more effective treatments to a population currently without migraine-specific options. In addition, advances in understanding migraine pathophysiology have identified new potential pharmacologic targets such as acid-sensing ion channels, glutamate and orexin receptors, nitric oxide synthase (NOS), and transient receptor potential (TRP) channels. Although previous attempts to block subtypes of glutamate receptors, NOS, and TRP channels have had mixed outcomes, new molecules for the same targets are currently under investigation. Finally, an entirely new approach to migraine treatment with noninvasive neuromodulation via transcutaneous neurostimulation or transcranial magnetic stimulation is just beginning. Hopefully in the coming years we will see a new era of migraine therapy, with multiple classes of better-tolerated, more effective agents targeting diverse yet specific migraine mechanisms.

Prevention of migraine by supraorbital transcutaneous neurostimulation using the Cefaly® device (PREMICE): a multi-centre, randomized, sham-controlled trial

Subjects who have frequent migraine attacks (≥ 2 / month) are in need of a preventive anti-migraine treatment. Available preventive drugs have incomplete efficacy and/or unpleasant side effects.

A neuroprosthesis for tremor management through the control of muscle co-contraction

BackgroundPathological tremor is the most prevalent movement disorder. Current treatments do not attain a significant tremor reduction in a large proportion of patients, which makes tremor a major cause of loss of quality of life. For instance, according to some estimates, 65% of those suffering from upper limb tremor report serious difficulties during daily living. Therefore, novel forms for tremor management are required. Since muscles intrinsically behave as a low pass filter, and tremor frequency is above that of volitional movements, the authors envisioned the exploitation of these properties as a means of developing a novel treatment alternative. This treatment would rely on muscle co-contraction for tremor management, similarly to the strategy employed by the intact central nervous system to stabilize a limb during certain tasks.MethodsWe implemented a neuroprosthesis that regulated the level of muscle co-contraction by injecting current at a pair of antagonists through transcutaneous neurostimulation. Co-contraction was adapted to the instantaneous parameters of tremor, which were estimated from the raw recordings of a pair of solid state gyroscopes with a purposely designed adaptive algorithm. For the experimental validation, we enrolled six patients suffering from parkinsonian or essential tremor of different severity, and evaluated the effect of the neuroprosthesis during standard tasks employed for neurological examination.ResultsThe neuroprosthesis attained significant attenuation of tremor (p<0.001), and reduced its amplitude up to a 52.33±25.48%. Furthermore, it alleviated both essential and parkinsonian tremor in spite of their different etiology and symptomatology. Tremor severity was not a limiting factor on the performance of the neuroprosthesis, although there was a subtle trend towards larger attenuation of more severe tremors. Tremor frequency was not altered during neurostimulation, as expected from the central origin of Parkinson’s disease and essential tremor. All patients showed a good tolerance to neurostimulation in terms of comfort and absence of pain, and some spontaneously reported that they felt that tremor was reduced when the neuroprosthesis was activated.ConclusionsThe results presented herein demonstrate that the neuroprosthesis provides systematic attenuation of the two major types of tremor, irrespectively from their severity. This study sets the basis for the validation of the neuroprosthesis as an alternative, non-invasive means for tremor management.

Biomechanical loading as an alternative treatment for tremor: a review of two approaches.

Tremor is the most common movement disorder and strongly increases in incidence and prevalence with aging. Although not life threatening, upper-limb tremors hamper the independence of 65% of people suffering from them affected persons, greatly impacting their quality of life. Current treatments include pharmacotherapy and surgery (thalamotomy and deep brain stimulation). However, these options are not sufficient for approximately 25% of patients. Therefore, further research and new therapeutic options are required to effectively manage pathological tremor. This paper presents findings of two research projects in which two different wearable robots for tremor management were developed based on force loading and validated. The first consisted of a robotic exoskeleton that applied forces to tremulous limbs and consistently attenuated mild and severe tremors. The second was a neuroprosthesis based on transcutaneous neurostimulation. A total of 22 patients suffering from parkinsonian or essential tremor (ET) of different severities were recruited for experimental validation, and both systems were evaluated using standard tasks employed for neurological examination. The inclusion criterion was a postural and/or kinetic pathological upper-limb tremor resistant to medication. The results demonstrate that both approaches effectively suppressed tremor in most patients, although further research is required. The work presented here is based on clinical evidence from a small number of patients (n = 10 for robotic exoskeleton and n = 12 for the neuroprosthesis), but most had a positive response to the approaches. In summary, biomechanical loading is non-invasive and painless. It may be effective in patients who are insufficiently responsive (or have adverse reactions) to drugs or in whom surgery is contraindicated. This paper identifies and evaluates biomechanical loading approaches to tremor management and discusses their potential.

Prevention of Migraine by supraorbital transcutaneous neurostimulation with the Cefaly® device: the PREMICE trial.

Event Abstract Back to Event Prevention of Migraine by supraorbital transcutaneous neurostimulation with the Cefaly® device: the PREMICE trial. Delphine Magis1, 2, Bart Vandersmissen3, Sandrine Jeangette4, Luc Herroelen5, Michel Vandenheede6 and Jean Schoenen1* 1 ULg, Neurology & GIGA Neurosciences, Belgium 2 CHR Citadelle, Belgium 3 Erasme Hospital, Neurology, Belgium 4 CHU Charleroi, Belgium 5 AZ Gasthuisberg. KUL, Belgium 6 CHC Espérance, Belgium Background: Subjects who have frequent migraine attacks (≥ 2 / month) are in need of a preventive anti-migraine treatment. Available preventive drugs have incomplete efficacy and/or unpleasant side effects. Transcutaneous supraorbital neurostimulation has shown encouraging results for migraine preventive in pilot studies and it has no side effects. Objectives: To assess efficacy and safety in migraine prevention of transcutaneous supraorbital neurostimulation with the Cefaly® device in a multicentre, double-blinded, randomized, sham-controlled trial. Methods: After a 1-month run-in period, eligible patients were randomized 1:1 to verum or sham stimulation, and applied the Cefaly® device daily for 20 minutes druing 3 months. Primary outcome measures were change in monthly migraine days between the run-in month and the 3rd month of treatment, and percentage of subjects having a ≥ 50% reduction of monthly migraine days between run-in and 3rd month of treatment (“50% responders”). Results: Sixty-seven patients were randomized and included in the intention-to-treat analysis. During the 3rd month of treatment the mean number of migraine days was significantly lower compared to run-in in the verum (from 6.94+3.04 to 4.88+3.46; p=0.023), but not in the sham group (from 6.54+2.61 to 6.22+2.99; p=0.608). At 3 months of treatment the 50% responder rate was significantly greater (p=0.023) in the verum (38,1%) than in the sham group (12,1%). Monthly migraine attacks (p=0.044), monthly headache days (p=0.041) and monthly acute anti-migraine drug intake (p=0.007) were also significantly reduced in the verum group compared to the sham group. No adverse event or side effect occurred in either group. Conclusion: Transcutaneous supraorbital neurostimulation with the Cefaly® device was safe and effective as a preventive therapy for migraine. The therapeutic gain (26%) is within the range of those reported for other preventive drug and non-drug anti-migraine treatments. Keywords: Migraine, preventive therapy, supraorbital, transcutaneous, neurostimulation Conference: Belgian Brain Council, Liège, Belgium, 27 Oct - 27 Oct, 2012. Presentation Type: Poster Presentation Topic: Higher Brain Functions in health and disease: cognition and memory Citation: Magis D, Vandersmissen B, Jeangette S, Herroelen L, Vandenheede M and Schoenen J (2012). Prevention of Migraine by supraorbital transcutaneous neurostimulation with the Cefaly® device: the PREMICE trial.. Conference Abstract: Belgian Brain Council. doi: 10.3389/conf.fnhum.2012.210.00124 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 10 Aug 2012; Published Online: 12 Sep 2012. * Correspondence: Prof. Jean Schoenen, ULg, Neurology & GIGA Neurosciences, LIEGE, 4000, Belgium, jschoenen@ulg.ac.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Delphine Magis Bart Vandersmissen Sandrine Jeangette Luc Herroelen Michel Vandenheede Jean Schoenen Google Delphine Magis Bart Vandersmissen Sandrine Jeangette Luc Herroelen Michel Vandenheede Jean Schoenen Google Scholar Delphine Magis Bart Vandersmissen Sandrine Jeangette Luc Herroelen Michel Vandenheede Jean Schoenen PubMed Delphine Magis Bart Vandersmissen Sandrine Jeangette Luc Herroelen Michel Vandenheede Jean Schoenen Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Supraorbital transcutaneous neurostimulation has sedative effects in healthy subjects

BackgroundTranscutaneous neurostimulation (TNS) at extracephalic sites is a well known treatment of pain. Thanks to recent technical progress, the Cefaly® device now also allows supraorbital TNS. During observational clinical studies, several patients reported decreased vigilance or even sleepiness during a session of supraorbital TNS. We decided therefore to explore in more detail the potential sedative effect of supraorbital TNS, using standardized psychophysical tests in healthy volunteers.MethodsWe performed a double-blind cross-over sham-controlled study on 30 healthy subjects. They underwent a series of 4 vigilance tests (Psychomotor Vigilance Task, Critical Flicker Fusion Frequency, Fatigue Visual Numeric Scale, d2 test). Each subject was tested under 4 different experimental conditions: without the neurostimulation device, with sham supraorbital TNS, with low frequency supraorbital TNS and with high frequency supraorbital TNS.ResultsAs judged by the results of three tests (Psychomotor Vigilance Task, Critical Flicker Fusion Frequency, Fatigue Visual Numeric Scale) there was a statistically significant (p < 0.001) decrease in vigilance and attention during high frequency TNS, while there were no changes during the other experimental conditions. Similarly, performance on the d2 test was impaired during high frequency TNS, but this change was not statistically significant.ConclusionSupraorbital high frequency TNS applied with the Cefaly® device decreases vigilance in healthy volunteers. Additional studies are needed to determine the duration of this effect, the underlying mechanisms and the possible relation with the stimulation parameters. Meanwhile, this effect opens interesting perspectives for the treatment of hyperarousal states and, possibly, insomnia.

What is the efficacy of physical therapeutics for treating neuropathic pain in spinal cord injury patients?

Objective Evaluate the place and level of proof of physical therapeutics for treating neuropathic pain in spinal cord injury (SCI) patients. Method Literature review from three databases: PubMed, Embase, Pascal. The following keywords were selected: chronic neuropathic pain/non-pharmacological treatment; transcutaneous electrical nerve stimulation, physiotherapy, acupuncture, physical therapy, transcranial magnetic stimulation, heat therapy, ice therapy, cold therapy, massage, ultrasound, alternative treatment, complementary treatment, occupational therapy. The articles were analyzed using the double-reading mode. Results Three techniques emerge from the literature: magnetic or electrical transcranial stimulation, transcutaneous electrical nerve stimulation and acupuncture. Even though the first method is not easily accessible on a daily basis it is the one that yields the most promising results validated by Grade B studies. Healthcare professionals remain faithful to pain-relieving transcutaneous neurostimulation for both segmental neuropathic pain and below-level central neuropathic pain. Acupuncture is advocated by Canadian teams and could offer some interesting options; however, to this day, it does not have the methodological support and framework required to validate its efficacy. All other physical therapies are used in a random way. Only below-level massages are advocated by the patients themselves. Conclusion To this day, no study can validate the integration of physical therapy as part of the array of therapeutics used for treating neuropathic pain in SCI patients. In the future, it will require controlled and randomized therapeutic studies on homogenous groups of SCI patients, to control the various confusion factors.

TRANSCUTANEOUS NEUROMODULATION FOR THE URGE SYNDROME IN CHILDREN: A PILOT STUDY

Neuromodulation has been used to treat voiding dysfunction in adults. Due to its invasiveness it has rarely been used in children until now with the availability of transcutaneous neurostimulation. We evaluated clinical effects of transcutaneous neuromodulation on detrusor overactivity in children with the urge syndrome. Between May 1, 1998 and February 28, 1999, 15 girls (mean age 10.2 years) and 26 boys (mean age 10.7 years) with proved detrusor hyperactivity on videourodynamic study underwent neuromodulation. All children had been given anticholinergic therapy previously. Neurostimulation only was used in children in whom anticholinergics had no effect and those who had significant side effects. Anticholinergics were continued in children in whom they had a partial effect. Stimulation of 2 Hz. was applied for 2 hours every day. Surface electrodes were placed at the level of sacral root S3. After 1 month of trial stimulation those children who responded continued the treatment for 6 months, and were evaluated every 2 months. Of the 41 children 15 boys and 13 girls responded after 1 month of trial therapy with an increase in bladder capacity, decrease in urgency, decrease in incontinence and/or better sensitivity. Of the 13 children who did not respond 9 lacked motivation and 4 had no clinical effect despite motivation. After 6 months of therapy a significant increase in bladder capacity, decrease in voiding frequency and decrease in incontinence periods were noted. Adverse effects were not observed. One year after therapy relapse was noted in 7 patients, leaving 21 of 41 children definitively cured. Although preliminary, our results indicate that transcutaneous neuromodulation can improve symptoms of detrusor overactivity, as response to stimulation was noted in 76% of our patients and 56% were cured after 1 year. This therapeutic option is attractive for children because of its noninvasiveness and absence of adverse effects.

Changes in somatic sensitivity during transcutaneous electrical analgesia

Patients with chronic pain in one limb, who experienced pain reduction with transcutaneous neurostimulation, were examined for sensory perception in that limb before and during electrical analgesia. Contralateral limbs and normal subjects served as controls. Sensory stimuli were quantified, a range of stimuli were presented and data were analyzed according to sensory decision theory. Results showed that, compared to controls, painful limbs show considerable impairment in sensory sensitivity. With transcutaneous Neurostimulation, however, sensitivity is improved towards normal, whereas electrical stimulation slightly impairs perception in normal limbs. These results suggest that electrical analgesia involves both peripheral small-fiber blockade and large-fiber stimulation; the latter is more noticeable in the normal limb, but the former effect is predominant when pain reduction occurs in a painful limb.