Spinal Cord Stimulation in Patients With Chronic Pain and Restless Legs Syndrome: A Case Report

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.

Spinal cord stimulation in severe pharmacoresistant restless legs syndrome-two case reports

Restless legs syndrome is a prevalent, sleep-related sensorimotor disorder with relevant impact on the patients' quality of life. For patients suffering from severe, pharmacoresistant restless legs syndrome, few therapeutic options remain to alleviate symptoms. In this case series, two patients with severe, pharmacoresistant restless legs syndrome were treated with epidural spinal cord stimulation and repeatedly assessed with polysomnography, including sleep structure and periodic limb movements as objective biomarkers not subject to placebo effects, during a 6-month follow-up period. One of the patients experienced excellent short- and long-term efficacy on subjective symptom severity (International RLS Study group rating scale 1 vs. 34 points at 3 months) and objective sleep parameters such as sleep architecture and periodic limb movements during sleep, while the second patient only reported short-term benefits from spinal cord stimulation. Ultimately, both patients opted for removal of the device for inefficacy. Based on the complex pathophysiology of restless legs syndrome and presumed mechanism of action of spinal cord stimulation in chronic pain disorders, we provide a detailed hypothesis on the possible modulating effect of spinal cord stimulation on the key symptoms of restless legs syndrome. Apart from describing a new therapeutic option for pharmacoresistant restless legs syndrome, our findings might also provide further insights into the pathophysiology of the syndrome.

Potential therapeutic benefit of spinal cord stimulation in restless legs syndrome: scoping review and mechanistic considerations

BACKGROUND

Restless legs syndrome (RLS) is a prevalent sensorimotor disorder that can dramatically impair sleep quality, daytime function, and quality of life. Although many patients benefit from standard pharmacological therapy, some patients suffer from insufficient treatment response or medication intolerance. Novel treatment approaches are therefore necessary.

OBJECTIVE

Given the overlap between RLS and pain syndromes in both pathophysiological mechanisms and certain treatment options, we aimed to perform a scoping review of the available evidence on spinal cord stimulation (SCS) for RLS and discuss potential mechanistic implications.

METHODS

We identified a total of 16 cases of patients with RLS who underwent SCS, all from case reports or case series.

DISCUSSION

The published evidence is insufficient to assess SCS efficacy in patients with RLS, but SCS remains a promising investigational therapy in RLS on the basis of its potential mitigatory effects in the central hyperexcitability of the sensorimotor cortex through neuromodulation of spinal, subcortical, and cortical areas. A call for further research in this field is presented, with suggestions for future directions and trial designs.

Bilateral high-frequency noninvasive peroneal nerve stimulation evokes tonic leg muscle activation for sleep-compatible reduction of restless legs syndrome symptoms

STUDY OBJECTIVES

Restless legs syndrome (RLS) is a prevalent sleep disorder with limited treatment options. Bilateral high-frequency noninvasive peroneal nerve stimulation (NPNS) reduces RLS symptoms. Here, we sought to characterize the mechanism of action for NPNS and identify predictors of treatment response. We hypothesized that, similar to voluntary leg movements, NPNS reduces RLS symptoms by activating leg muscles.

METHODS

For 20 adults with moderate-severe RLS, we tested this hypothesis by recording surface electromyography (EMG) from the tibialis anterior leg muscle while administering NPNS at varying amplitudes to determine the minimum NPNS amplitude that evoked EMG activity (motor threshold) and maximal NPNS amplitude that was not distracting (therapeutic intensity level). Afterwards, participants self-administered NPNS (at the therapeutic intensity level) and sham control for 14 days, each in randomized order. Efficacy was defined as International RLS Study Group Rating Scale (IRLS) score difference for NPNS compared with sham.

RESULTS

NPNS consistently activated leg muscles; NPNS evoked EMG activity at the therapeutic intensity level for 19 of 20 participants (mean TIL: 26.6 mA, mean MT: 18.3 mA). Evoked EMG activity was tonic (not phasic) and sustained over time. Evoked EMG activity predicted efficacy; participants with lower motor thresholds had greater IRLS improvement (r = .45, P = .046). NPNS treatment did not interfere with self-reported sleep onset (NPNS: 16% of nights; sham: 11%; P = .629) and frequently improved self-reported sleep onset (NPNS: 52% of nights; sham: 15%; P = .002).

CONCLUSIONS

These results demonstrate that NPNS reduces RLS symptoms by activating afferent pathways, thereby generating tonic and sustained leg muscle activity without interfering with sleep.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Noninvasive Peripheral Nerve Stimulation for Restless Legs Syndrome; URL: https://clinicaltrials.gov/ct2/show/NCT04700683; Identifier: NCT04700683.

CITATION

Charlesworth JD, Adlou B, Singh H, Buchfuhrer MJ. Bilateral high-frequency noninvasive peroneal nerve stimulation evokes tonic leg muscle activation for sleep-compatible reduction of restless legs syndrome symptoms. J Clin Sleep Med. 2023;19(7):1199-1209.

Sleep-related motor disorders

Sleep-related motor disorders include non-rapid-eye movement (NREM) sleep parasomnias, rapid-eye movement (REM), sleep parasomnias including REM sleep behavior disorder (RBD), isolated motor phenomena in sleep, and periodic limb movement disorder. Restless legs syndrome (RLS) occurs while awake but is closely related to sleep and has a circadian pattern. The pontine sublaterodorsal tegmental nucleus has an important role in aligning motor control with sleep states, and dysfunction in this region can explain motor activities including cataplexy and loss of REM atonia seen in REM sleep behavior disorder. This chapter begins with a review of motor control in sleep. The rest of the chapter summarizes the clinical presentation, epidemiology, differential and treatment of NREM, REM, and isolated sleep-related motor disorders as well as restless legs syndrome.

Restless legs syndrome

Restless legs syndrome (RLS) is a common sensorimotor disorder characterized by an urge to move that appears during rest or is exacerbated by rest, that occurs in the evening or night and that disappears during movement or is improved by movement. Symptoms vary considerably in age at onset, frequency and severity, with severe forms affecting sleep, quality of life and mood. Patients with RLS often display periodic leg movements during sleep or resting wakefulness. RLS is considered to be a complex condition in which predisposing genetic factors, environmental factors and comorbidities contribute to the expression of the disorder. RLS occurs alone or with comorbidities, for example, iron deficiency and kidney disease, but also with cardiovascular diseases, diabetes mellitus and neurological, rheumatological and respiratory disorders. The pathophysiology is still unclear, with the involvement of brain iron deficiency, dysfunction in the dopaminergic and nociceptive systems and altered adenosine and glutamatergic pathways as hypotheses being investigated. RLS is poorly recognized by physicians and it is accordingly often incorrectly diagnosed and managed. Treatment guidelines recommend initiation of therapy with low doses of dopamine agonists or α₂δ ligands in severe forms. Although dopaminergic treatment is initially highly effective, its long-term use can result in a serious worsening of symptoms known as augmentation. Other treatments include opioids and iron preparations.

Noninvasive neuromodulation reduces symptoms of restless legs syndrome

STUDY OBJECTIVES

Restless legs syndrome (RLS) is a common neurological disorder characterized by an uncontrollable nocturnal urge to move the legs and often associated with chronic sleep disturbances. The most common treatments for RLS are medications that can have debilitating side-effects. Here, we evaluated a novel alternative modality of RLS treatment, noninvasive bilateral electrical stimulation of the common peroneal nerve.

METHODS

To assess the impact of this noninvasive peripheral nerve stimulation (NPNS) approach on RLS symptomatology, we conducted a multi-site randomized crossover study comparing NPNS to sham. RLS patients with moderate to severe RLS (n=37) self-administered NPNS and sham nightly for 14 days per treatment in randomized order.

RESULTS

NPNS resulted in a reduction in RLS severity of 6.81 points on the International RLS Rating Scale (IRLS) relative to 3.38 for sham (p<0.01) and a 66% clinically significant responder rate on the Clinical Global Impressions-Improvement (CGI-I) scale compared to 17% for sham (p<0.01). Subgroup analysis indicated that medication-resistant and medication-naïve participants both exhibited similarly robust responses. There were no moderate or serious device-related adverse events.

CONCLUSIONS

These results suggest that NPNS could be a promising alternative to pharmacological therapies for RLS and could provide a solution for medication-resistant RLS patients and for medication-naïve RLS patients who are unwilling or unable to take medication.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: Noninvasive Peripheral Nerve Stimulation for Restless Legs Syndrome; Identifier: NCT04700683; URL: https://clinicaltrials.gov/ct2/show/NCT04700683.