Botulinum Toxin in Restless Legs Syndrome-A Randomized Double-Blind Placebo-Controlled Crossover Study

Medication refractory restless legs syndrome: Real-world experience

BACKGROUND

Restless Legs Syndrome (RLS), impacting 5-13% of the population, poses challenges in long-term management. A knowledge gap exists in predicting resistance to first-line therapies.

OBJECTIVE

To identify demographic and clinical factors predictive of refractory cases.

METHODS

This retrospective study, conducted at the Parkinson's Disease Center and Movement Disorders Clinic, Baylor College of Medicine, Houston, Texas (January 2018 to September 2023) identified all patients with RLS evaluated during the pre-specified period and compared clinical and demographic data between medication-refractory ("malignant") group and "benign" cohort.

RESULTS

Among 132 patients with RLS, 23 (17.4%) were categorized as medication-refractory. This cohort was characterized by a significantly lower mean age at onset (39.3 vs. 53.5 years, p = 0.0005), longer disease duration (26.7 vs. 14.0 years), and a higher prevalence of a positive family history of RLS among first-degree relatives compared to the "benign" group (56.5% vs. 15.5%, p = 0.003). Furthermore, compared to the "benign" group, in the refractory group dopamine agonists were initiated as the primary medication at a significantly higher rate (p = 0.006).

CONCLUSION

Our study found that a younger age at disease onset, prolonged disease duration, initial use of dopamine agonists, and a positive family history increased the likelihood of refractory RLS. We caution against the use of dopamine agonists, especially in young patients with RLS. Additionally, botulinum toxin might be considered a viable second-line treatment, especially for patients with otherwise medically-refractory RLS.

Effectiveness and Safety of Botulinum Toxin Type A in Treatment of Restless Legs Syndrome: A Systematic Review and Meta-Analysis

Our study aimed to investigate the effectiveness and safety of botulinum toxin type A in patients with restless legs syndrome. We searched electronic databases, including PubMed, Cochrane Library, and Web of Science, up to 12 June 2021, for published articles. We enrolled randomized controlled clinical trials and non-randomized controlled studies involving patients with restless legs syndrome who were treated with botulinum toxin. Quality assessment was performed using the Cochrane risk of bias tool and Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies. As for the results, we included four articles comprising 62 participants, two studies were randomized controlled trials. Improvement in International Restless Legs Syndrome Study Group (IRLSSG) rating scale was observed in three studies. Adverse events were temporary and self-limited. Meta-analyses were performed, including the two randomized controlled trials with 27 participants. Compared with placebo, botulinum toxin injection significantly reduced scores of IRLSSG rating scale (SMD, −0.819, 95% confidence interval [CI], −1.377 to −0.262). A total of 11.8% (95% CI, 0.7–72.4%) of patients reported at least one adverse event. In conclusion, botulinum toxin injection may relieve restless legs syndrome related symptoms. However, decisive conclusions cannot be drawn because of the small number of patients included in our meta-analysis. Large-scale, randomized controlled trials are warranted to discover the optimal dose, safety, and long-term effect of intervention with botulinum toxin type A for patients with restless legs syndrome.

The Management of Restless Legs Syndrome: An Updated Algorithm

Restless legs syndrome (RLS) is a common disorder. The population prevalence is 1.5% to 2.7% in a subgroup of patients having more severe RLS with symptoms occurring 2 or more times a week and causing at least moderate distress. It is important for primary care physicians to be familiar with the disorder and its management. Much has changed in the management of RLS since our previous revised algorithm was published in 2013. This updated algorithm was written by members of the Scientific and Medical Advisory Board of the RLS Foundation based on scientific evidence and expert opinion. A literature search was performed using PubMed identifying all articles on RLS from 2012 to 2020. The management of RLS is considered under the following headings: General Considerations; Intermittent RLS; Chronic Persistent RLS; Refractory RLS; Special Circumstances; and Alternative, Investigative, and Potential Future Therapies. Nonpharmacologic approaches, including mental alerting activities, avoidance of substances or medications that may exacerbate RLS, and oral and intravenous iron supplementation, are outlined. The choice of an alpha₂-delta ligand as first-line therapy for chronic persistent RLS with dopamine agonists as a second-line option is explained. We discuss the available drugs, the factors determining which to use, and their adverse effects. We define refractory RLS and describe management approaches, including combination therapy and the use of high-potency opioids. Treatment of RLS in pregnancy and childhood is discussed.

Use of Botulinum Neurotoxin in Parkinson's Disease: A Critical Appraisal

For well over 30 years, the botulinum neurotoxin (BoNT) has been used for a large number of indications, some of which however have not been licensed. Admittedly, approval varies in many countries and this permits a large spectrum for evaluation. Thus, BoNT is used for patients with Parkinson’s disease (PD) and other Parkinson’s syndromes (PS) in varying degrees of frequency. We have to distinguish between (1) indications that are either approved or (2) those not approved, (3) indications that might be a result of PS and (4) finally those which appear independent of PS. The most important indication for BoNT in PS patients is probably sialorrhea, for which approval has been granted in the majority of countries. Cervical dystonia is a frequent symptom in PS, with anterocollis as a specific entity. A further indication is blepharospasm in the different forms, especially the inhibition of eyelid opening in atypical PS. The use of BoNT in cases of camptocormia, the Pisa syndrome and neck rigidity is still a matter of debate. In dystonia of the extremities BoNT can be recommended, especially in dystonia of the feet. One well-known indication, for which however sufficient data are still lacking, involves treating tremor with BoNT. As to autonomic symptoms: Focal hyperhidrosis and detrusor hyperactivity can be mentioned, in this last case BoNT has already been approved. A number of further but rare indications such as freezing-of-gait, dyskinesia, and dysphagia will be discussed and evaluated.

Botulinum Toxin in Movement Disorders: An Update

Since its initial approval in 1989 by the US Food and Drug Administration for the treatment of blepharospasm and other facial spasms, botulinum toxin (BoNT) has evolved into a therapeutic modality for a variety of neurological and non-neurological disorders. With respect to neurologic movement disorders, BoNT has been reported to be effective for the treatment of dystonia, bruxism, tremors, tics, myoclonus, restless legs syndrome, tardive dyskinesia, and a variety of symptoms associated with Parkinson's disease. More recently, research with BoNT has expanded beyond its use as a powerful muscle relaxant and a peripherally active drug to its potential central nervous system applications in the treatment of neurodegenerative disorders. Although BoNT is the most potent biologic toxin, when it is administered by knowledgeable and experienced clinicians, it is one of the safest therapeutic agents in clinical use. The primary aim of this article is to provide an update on recent advances in BoNT research with a focus on novel applications in the treatment of movement disorders. This comprehensive review of the literature provides a critical review of evidence-based clinical trials and highlights recent innovative pilot studies.

Use of botulinum toxin for movement disorders

The term movement disorders encompasses all disorders hypokinetic and hyperkinetic, which were previously known as extrapyramidal syndromes. With the definition of movement disorders and their diagnostic criteria and classifications, new studies for therapeutics could be performed. New drugs were launched, functional neurosurgery was developed, and the introduction of botulinum toxin (BoNT) for hyperkinesias was introduced. BoNT is an important therapy for dystonia, tics, myoclonus, and tremors. The aim of this review is to present the new and well-established uses of BoNT for movement disorders.