Botulinum Toxin Therapy in Writer's Cramp and Musician's Dystonia

Review: Botulinum Toxin for Treatment of Focal Limb Dystonia

Focal limb dystonias (FLDs) are abnormal postures and muscle contractions in an arm or leg that can occur in the setting of specific activities or without any stimulus. This pathology can have a profound impact on quality of life and potentially limit work in those whose dystonias are brought on by activities related to their occupations. Botulinum toxin (BoNT) is approved for use in the United States by the Food and Drug Administration for several indications, including cervical dystonia and blepharospasm, but not for FLD. Despite this limitation, BoNT is frequently used clinically for FLD, generally with individualized dosing based on patient need and clinician expertise. Various methods exist for targeting treatment to the specific affected muscles and assessing the benefit of treatment. Small clinical trials have demonstrated the efficacy of BoNT, but larger controlled studies are needed.

Patient Burden in Dystonia Diagnosis and Botulinum Toxin Treatment: A Nationwide Survey in Turkey

BACKGROUND

Understanding real-world experiences is crucial in determining the potential gaps in patient-centered healthcare in dystonia. We explored the challenges of people with dystonia (PwD) at the stages of diagnosis and botulinum neurotoxin (BoNT) treatment.

METHODS

A multicenter survey was conducted face-to-face across seven university hospitals in Turkey. PwD receiving BoNT treatment for at least 6 months were invited. Data on demographics, diagnostic journeys, and treatment experiences were collected and analyzed using descriptive statistics and regression models.

RESULTS

A total of 789 PwD participated, reporting significant burdens during both diagnostic and treatment stages. Diagnosis was delayed by approximately 1 year, with 15% receiving incorrect initial diagnoses. Additionally, 30.7% of PwD traveled to another city, and 42.6% applied to private clinics for diagnosis, leading to a substantial logistic and financial burden. The treatment stage revealed that a quarter of PwD had to travel significant distances every 3 months, or applied to a private clinic to receive BoNT injections, creating considerable cost and effort. In addition, PwD with oromandibular dystonia were three times and task-specific dystonia were around nine times less likely to be satisfied with BoNT treatment compared to facial dystonia. Alternative treatment was reported in 11%, with no substantial benefit.

CONCLUSIONS

The findings highlight critical unmet needs in the diagnostic and treatment processes for PwD. These include improvement in diagnostic accuracy, reduced travel and financial burdens, and enhanced treatment satisfaction. An action plan emphasizing resource utilization policies and educational activities for healthcare providers is essential to address these challenges.

Bibliometric analysis of research developments in oral and maxillofacial neuralgia from 2004 to 2023

This study employs bibliometric techniques to dynamically represent the research landscape of oral and maxillofacial neuralgia. Its goal is to pinpoint research hotspots and delineate forthcoming trends. A systematic search of the Web of Science Core Collection was performed using targeted keywords to retrieve literature from January 2004 to December 2023. Citespace version 6.2.6 was utilized to analyze countries, institutions, authors, co-cited journals, and keywords. The analysis indicates an annual increase in research literature on oral and maxillofacial neuralgia, albeit with a decline observed in the past 2 years. In the last 5 years, a total of 279 publications have been produced, predominantly by developed countries. The average betweenness centrality exceeds 0.1. Analysis of co-cited literature revealed 100 nodes, with research frontiers closely associated with trigeminal neuralgia, gamma knife radiosurgery, percutaneous balloon compression, among others. Keyword clustering analysis generated 61 nodes, primarily concentrated on 3 research areas: gamma knife, microvascular decompression, and hemifacial spasm. The emergence of keywords closely correlates with trigeminal neuralgia. Research frontiers in the field of oral and maxillofacial neuralgia are primarily focused on trigeminal neuralgia, with major therapeutic approaches including gamma knife radiosurgery and percutaneous balloon compression. These areas, along with botulinum toxin, represent current hotpots and are likely to drive the future direction of research in treating oral and maxillofacial neuralgia.

Clinical neurophysiology in the treatment of movement disorders: IFCN handbook chapter

In this review, different aspects of the use of clinical neurophysiology techniques for the treatment of movement disorders are addressed. First of all, these techniques can be used to guide neuromodulation techniques or to perform therapeutic neuromodulation as such. Neuromodulation includes invasive techniques based on the surgical implantation of electrodes and a pulse generator, such as deep brain stimulation (DBS) or spinal cord stimulation (SCS) on the one hand, and non-invasive techniques aimed at modulating or even lesioning neural structures by transcranial application. Movement disorders are one of the main areas of indication for the various neuromodulation techniques. This review focuses on the following techniques: DBS, repetitive transcranial magnetic stimulation (rTMS), low-intensity transcranial electrical stimulation, including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), and focused ultrasound (FUS), including high-intensity magnetic resonance-guided FUS (MRgFUS), and pulsed mode low-intensity transcranial FUS stimulation (TUS). The main clinical conditions in which neuromodulation has proven its efficacy are Parkinson's disease, dystonia, and essential tremor, mainly using DBS or MRgFUS. There is also some evidence for Tourette syndrome (DBS), Huntington's disease (DBS), cerebellar ataxia (tDCS), and axial signs (SCS) and depression (rTMS) in PD. The development of non-invasive transcranial neuromodulation techniques is limited by the short-term clinical impact of these techniques, especially rTMS, in the context of very chronic diseases. However, at-home use (tDCS) or current advances in the design of closed-loop stimulation (tACS) may open new perspectives for the application of these techniques in patients, favored by their easier use and lower rate of adverse effects compared to invasive or lesioning methods. Finally, this review summarizes the evidence for keeping the use of electromyography to optimize the identification of muscles to be treated with botulinum toxin injection, which is indicated and widely performed for the treatment of various movement disorders.

Zolpidem improves task-specific dystonia: A randomized clinical trial integrating exploratory transcranial magnetic stimulation and [18F] FDG-PET imaging

BACKGROUND

Task-specific dystonia (TSFD) is a disabling movement disorder. Effective treatment options are currently limited. Zolpidem was reported to improve primary focal and generalized dystonia in a proportion of patients. The mechanisms underlying its therapeutic effects have not yet been investigated.

METHODS

We conducted a randomized, double-blind, placebo-controlled, crossover trial of single-dose zolpidem in 24 patients with TSFD. Patients were clinically assessed using Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS), Writers' Cramp Rating Scale (WCRS), and Visual Analogue Scale (VAS), before and after receiving placebo and zolpidem. Transcranial magnetic stimulation was conducted on placebo and zolpidem to compare corticospinal excitability - active and resting motor thresholds (AMT and RMT), resting and active input/output curves and intracortical excitability - cortical silent period (CSP), short-interval intracortical inhibition curve (SICI), long-interval intracortical inhibition (LICI) and intracortical facilitation (ICF). Eight patients underwent brain FDG-PET imaging on zolpidem and placebo.

RESULTS

Zolpidem treatment improved TSFD. Zolpidem compared to placebo flattened rest and active input/output curves, reduced ICF and was associated with hypometabolism in the right cerebellum and hypermetabolism in the left inferior parietal lobule and left cingulum. Correlations were found between changes in dystonia severity on WCRS and changes in active input/output curve and in brain metabolism, respectively. Patients with lower RMT, and higher rest and active input/output curves exhibited better response to zolpidem compared to placebo.

CONCLUSIONS

Zolpidem improved TSFD by reducing corticomotor output and influencing crucial nodes in higher-order sensory and motor networks.

Genetic Update and Treatment for Dystonia

A neurological condition called dystonia results in abnormal, uncontrollable postures or movements because of sporadic or continuous muscular spasms. Several varieties of dystonia can impact people of all ages, leading to severe impairment and a decreased standard of living. The discovery of genes causing variations of single or mixed dystonia has improved our understanding of the disease's etiology. Genetic dystonias are linked to several genes, including pathogenic variations of VPS16, TOR1A, THAP1, GNAL, and ANO3. Diagnosis of dystonia is primarily based on clinical symptoms, which can be challenging due to overlapping symptoms with other neurological conditions, such as Parkinson's disease. This review aims to summarize recent advances in the genetic origins and management of focal dystonia.

Musician's dystonia in a percussionist - clinical video analysis and botulinum toxin intervention: a case report

OBJECTIVE

Musician's focal hand dystonia is a painless task-specific focal dystonia, which presents with involuntary movements, abnormal postures, and loss of fine motor dexterity. We report here the case of a 63-year-old male, percussionist, with african ethnicity, with musician's focal hand dystonia who was treated with botulinum toxin, and describe the results at 4-weeks follow up.

METHODS

Clinical examination and video analysis revealed abnormal flexion of the 3rd finger, followed by flexion of the 4th and 5th fingers while playing the congas. Based on these findings, a diagnosis of musician's focal hand dystonia was established. Ten units of botulinum toxin were injected into the muscle fibres of the flexor digitorum superficialis corresponding to the 4th finger using electromyography and ultrasound guidance. Four weeks later, the patient reported a subjective 60% improvement in his performance. He emphasized the effect of botulinum toxin on performance speed and tension over the forearm and hand.

CONCLUSION

Botulinum toxin is not a definitive treatment for musician's focal hand dystonia, but it may potentiate other definitive rehabilitation techniques. More research is needed to determine the long-term effects of botulinum toxin on function enhancement in musician's focal hand dystonia.

Treatment of task-specific dystonia in sports: A systematic review

Introduction

Task specific dystonia is a movement disorder only affecting a highly practiced skill and is found in a broad set of expert movements including in sports. Despite affecting many sports, there is no comprehensive review of treatment options, which is in contrast to better studied forms of task specific dystonia in musicians and writers. For this reason, studies involving an intervention to treat task specific dystonia in sports were systematically reviewed, with special attention for the quality of outcome measures.

Methods

The PICO systematic search strategy was employed on task-specific dystonia, and all synonyms. Inclusion criteria were peer reviewed published studies pertaining to sports, studies with a measurement and/or intervention in TSD, all in English. We excluded abstracts, expert opinions, narrative review articles, unpublished studies, dissertations and studies exclusively relating to choking. We included case reports, case studies and case-control studies.

Results

In April 2022 Pubmed, Embase, Web of Science, and Psychinfo were searched. Of the 7000 articles identified, 31 were included that described psychological and invasive and/or pharmacological interventions. There was a lack of formal standardized outcome measures in studies resulting in low quality evidence for the effectiveness of treatment options. A descriptive synthesis showed emotional regulation was effective, but was exclusively tried in golfers. Interventions like botulinum toxin or pharmacology had a similar effectiveness compared to studies in musicians dystonia, however there was almost no formal evidence for these treatments.

Conclusion

The quality of studies was low with a lack of standardized outcome measures. Future studies with larger cohorts and quantitative outcome measures are needed to improve understanding of treatments for task specific dystonia in athletes.

Structural basis of botulinum neurotoxin serotype A1 binding to human SV2A or SV2C receptors

Botulinum neurotoxin A1 (BoNT/A1) is the most potent natural poison in human. BoNT/A1 recognize the luminal domain of SV2A (LD-SV2A) and its glycosylation at position N573 (N573g) or the luminal domain of SV2C (LD-SV2C) and its glycosylation at position N559 (N559g) to bind neural membrane. Our computational data suggest that the N-glycan at position 480 (N480g) in the luminal domain of SV2C (LD-SV2C) indirectly enhanced the contacts of the neurotoxin surface with the second N-glycan at position 559 (N559g) by acting as a shield to prevent N559g to interact with residues of LD-SV2C. The absence of an N-glycan homologous to N480g in LD-SV2A leads to a decrease of the binding of N573g to the surface of BoNT/A1. Concerning the intermolecular interactions between BoNT/A and the protein part of LD-SV2A or LD-SV2C, we showed that the high affinity of the neurotoxin for binding LD-SV2C are mediated by a better compaction of its F557-F562 part provided by a π-π network mediated by residues F547, F552, F557 and F562 coupled with the presence of two aromatic residues at position 563 and 564 that optimize the binding of BoNT/A1 via cation-pi and CH-pi interaction. Finally, in addition to the well-known ganglioside binding site which accommodates a ganglioside on the surface of BoNT/A1, we identified a structure we coined the ganglioside binding loop defined by the sequence 1253-HQFNNIAK-1260 that is conserved across all subtypes of BoNT/A and is predicted to has a high affinity to interact with gangliosides. These data solved the puzzle generated by mutational studies that could be only partially understood with crystallographic data that lack both a biologically relevant membrane environment and a full glycosylation of SV2.

Botulinum toxin for motor disorders

Botulinum neurotoxins are a group of biological toxins produced by the gram-negative bacteria Clostridium botulinum. After intramuscular injection, they produce dose-related muscle relaxation, which has proven useful in the treatment of a large number of motor and movement disorders. In this chapter, we discuss the utility of botulinum toxin treatment in three major and common medical conditions related to the dysfunction of the motor system, namely dystonia, tremor, and spasticity. A summary of the existing literature is provided along with different techniques of injection including those recommended by the authors.

Efficacy and safety of botulinum toxin-A in writer’s cramp: a systematic review, meta-analysis, and meta-regression

Background

Botulinum toxin-A (BoNT) reduce over-firing of dystonic muscles, spasmodic contractions by enhancing function. We conducted a systematic review and random-effects meta-regression to investigate the efficacy and safety of BoNT in writer’s cramp (WC). Published electronic articles from inception till January 2022 were screened from four databases (Medline, Science Direct, Scopus, ProQuest). Effect sizes in the form of standardized mean differences were calculated for estimation of efficacy.

Results

Nineteen studies [six randomized control trials (RCTs) and 13 observational studies] involved 587 (514 experimental; 73 Controls) participants with mean age of 43.46 ± 8.84 years with mean duration of WC of 8.31 ± 5.35 years. Injection did not result in significant improvement in writing speed [standard mean difference (95% CI) 0.06 (− 0.35, 0.46)]. There was no significant difference in writing speed as compared to controls [standard mean difference (95% CI) − 0.51 (− 2.55, 1.52)]. The meta-analysis of observational studies showed a significant difference in the mean WC rating score [standard mean difference (95% CI) 0.54 (0.20, 0.88)]. Pooled analysis (observational studies and RCTs) demonstrated a significant difference in the mean Writer’s cramp rating score (WCRS) after BoNT [standard mean difference (95% CI) 0.75 (0.06, 1.44)]. No major safety concerns were reported in the included studies.

Conclusions

According to the meta-analysis of observational studies, BoNT injections are effective in WC for improving WCRS without major safety concerns. However, according to the meta-analysis of RCTs, there was no significant effect in efficacy with BoNT.