Botulinum toxin for writer's cramp: a randomised, placebo-controlled trial and 1-year follow-up

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.

Does the guidance method affect the doses of botulinum toxin in writer's cramp?

PURPOSE

Botulinum neurotoxin (BoNT) injections are the main medical treatment of writer's cramp. When the outcome is favourable, patients usually receive injections several times per year in the long-term. However, we know little about the course of BoNT doses and nothing about the impact of the guidance method on the clinical outcome or injection strategy.

METHODS

We studied, in the long-term, the doses of BoNT and the target muscles in a group of patients with writer's cramp, according to the guidance method (electrical stimulation or ultrasound). Patients received at least three injection cycles guided by electrical stimulation, followed by at least three injection cycles guided by ultrasound.

RESULTS

Twenty-four patients were included. More target muscles were injected after switching to ultrasound guidance, especially the flexor carpi ulnaris and the flexor carpi radialis. The mean dose by muscle was lower when ultrasound guidance was used. When using electrical stimulation guidance, the dose in the flexors of the fingers decreased in the long-term, but increased in the flexors of the wrist. The course of the BoNT doses and of the number of target muscles per cycle were not the same during the first period (electrical stimulation) and the second period (ultrasound).

CONCLUSIONS

Switching to ultrasound guidance, the BoNT dose decreased, mainly in the flexors of the wrist. Based on the results of our study, we suggest a starting dose in several muscles (flexor carpi ulnaris, flexor carpi radialis, flexor digitorum profundus and flexor pollicis longus).

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.

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.

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

Task-specific focal dystonia is characterized by muscle contraction(s) during a specific task, resulting in abnormal postures or movements. Specifically, writer’s cramp involves the upper extremity during the act of writing. Musician’s dystonia has a highly variable presentation, and thus makes therapeutic options more limited. Treatments include oral pharmacologic agents, neuromodulation, surgery and, most often, botulinum toxin (BoNT) injection. Selection of target muscles for toxin injection continues to be an area of active research for these task-specific movements. We present a review of the literature selected from a predefined search of the MEDLINE and ClinicalTrials.gov databases. We include six controlled studies of botulinum toxin for the management of writer’s cramp and focal task-specific dystonia (FTSD), including musician’s dystonia. Overall, 139 patients were included across all studies, with 99 individuals injected for writer’s cramp and the remaining 40 individuals with FTSD. The age range of all patients was 18–80 years old. We included studies that utilized only the BoNT-A serotype. These studies utilized various severity scales to quantify response to toxin injection, with ratings of instrument or pen control included as subjective ratings. Of the included 139 patients in this review, pooled data for toxin response show that 73% of patients who received the drug demonstrated improvement. Specific techniques for muscle localization and targeting were difficult to study as variable methods were employed. This remains an area of ongoing exploration.

Treatment of focal hand dystonia: current status

BACKGROUND

Focal hand dystonia (FHD) is usually adult-onset focal dystonia that can be associated with marked occupational and functional disability leading to reduced quality of life.

METHODS

Relevant studies on treatment options for FHD, their limitations, and current recommendations were reviewed using the PubMed search until March 31, 2021. Besides, the reference lists of the retrieved publications were manually searched to explore other relevant studies.

RESULTS

and conclusion Currently, botulinum toxin has the best evidence for treatment of FHD, and 20-90% of patients experience symptomatic improvement. However, its benefit is often limited by the reduction of muscle tonus acting on the muscle spindle. Different surgical modalities that have been used to treat focal hand dystonia include lesional surgery, deep brain stimulation, and magnetic resonance-guided focused ultrasound thalamotomy. Recent studies exploring the role of behavioral techniques, sensorimotor training, and neuromodulation for the treatment of focal hand dystonia have reported good outcomes, but larger studies are required before implementing these interventions in practice.

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.

Treatment of Dystonia: Medications, Neurotoxins, Neuromodulation, and Rehabilitation

Dystonia is a complex disorder with numerous presentations occurring in isolation or in combination with other neurologic symptoms. Its treatment has been significantly improved with the advent of botulinum toxin and deep brain stimulation in recent years, though additional investigation is needed to further refine these interventions. Medications are of critical importance in forms of dopa-responsive dystonia but can be beneficial in other forms of dystonia as well. Many different rehabilitative paradigms have been studied with variable benefit. There is growing interest in noninvasive stimulation as a potential treatment, but with limited long-term benefit shown to date, and additional research is needed. This article reviews existing evidence for treatments from each of these categories. To date, there are many examples of incomplete response to available treatments, and improved therapies are needed.

FDA Approvals and Consensus Guidelines for Botulinum Toxins in the Treatment of Dystonia

In 2016, the American Academy of Neurology (AAN) published practice guidelines for botulinum toxin (BoNT) in the treatment of blepharospasm, cervical dystonia, adult spasticity, and headache. This article, focusing on dystonia, provides context for these guidelines through literature review. Studies that led to Food and Drug Administration (FDA) approval of each toxin for dystonia indications are reviewed, in addition to several studies highlighted by the AAN guidelines. The AAN guidelines for the use of BoNT in dystonia are compared with those of the European Federation of the Neurological Societies (EFNS), and common off-label uses for BoNT in dystonia are discussed. Toxins not currently FDA-approved for the treatment of dystonia are additionally reviewed. In the future, additional toxins may become FDA-approved for the treatment of dystonia given expanding research in this area.

Focal limb dystonia and tremor: Clinical update

The association between tremor and dystonia has been known for many decades. Dystonic tremor is seen in the body part affected with dystonia. Tremor and dystonia can also co-exist in different body parts. Subtle dystonic posturing can be missed in patients with upper limb tremor and these patients are often misdiagnosed as essential tremor. Careful clinical examination and electrophysiology may help in differentiating classical essential tremor from dystonic tremor. Writer's cramp, a common focal hand dystonia can mimic primary writing tremor when the dystonic posturing is subtle. Oral medications have limited therapeutic efficacy. Botulinum toxin is considered as first line therapy for focal limb dystonia and is also effective in the treatment of tremor. Surgical options are reserved for cases refractory to medical therapy. In this review, we summarize the current state of knowledge of focal limb dystonia and tremor with a focus on underlying neurophysiology in these conditions.

Botulinum neurotoxin treatment in jerky and tremulous functional movement disorders: a double-blind, randomised placebo-controlled trial with an open-label extension

OBJECTIVE

To study the effect of botulinum neurotoxin (BoNT) treatment in jerky and tremulous functional movement disorders (FMD).

METHODS

Patients with invalidating, chronic (>1 year) symptoms were randomly assigned to two subsequent treatments with BoNT or placebo every 3 months with stratification according to symptom localisation. Improvement on the dichotomised Clinical Global Impression-Improvement scale (CGI-I) (improvement vs no change or worsening) at 4 months, assessed by investigators blinded to the allocated treatment was the primary outcome. Subsequently all patients were treated with BoNT in a ten month open-label phase.

RESULTS

Between January 2011 and February 2015 a total of 239 patients were screened for eligibility of whom 48 patients were included. No difference was found on the primary outcome (BoNT 16 of 25 (64.0%) vs Placebo 13 of 23 patients (56.5%); proportional difference 0.075 (95% CI -0.189 to 0.327; p=0.77). Secondary outcomes (symptom severity, disease burden, disability, quality of life and psychiatric symptoms) showed no between-group differences. The open-label phase showed improvement on the CGI-I in 19/43 (44.2%) of remaining patients, with a total of 35/43 (81.4%) improvement compared with baseline.

CONCLUSIONS

In this double-blind randomised controlled trial of BoNT for chronic jerky and tremulous FMD, we found no evidence of improved outcomes compared with placebo. Motor symptoms improved in a large proportion in both groups which was sustained in the open-label phase. This study underlines the substantial potential of chronic jerky and tremulous FMD patients to recover and may stimulate further exploration of placebo-therapies in these patients.

TRIAL REGISTRATION NUMBER

NTR2478.

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.

Botulinum Toxin for the Treatment of Focal Task-Specific Hand Dystonias: Systematic Review and Meta-Analysis

Objective:

Botulinum Toxin (BTX) has become a widely used treatment in several dystonic conditions, but the evidence for its efficacy has largely come from open trials and expert opinion. This systematic review examined the efficacy and safety of BTX in the treatment of Focal Hand Dystonia (FHD) in Randomized Controlled Trials (RCTs).

Methods:

We searched Ovid MEDLINE, EMBASE, Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts of Reviews of Effects (DARE), Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, SPORT Discus, SCOPUS, Web of Science, PEDro, ClinicalTrials.gov, and the International Clinical Trials Registry Platform (ICTRP) for randomized, placebo-controlled trials on the use of BTX for FHD.

Results:

Of 1,116 publications retrieved from the databases searched, three publications were included. The evidence identified pertains to focal task-specific hand dystonias. Sixty-nine participants were involved in the three RCTs with a mean duration of symptoms of 7.5 years. Participants were assessed using a combination of self-reported and functional performance outcome measures following injections of BTX subtype A (BTX-A) or placebo. The Oxford Quality Scale was used to assess the included studies, and the three studies each scored 3/5 or above. The included studies reported no adverse events with BTX-A use, other than muscle weakness and pain at the injection sites.

Conclusion:

The number of participants included in these three trials is too small to draw dependable conclusions about the efficacy and safety of BTX-A for FHD. There is currently not enough evidence to recommend the routine use of BTX-A for FHD.

The Use of Botulinum Toxin for Treatment of the Dystonias

Dystonias are characterized by involuntary muscle contractions, twisting movements, abnormal postures, and often tremor in various body regions. However, in the last decade several studies have demonstrated that dystonias are also characterized by sensory abnormalities. While botulinum toxin is the gold standard therapy for focal dystonia, exactly how it improves this disorder is not entirely understood. Neurophysiological studies in animals and humans have clearly demonstrated that botulinum toxin improves dystonic motor manifestations by inducing chemodenervation, therefore weakening the injected muscles. In addition, neurophysiological and neuroimaging evidence also suggests that botulinum toxin modulates the activity of various neural structures in the CNS distant from the injected site, particularly cortical motor and sensory areas. Concordantly, recent studies have shown that in patients with focal dystonias botulinum toxin ameliorates sensory disturbances, including reduced spatial discrimination acuity and pain. Overall, these observations suggest that in these patients botulinum toxin-induced effects encompass complex mechanisms beyond chemodenervation of the injected muscles.

Full recovery from drummer's dystonia with foot and arm symptoms after stereotactic ventro-oral thalamotomy: a case report

Ventro-oral (Vo) thalamotomy is effective in patients with focal task-specific dystonias (FTSDs), but only in those with upper-limb symptoms. We describe a patient with drummer's dystonia who completely recovered after Vo thalamotomy. A 37-year-old man who started playing drums at 14 began having difficulty performing fine movements with his right foot when drumming at 22. He experienced right hand cramps while drumming 3 months before visiting our hospital. He was diagnosed with FTSD. Left Vo thalamotomy was performed, which led to complete improvement of symptoms. Vo thalamotomy may be effective for FTSD patients with upper- and lower-extremity symptoms.

Botulinum Toxin Treatment of Movement Disorders

Botulinum neurotoxins (BoNTs) are now among the most widely used therapeutic agents in clinical medicine with indications applied to the fields of movement disorders, pain disorders, and autonomic dysfunction. In this literature review, the efficacy and utility of BoNTs in the field of movement disorders are assessed using the criteria of the Guideline Development Subcommittee of the American Academy of Neurology. The literature supports a level A efficacy (established) for BoNT therapy in cervical dystonia and a level B efficacy (probably effective) for blepharospasm, hemifacial spasm, laryngeal dystonia (spasmodic dysphonia), task-specific dystonias, essential tremor, and Parkinson rest tremor. It is the view of movement disorder experts, however, that despite the level B efficacy, BoNTs should be considered treatment of first choice for blepharospasm, hemifacial spasm, laryngeal, and task-specific dystonias. The emerging data on motor and vocal tics of Tourette syndrome and oromandibular dystonias are encouraging but the current level of efficacy is U (undetermined) due to lack of published high-quality studies.

A unifying motor control framework for task-specific dystonia

Task-specific dystonia is a movement disorder characterized by a painless loss of dexterity specific to a particular motor skill. This disorder is prevalent among writers, musicians, dancers and athletes. No current treatment is predictably effective, and the disorder generally ends the careers of affected individuals. Traditional disease models of dystonia have a number of limitations with regard to task-specific dystonia. We therefore discuss emerging evidence that the disorder has its origins within normal compensatory mechanisms of a healthy motor system in which the representation and reproduction of motor skill are disrupted. We describe how risk factors for task-specific dystonia can be stratified and translated into mechanisms of dysfunctional motor control. The proposed model aims to define new directions for experimental research and stimulate therapeutic advances for this highly disabling disorder.

The direct basal ganglia pathway is hyperfunctional in focal dystonia

See Fujita and Eidelberg (doi:10.1093/brain/awx305) for a scientific commentary on this article. Focal dystonias are the most common type of isolated dystonia. Although their causative pathophysiology remains unclear, it is thought to involve abnormal functioning of the basal ganglia-thalamo-cortical circuitry. We used high-resolution research tomography with the radioligand 11C-NNC-112 to examine striatal dopamine D1 receptor function in two independent groups of patients, writer’s cramp and laryngeal dystonia, compared to healthy controls. We found that availability of dopamine D1 receptors was significantly increased in bilateral putamen by 19.6–22.5% in writer’s cramp and in right putamen and caudate nucleus by 24.6–26.8% in laryngeal dystonia (all P ≤ 0.009). This suggests hyperactivity of the direct basal ganglia pathway in focal dystonia. Our findings paralleled abnormally decreased dopaminergic function via the indirect basal ganglia pathway and decreased symptom-induced phasic striatal dopamine release in writer’s cramp and laryngeal dystonia. When examining topological distribution of dopamine D1 and D2 receptor abnormalities in these forms of dystonia, we found abnormal separation of direct and indirect pathways within the striatum, with negligible, if any, overlap between the two pathways and with the regions of phasic dopamine release. However, despite topological disorganization of dopaminergic function, alterations of dopamine D1 and D2 receptors were somatotopically localized within the striatal hand and larynx representations in writer’s cramp and laryngeal dystonia, respectively. This finding points to their direct relevance to disorder-characteristic clinical features. Increased D1 receptor availability showed significant negative correlations with dystonia duration but not its severity, likely representing a developmental endophenotype of this disorder. In conclusion, a comprehensive pathophysiological mechanism of abnormal basal ganglia function in focal dystonia is built upon upregulated dopamine D1 receptors that abnormally increase excitation of the direct pathway, downregulated dopamine D2 receptors that abnormally decrease inhibition within the indirect pathway, and weakened nigro-striatal phasic dopamine release during symptomatic task performance. Collectively, these aberrations of striatal dopaminergic function underlie imbalance between direct and indirect basal ganglia pathways and lead to abnormal thalamo-motor-cortical hyperexcitability in dystonia.

Inhibitory rTMS applied on somatosensory cortex in Wilson's disease patients with hand dystonia

Hand dystonia is a common complication of Wilson's disease (WD), responsible for handwriting difficulties and disability. Alteration of sensorimotor integration and overactivity of the somatosensory cortex have been demonstrated in dystonia. This study investigated the immediate after effect of an inhibitory repetitive transcranial magnetic stimulation (rTMS) applied over the somatosensory cortex on the writing function in WD patients with hand dystonia. We performed a pilot prospective randomized double-blind sham-controlled crossover rTMS study. A 20-min 1-Hz rTMS session, stereotaxically guided, was applied over the left somatosensory cortex in 13 WD patients with right dystonic writer's cramp. After 3 days, each patient was crossed-over to the alternative treatment. Patients were clinically evaluated before and immediately after each rTMS session with the Unified Wilson's Disease rating scale (UWDRS), the Writers' Cramp Rating Scale (WCRS), a specifically designed scale for handwriting difficulties in Wilson's disease patients (FAR, flow, accuracy, and rhythmicity evaluation), and a visual analog scale (VAS) for handwriting discomfort. No significant change in UWDRS, WCRS, VAS, or FAR scores was observed in patients treated with somatosensory inhibitory rTMS compared to the sham protocol. The FAR negatively correlated with UWDRS (r = -0.6; P = 0.02), but not with the WCRS score, disease duration, MRI diffusion lesions, or with atrophy scores. In our experimental conditions, a single inhibitory rTMS session applied over somatosensory cortex did not improve dystonic writer cramp in WD patients.

Research Priorities in Limb and Task-Specific Dystonias

Dystonia, which causes intermittent or sustained abnormal postures and movements, can present in a focal or a generalized manner. In the limbs, focal dystonia can occur in either the upper or lower limbs and may be task-specific causing abnormal motor performance for only a specific task, such as in writer’s cramp, runner’s dystonia, or musician’s dystonia. Focal limb dystonia can be non-task-specific and may, in some circumstances, be associated with parkinsonian disorders. The true prevalence of focal limb dystonia is not known and is likely currently underestimated, leaving a knowledge gap and an opportunity for future research. The pathophysiology of focal limb dystonia shares some commonalities with other dystonias with a loss of inhibition in the central nervous system and a loss of the normal regulation of plasticity, called homeostatic plasticity. Functional imaging studies revealed abnormalities in several anatomical networks that involve the cortex, basal ganglia, and cerebellum. Further studies should focus on distinguishing cause from effect in both physiology and imaging studies to permit focus on most relevant biological correlates of dystonia. There is no specific therapy for the treatment of limb dystonia given the variability in presentation, but off-label botulinum toxin therapy is often applied to focal limb and task-specific dystonia. Various rehabilitation techniques have been applied and rehabilitation interventions may improve outcomes, but small sample size and lack of direct comparisons between methods to evaluate comparative efficacy limit conclusions. Finally, non-invasive and invasive therapeutic modalities have been explored in small studies with design limitations that do not yet clearly provide direction for larger clinical trials that could support new clinical therapies. Given these gaps in our clinical, pathophysiologic, and therapeutic knowledge, we have identified priorities for future research including: the development of diagnostic criteria for limb dystonia, more precise phenotypic characterization and innovative clinical trial design that considers clinical heterogeneity, and limited available number of participants.

History of Botulinum Toxin Treatment in Movement Disorders

BACKGROUND

The frontiers of clinical medicine constantly expand as a result of the innovative efforts of visionary researchers and keen observations of seasoned clinicians. In medicine, rarely has a therapeutic agent been found efficacious in the management of so many symptoms and in such a relatively short time as botulinum toxin. One of the most notable contributions of botulinum toxin therapy in clinical medicine is in the field of movement disorders.

METHODS

The English literature was searched using the Yale search engine including but not limited to PubMed and Ovid. The search includes articles from January 1 1980 to March 1 2016.

RESULTS

A total of 2055 articles were identified. Of these, 132 met the criteria for this review.

DISCUSSION

This historical review highlights early and seminal contributions that have introduced the application of botulinum toxins in the field of movement disorders and provides evidence-based contributions that have established botulinum toxin as an effective treatment for abnormal movements.

Predicting Improvement in Writer's Cramp Symptoms following Botulinum Neurotoxin Injection Therapy

INTRODUCTION

Writer's cramp is a specific focal hand dystonia causing abnormal posturing and tremor in the upper limb. The most popular medical intervention, botulinum neurotoxin type A (BoNT-A) therapy, is variably effective for 50-70% of patients. BoNT-A non-responders undergo ineffective treatment and may experience significant side effects. Various assessments have been used to determine response prediction to BoNT-A, but not in the same population of patients.

METHODS

A comprehensive assessment was employed to measure various symptom aspects. Clinical scales, full upper-limb kinematic measures, self-report, and task performance measures were assessed for nine writer's cramp patients at baseline. Patients received two BoNT-A injections then were classified as responders or non-responders based on a quantified self-report measure. Baseline scores were compared between groups, across all measures, to determine which scores predicted a positive BoNT-A response.

RESULTS

Five of nine patients were responders. No kinematic measures were predictably different between groups. Analyses revealed three features that predicted a favorable response and separated the two groups: higher than average cramp severity and cramp frequency, and below average cramp latency.

DISCUSSION

Non-kinematic measures appear to be superior in making such predictions. Specifically, measures of cramp severity, frequency, and latency during performance of a specific set of writing and drawing tasks were predictive factors. Since kinematic was not used to determine the injection pattern and the injections were visually guided, it may still be possible to use individual patient kinematics for better outcomes.

A critical overview of the current myofascial pain literature - March 2016

The worldwide interest in myofascial pain syndrome (MPS) and trigger points (TrPs) is reflected in the increasing number of publications. In this overview of the literature, we included 26 studies, case reports and review articles by authors from 18 different countries. Several research groups are exploring the characteristic of TrPs such as Chen and colleagues, who continued their work on the quantification of the taut bands. Meng and colleagues studied the relationships between TrPs and central sensitization, while Yu and colleagues examined the electrophysiological characteristics that occur as a result of active TrPs. Several researchers used objective measurements to determine clinical outcomes, such as Koppenhaver and colleagues who measured objective changes in the function and nociceptive sensitivity of lumbar multifidus muscle subjects with low back pain. Turo and colleagues quantified muscle tissue changes after dry needling in chronic myofascial pain using elastography. Multiple studies explored various treatment options for TrPs, such as dry needling, injections with lidocaine or granisetron, traditional Thai massage, self-myofascial release, kinesiotaping, and monochromatic infrared photo energy, among others.

Writer's cramp

Writer's cramp is the most common form of focal, task-specific dystonia. Symptoms frequently evolve in the setting of repetitive hand movements and increased writing demands, and clinical presentations demonstrate a variety of different dystonic patterns of the upper extremity such as while writing or holding a writing utensil. However, why writer's cramp develops still remains much of a mystery. Clinical evaluation of patients with writer's cramp and various theories regarding its pathophysiology are reviewed. Treatment can be challenging and often involves a combination of pharmacologic (e.g., oral medications, botulinum toxin injections) and non-pharmacologic approaches (e.g., neurosurgical or neurostimulatory interventions, rehabilitation therapies, adaptive devices). Management strategies for writer's cramp using both of these approaches will be discussed.

Botulinum neurotoxins for the treatment of focal dystonias: Review of rating tools used in clinical trials

Botulinum neurotoxins (BoNTs) are used to achieve therapeutic benefit in focal dystonia. An expert panel recently reviewed published evidence on the efficacy of BoNTs for the treatment of focal dystonias and produced recommendations for clinical practice. Another panel reviewed the clinimetric properties of rating scales for dystonia and produced recommendations for current usage and future directions. Considering that the strength of evidence derives not only from the quality of the study design, but also from usage of validated outcome measures, we combined the information provided by these two recent reviews and assessed the appropriateness of the rating instruments used in clinical trials on BoNT treatment in focal dystonia. Data sources included all the publications on BoNT treatment for focal dystonias reviewed by the recent evidence-based analysis. We reviewed all rating instruments used to assess primary and secondary outcome following BoNT treatment. The publications were allocated into five topics according to the focal dystonia type reviewed in the meta-analysis: blepharospasm, oromandibular dystonia, cervical dystonia, upper limb dystonia, and laryngeal dystonia. For each topic, papers were divided, according to the terminology used in the meta-analysis, into placebo-controlled, active comparator and methodological or uncontrolled. For each topic we identified the rating tools used in each study class and annotated which were the mostly used in each focal dystonia type. Outcome measures included tools related to motor and non-motor features, such as pain and depression, and functional as well as health-related quality of life features. Patient- and investigator-reported outcomes were also included. Rating instruments were classified as recommended, suggested, listed or not included, based on recommendations produced by the rating scale task force. Both primary and secondary outcome measures were assessed. As a final step we compared current practice, as summarized by the meta-analysis, with the recommendations of the rating scales panel. For blepharospasm, three placebo-controlled trials used suggested scales, one active-comparator study used a recommended scale and three active-comparator studies used suggested scales. For oromandibular dystonia, one placebo-controlled study used a suggested scale. For cervical dystonia, six placebo-controlled trials used a recommended scale, four active-comparator trials used a recommended scale and one active-comparator study used a suggested scale. For upper limb and laryngeal dystonia, no trial used validated instruments. Appropriately designed studies should be based on recommended rating instruments. Therapeutic trials not using clinimetrically tested rating measures do not provide sufficient information on efficacy of BoNT treatment, even if the study design is robust. Further research is needed to develop and validate new tools to assess all types of focal dystonia and to apply them in prospective placebo-controlled clinical trials.

[Experience of botulinum toxin in treatment of writer's cramp]

OBJECTIVE

To evaluate the efficacy and safety of botulinum toxin type A (BTA) injections in patients with writer's cramp (WC).

MATERIAL AND METHODS

We treated 29 patients, in general, 49 BTA injections were performed. To determine points for the injections, we used ultrasound examination of the forearm including the time of writing.

RESULTS

Patients reported subjective improvement in 75.9% after the first injection. Positive results as assessed with the WCRS were seen in 82.7% of the patients. We observed muscle weakness in the hands of 17.2% of the patients. Most of the patients were satisfied with the result of the injection and agreed on the need to re-injection when clinical effect of BTA had decreased.

CONCLUSION

To determine the indications for BTA injections in PS, an individual approach to the development of schemes of injections and calculation of dose is needed. Treatment of BTA should be used in severe forms of WC with social significance to the patients.

A practical approach to management of focal hand dystonia

Dystonia can be focal, segmental, multifocal, generalized, or hemidystonia. Focal dystonia is localized to a specific part of the body. Overall upper limb is more commonly involved in focal dystonia than lower limb and since it starts from hand, focal hand dystonia (FHD) is a more accepted terminology. Writer's cramp and musician dystonia are commonest types of FHD. Typically this dystonia is task specific, but in some patients this specificity may be lost over a period of time. Segmental or generalized dystonia may also start as FHD, so a detailed clinical assessment is required, which should be supplemented by relevant investigations. Treatment includes oral medications, injection botulinum toxin, neurosurgery including neurostimulation, and rehabilitation. Role of injection botulinum toxin has been extensively studied in writer's cramp patients and found to be effective; however, selection of muscles and techniques of injection are crucial in getting best results.

Current uses of botulinum toxin A as an adjunct to hand therapy interventions of hand conditions

STUDY DESIGN

Literature review.

DISCUSSION

Botulinum toxin A, a neurotoxin causing temporary muscle paralysis at the neuromuscular junction, has been used to treat multiple acquired conditions of the hand and upper extremity. Initially approved for use in treating blepharospasm and strabismus in the 1980s, indications have expanded to include spasticity associated with cerebrovascular accidents, vasospastic disorders, focal dystonias, and pain conditions. This article reviews the current literature discussing the efficacy of botulinum toxin A in management of disorders of the hand and upper extremity relevant to hand therapists.

LEVEL OF EVIDENCE

NA.

Stereotactic neurosurgery for writer's cramp: report of two cases with an overview of the literature

BACKGROUND

Writer's cramp is a specific movement disorder with hand muscle cramps in writing, being classified into focal and action-specific dystonia. Stereotactic surgery, such as thalamotomy and deep brain stimulation (DBS), has been reported for writer's cramp; however, the number of reported cases is still scarce and surgical procedures are also controversial.

OBJECTIVES

In this study, therefore, we present 2 patients who underwent thalamotomy for writer's cramp and systematically review the literature on stereotactic surgery for writer's cramp.

METHODS

Case reports and literature review are presented.

RESULTS

Both patients underwent ventral oral nucleus (Vo) thalamotomy safely. Their symptoms completely disappeared after surgery and did not recur during follow-up periods. In the literature, a total of 31 cases were surgically treated for writer's cramp. Stereotactic surgery included thalamotomy in 25 cases and DBS in 6. The target included the Vo in 17 cases, the ventral intermediate nucleus (Vim) in 3, and both Vo and Vim in 7. Both procedures markedly improved or resolved the symptoms. Transient neurological deficits were observed in 16.0% of patients after thalamotomy.

CONCLUSIONS

The Vo may be the most effective target to treat writer's cramp. Both thalamotomy and DBS are feasible and effective, but thalamotomy would be a better option, especially in younger or high-risk patients.

Focal dystonia and the Sensory-Motor Integrative Loop for Enacting (SMILE)

Performing accurate movements requires preparation, execution, and monitoring mechanisms. The first two are coded by the motor system, the latter by the sensory system. To provide an adaptive neural basis to overt behaviors, motor and sensory information has to be properly integrated in a reciprocal feedback loop. Abnormalities in this sensory-motor loop are involved in movement disorders such as focal dystonia, a hyperkinetic alteration affecting only a specific body part and characterized by sensory and motor deficits in the absence of basic motor impairments. Despite the fundamental impact of sensory-motor integration mechanisms on daily life, the general principles of healthy and pathological anatomic–functional organization of sensory-motor integration remain to be clarified. Based on the available data from experimental psychology, neurophysiology, and neuroimaging, we propose a bio-computational model of sensory-motor integration: the Sensory-Motor Integrative Loop for Enacting (SMILE). Aiming at direct therapeutic implementations and with the final target of implementing novel intervention protocols for motor rehabilitation, our main goal is to provide the information necessary for further validating the SMILE model. By translating neuroscientific hypotheses into empirical investigations and clinically relevant questions, the prediction based on the SMILE model can be further extended to other pathological conditions characterized by impaired sensory-motor integration.

Dystonia

INTRODUCTION

Dystonia is usually a lifelong condition with persistent pain and disability. Focal dystonia affects a single part of the body; generalised dystonia can affect most or all of the body. It is more common in women, and some types of dystonia are more common in people of Ashkenazi descent.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments, surgical treatments, and physical treatments for focal and generalised dystonia? We searched: Medline, Embase, The Cochrane Library, and other important databases up to September 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 19 studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review, we present information relating to the effectiveness and safety of the following interventions: acupuncture, amantadine, baclofen, benzatropine, biofeedback, botulinum toxins, bromocriptine, carbamazepine, carbidopa/levodopa, clonazepam, clozapine, deep brain stimulation of thalamus and globus pallidus, diazepam, gabapentin, haloperidol, lorazepam, myectomy (for focal dystonia), occupational therapy, ondansetron, physiotherapy, pregabalin, procyclidine, selective peripheral denervation (for focal dystonia), speech therapy, tizanidine, trazodone hydrochloride, and trihexyphenidyl.

Treatment of dystonia

Selecting the appropriate treatment for dystonia begins with proper classification of disease based on age, distribution, and underlying etiology. The therapies available for dystonia include oral medications, botulinum toxin, and surgical procedures. Oral medications are generally reserved for generalized and segmental dystonia. Botulinum toxin revolutionized the treatment of focal dystonia when it was introduced for therapeutic purposes in the 1980s. Surgical procedures are available for medication-refractory dystonia, markedly affecting an individual's quality of life.

Striatal dopaminergic dysfunction at rest and during task performance in writer's cramp

Writer's cramp is a task-specific focal hand dystonia characterized by involuntary excessive muscle contractions during writing. Although abnormal striatal dopamine receptor binding has been implicated in the pathophysiology of writer's cramp and other primary dystonias, endogenous dopamine release during task performance has not been previously investigated in writer's cramp. Using positron emission tomography imaging with the D2/D3 antagonist 11C-raclopride, we analysed striatal D2/D3 availability at rest and endogenous dopamine release during sequential finger tapping and speech production tasks in 15 patients with writer's cramp and 15 matched healthy control subjects. Compared with control subjects, patients had reduced 11C-raclopride binding to D2/D3 receptors at rest in the bilateral striatum, consistent with findings in previous studies. During the tapping task, patients had decreased dopamine release in the left striatum as assessed by reduced change in 11C-raclopride binding compared with control subjects. One cluster of reduced dopamine release in the left putamen during tapping overlapped with a region of reduced 11C-raclopride binding to D2/D3 receptors at rest. During the sentence production task, patients showed increased dopamine release in the left striatum. No overlap between altered dopamine release during speech production and reduced 11C-raclopride binding to D2/D3 receptors at rest was seen. Striatal regions where D2/D3 availability at rest positively correlated with disease duration were lateral and non-overlapping with striatal regions showing reduced D2/D3 receptor availability, except for a cluster in the left nucleus accumbens, which showed a negative correlation with disease duration and overlapped with striatal regions showing reduced D2/D3 availability. Our findings suggest that patients with writer's cramp may have divergent responses in striatal dopamine release during an asymptomatic motor task involving the dystonic hand and an unrelated asymptomatic task, sentence production. Our voxel-based results also suggest that writer's cramp may be associated with reduced striatal dopamine release occuring in the setting of reduced D2/D3 receptor availability and raise the possibility that basal ganglia circuits associated with premotor cortices and those associated with primary motor cortex are differentially affected in primary focal dystonias.

Treatment with botulinum toxin: An update

Botulinum neurotoxin (BoNT) is a potent toxin produced by the anaerobic bacterium clostridium botulinum. It causes flaccid, long-lasting, local and reversible paralysis. In addition, BoNT inhibits the secretion of the exocrine glands and could have properties in the control of pain. Thus, BoNT is useful in the treatment of many neuromuscular conditions where an increase of muscle tone is associated with the pathogenic mechanism. Furthermore, BoNT is recommended in the treatment of some hypersecretion disorders of the exocrine gland and could play a role in the treatment of migraine and other chronic pain conditions. In the BoNT therapy adverse effects are usually mild and reversible. However, repeated injections of BoNT can lead to the development of neutralizing antibodies that can subsequently inhibit the biological activity of the toxin. In this sense, many factors can influence the immunogenicity of the BoNT, such as product-related factors, the dose of BoNT used, the frequency of injection and the previous exposure to the toxin. In this review, we are going to discuss the current clinical applications of BoNT with a special focus on evidence, doses, injection technique and adverse effects for those applications more frequently used in neurology, namely spasticity, blepharospasm, hemifacial spasm, cervical dystonia and other focal dystonias, as well as chronic migraine, tremor, sialorrhea, facial palsy, neurogenic bladder and many other neurological condition.

[Applications of botulinum toxin in Neurology]

At present, botulinum toxin (BT) is one of the most fundamental available drugs in Neurology, only comparable with levodopa. BT is currently used in those entities characterized by excessive muscle contraction, including dystonia and spasticity. In addition, BT has been used to control pain associated with increased muscle contraction in dystonia and spasticity, but also is useful to control chronic pain not associated with muscle contraction, such as chronic daily headache. Finally, BT is useful in sialorrhoea and bruxism. The mechanism of action is complex, mainly acting on terminal neuromuscular junction, but also exhibiting analgesic properties, probably through inhibition of pain neurotransmitters release.

Evidence-based review and assessment of botulinum neurotoxin for the treatment of movement disorders

Botulinum neurotoxin (BoNT) can be injected to achieve therapeutic benefit across a large range of clinical conditions. To assess the efficacy and safety of BoNT injections for the treatment of certain movement disorders, including blepharospasm, hemifacial spasm, oromandibular dystonia, cervical dystonia, focal limb dystonias, laryngeal dystonia, tics, and essential tremor, an expert panel reviewed evidence from the published literature. Data sources included English-language studies identified via MEDLINE, EMBASE, CINAHL, Current Contents, and the Cochrane Central Register of Controlled Trials. Evidence tables generated in the 2008 Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology (AAN) review of the use of BoNT for movement disorders were also reviewed and updated. The panel evaluated evidence at several levels, supporting BoNT as a class, the serotypes BoNT-A and BoNT-B, as well as the four individual commercially available formulations: abobotulinumtoxinA (A/Abo), onabotulinumtoxinA (A/Ona), incobotulinumtoxinA (A/Inco), and rimabotulinumtoxinB (B/Rima). The panel ultimately made recommendations for each therapeutic indication, based upon the strength of clinical evidence and following the AAN classification scale. For the treatment of blepharospasm, the evidence supported a Level A recommendation for BoNT-A, A/Inco, and A/Ona; a Level B recommendation for A/Abo; and a Level U recommendation for B/Rima. For hemifacial spasm, the evidence supported a Level B recommendation for BoNT-A and A/Ona, a Level C recommendation for A/Abo, and a Level U recommendation for A/Inco and B/Rima. For the treatment of oromandibular dystonia, the evidence supported a Level C recommendation for BoNT-A, A/Abo, and A/Ona, and a Level U recommendation for A/Inco and B/Rima. For the treatment of cervical dystonia, the published evidence supported a Level A recommendation for all four BoNT formulations. For limb dystonia, the available evidence supported a Level B recommendation for both A/Abo and A/Ona, but no published studies were identified for A/Inco or B/Rima, resulting in a Level U recommendation for these two formulations. For adductor laryngeal dystonia, evidence supported a Level C recommendation for the use of A/Ona, but a Level U recommendation was warranted for B/Rima, A/Abo, and A/Inco. For the treatment of focal tics, a Level U recommendation was warranted at this time for all four formulations. For the treatment of tremor, the published evidence supported a level B recommendation for A/Ona, but no published studies were identified for A/Abo, A/Inco, or B/Rima, warranting a Level U recommendation for these three formulations. Further research is needed to address evidence gaps and to evaluate BoNT formulations where currently there is insufficient or conflicting clinical data.

Botulinum toxin for the treatment of movement disorders

After botulinum toxin was initially used to treat strabismus in the 1970s, others started using it to treat movement disorders including blepharospasm, hemifacial spasm, cervical dystonia, spasmodic dysphonia, and oromandibular dystonia. It was discovered that botulinum toxin can be an effective treatment for focal movement disorders with limited side effects. Over the past three decades, various formulations of botulinum toxin have been developed and the therapeutic use of these toxins has expanded in movement disorders and beyond. We review the history and mechanism of action of botulinum toxin, as well as describe different formulations available and their potential therapeutic uses in movement disorders.

Task-specific dystonias: historical review--a new look at the classics

Although task-specific dystonias (TSD) have been described for almost two centuries, few entities have been characterised so variously as TSD. Over time TSD have been described as pure motor phenomena, "neurasthenic" symptoms, occupational hazards akin to repetitive strain, hysterical symptoms and finally… back to pure motor phenomena. A review of the classic literature can shed light on this subject and show that the same disease can be classified of different ways according to the dominant contemporary concepts over time. In any case, classic authors already defined TSD as motor phenomena of central origin.

Treatment of focal dystonia

OPINION STATEMENT

Dystonia is characterized by repetitive twisting movements or abnormal postures due to involuntary muscle activity. When limited to a single body region it is called focal dystonia. Examples of focal dystonia include cervical dystonia (neck), blepharospasm (eyes), oromandibular dystonia, focal limb dystonia, and spasmodic dysphonia, which are discussed here. Once the diagnosis is established, the therapeutic plan is discussed with the patients. They are informed that there is no cure for dystonia and treatment is symptomatic. The main therapeutic option for treating focal dystonias is botulinum toxin (BoNT). There have been several attempts to characterize the procedure, the type of toxin, dosage, techniques, and combination with physical measures in each of the focal dystonia forms. The general treatment principles are similar. The affected muscles are injected at muscle sites based on evidence and experience using standard dosages based on the type of toxin used. The injections are repeated after 3 to 6 months based on the individual response duration. In the uncommon event of nonresponse with BoNT, the dose and site are reassessed. Oral drug treatment could be considered as an additional option. Once the condition is thought to be medically refractory, the opinion from the deep brain stimulation (DBS) team for the suitability of the patient for DBS is taken. The successful use of DBS in cervical dystonia has led to increased acceptance for trial in other forms of focal dystonias. DBS surgery in focal dystonias other than cervical is, however, still experimental. The patients may be offered the surgery with adequate explanation of the risks and benefits. Patient education and directing the patients towards dystonia support groups and relevant websites that provide scientific information may be useful for long-term compliance and benefit.

Botulinum toxin as treatment for focal dystonia: a systematic review of the pharmaco-therapeutic and pharmaco-economic value

Focal dystonia is a common, invalidating neurologic condition characterized by involuntary, sustained muscle contractions causing twisting movements and abnormal postures in one body part. Currently, botulinum toxin is the treatment of first choice. We performed a systematic review towards the pharmaco-therapeutic and pharmaco-economic value of botulinum toxin as treatment for focal dystonia, which yielded the following results. Botulinum toxin is the most effective treatment for reducing dystonic symptoms measured with dystonia-specific and general questionnaires, and pain in patients with focal dystonia. Seventy-one percent of patients with cervical dystonia had a reduction in neck pain compared to 12 % in placebo groups. Adverse events occur in 58 % of patients during treatment with botulinum toxin compared to 46 % treated with placebo. Especially dry mouth, neck weakness, dysphagia, and voice changes are common. Adverse events are usually mild and self-limiting. Health-related quality of life, measured with the SF-36 is 20-50 points lower in patients with focal dystonia compared to controls and the effect of botulinum toxin on health-related quality of life is unclear. Botulinum toxin treatment is expensive because the drug itself is expensive. Yearly costs for treating a patient with focal dystonia with botulinum toxin range from EUR 347 to EUR 3,633 and the gain in QALYs with BTX treatment is small. Focal dystonia impairs the productivity and the ability to work. At start of botulinum toxin treatment only 47-50 % was working. Botulinum toxin partly improves this. Overall, we conclude that botulinum toxin is an expensive drug with good effects. From a societal perspective, the costs may well weigh up to the regained quality of life. However, the available literature concerning costs, health-related quality of life and labor participation is very limited. An extensive cost-effectiveness study should be performed incorporating all these aspects.