An overview of rehabilitation approaches for focal hand dystonia in musicians: A scoping review.

OBJECTIVE: To provide a comprehensive overview of rehabilitation treatment strategies for focal hand dystonia (FHD) in musicians, examining their evolution and effectiveness. DATA SOURCES: A systematic search of five databases, PubMed, PEDro, Cochrane Library, Trip, and Google Scholar, to identify relevant articles on FHD rehabilitation. The last search was performed on 20 December 2023. METHODS: Inclusion criteria were applied to 190 initially identified articles, resulting in 17 articles for review. Exclusions were made for duplicates, irrelevant titles, abstracts, and non-rehabilitation interventions. RESULTS: Ten different rehabilitation approaches were identified over 20 years. While no definitive intervention protocol exists, a multimodal approach is commonly recommended. CONCLUSIONS: This scoping review underscores the diversity of rehabilitation strategies for FHD. It suggests the potential of multimodal approaches, emphasizing the need for further large-scale clinical efficacy studies.

Rehabilitation of focal hand dystonia in musicians: a systematic review of the studies. / Rehabilitación de la distonía focal de mano en músicos: una revisión sistemática de los estudios.

INTRODUCTION: Focal hand dystonia in musicians is a task-specific movement disorder characterized by an involuntary loss of control and coordination of finger movements during instrumental playing. MATERIALS AND METHODS: Literature searches with the keywords 'dystonia' AND 'musician' AND 'finger' OR 'treatment' OR 'therapy' OR 'rehabilitation' were conducted in PubMed, EMBASE, Cochrane Library and Web of Science to perform the systematic review about the several strategies used to treat dystonia in musicians. The search was performed independently by two authors (R.C. and M.V.) from 6 April 2020 till 6 June 2020. The research identified a total of 423 articles. Seventy-seven selected articles were analysed by the reviewers. Thirty-six publications met the inclusion criteria and were included in the systematic review. RESULTS: The systematic review was performed to identify the main used treatments for dystonia in musicians. We defined the several techniques to better guide the physician to delineate a rehabilitation protocol adopting the better strategies described in the current literature. CONCLUSION: This systematic review tried to provide to the reader a complete overview of the literature of all possible different treatments for dystonia in musicians. A correct protocol could permit to improve the motor performance and the quality of life of musicians.

TITLE: Rehabilitación de la distonía focal de mano en músicos: una revisión sistemática de los estudios.Introducción. La distonía focal de la mano en los músicos es un trastorno del movimiento relacionado con una tarea específica, que se caracteriza por una pérdida involuntaria del control y la coordinación de los movimientos de los dedos al tocar un instrumento. Materiales y métodos. Se llevaron a cabo búsquedas bibliográficas con las palabras clave 'dystonia' (distonía) Y 'musician' (músico) Y 'finger' (dedo) O 'treatment' (tratamiento) O 'therapy' (terapia) O 'rehabilitation' (rehabilitación) en PubMed, EMBASE, Cochrane Library y Web of Science para realizar la revisión sistemática sobre las diversas estrategias usadas para tratar la distonía en los músicos. La búsqueda se realizó de forma independiente por dos autores (R.C. y M.V.) entre el 6 de abril de 2020 y el 6 de junio del mismo año. La investigación identificó un total de 423 artículos. Los encargados de la revisión analizaron 77 artículos que fueron previamente seleccionados. Treinta y seis publicaciones cumplieron con los criterios de inclusión y se incluyeron en la revisión sistemática. Resultados. La revisión sistemática se realizó para identificar los principales tratamientos utilizados para la distonía en músicos. Se definieron las diversas técnicas existentes para orientar mejor a los médicos a la hora de diseñar un protocolo de rehabilitación que adopte las mejores estrategias descritas en la bibliografía actual. Conclusión. Esta revisión sistemática intenta proporcionar al lector una mirada completa sobre todos los posibles tratamientos diferentes para la distonía en los músicos. Un protocolo correcto podría permitir mejorar el rendimiento motor y la calidad de vida de los músicos.

A therapy-led, multidisciplinary programme for treatment-resistant functional fixed dystonia.

Functional neurological disorder (FND) describes various neurological symptoms that are not explained by an organic aetiology. The condition has a poor prognosis. Despite this, there is sparse research that informs clinical interventions for FND, particularly when treating functional fixed dystonia. Our article has outlined an intervention for a patient with a treatment-resistant functional fixed dystonia that was informed by a biopsychosocial model, which aimed to rehabilitate the patient's functional motor symptoms. This led to favourable outcomes including restoring full range of movement in the patient's right foot and improvements in routine outcome measurement scores. The patient also described the programme as life-changing and was able to re-engage in meaningful and purposeful activities.

What can kinematic studies tell us about the mechanisms of dystonia?

Clinical movement disorders are classified by an algorithm implemented by a practising movement disorder specialist based on information extracted during the history and clinical examination of a patient. Most simply, dystonia, is a classifier which is reached when a predominant abnormality of posture is noted. In this chapter we summarize studies that have used a variety of techniques to probe beyond the clinical examination and study kinematic features experimentally. We also outline our experimental work in DYT1 dystonia, a group of patients that share a genetically homogenous etiology and can be considered a prototypical dystonic disorder. Our results build on previous studies, confirming that motor variability on a trial-by-trial basis is selectively increased and provide evidence that increases in variability are negatively related to forms of motor learning essential for healthy motor control. Potential neural correlates of increased motor variability are discussed and the implications such work has for the rehabilitation of patients with dystonia are also highlighted.

Assessment of the effects of Kinesiotaping on musical motor performance in musicians suffering from focal hand dystonia: a pilot study.

OBJECTIVE: The aim of this study was to explore the immediate and short-term effects of a Correction Kinesiotaping intervention on fine motor control in musicians with focal hand dystonia. DESIGN: A single-blinded, single-arm repeated measures, pilot study. SETTING: Medical outpatient clinic. SUBJECTS: Seven musicians diagnosed with focal hand dystonia. INTERVENTIONS: Musicians performed musical exercises under the following conditions: without Kinesiotape (baseline), during a Correction Kinesiotaping intervention and immediately after tape removal (block 1) and during a Sham Kinesiotaping intervention and immediately after tape removal (block 2). Blocks were randomly presented across participants. A tailored Correction Kinesiotaping intervention on affected fingers was provided based on the dystonic pattern that each patient manifested while playing. MAIN MEASURES: Motor performance was video-documented and independent experts blindly assessed the general performance and fingers' posture on visual analogue scales. Also, musicians' self-reports of the musical abilities were evaluated. Finally, electromyographic activity and coactivation index of wrist antagonist muscles were analyzed. RESULTS: No significant differences in effects between Correction Kinesiotaping and Sham Kinesiotaping were reported by the experts, either for general performance (P > 0.05) or for fingers' posture (P > 0.05); any subtle benefits observed during Correction Kinesiotaping were lost after the tape was removed. Musicians estimated that Correction Kinesiotaping was ineffective in improving their musical abilities. Also, no significant changes with respect to the coactivation index (P > 0.05) were found among the conditions. CONCLUSION: Correction Kinesiotaping intervention may not be useful to reduce dystonic patterns, nor to improve playing ability, in musicians with focal hand dystonia.

Neuromuscular Re-Education Programs for Musicians with Focal Hand Dystonia: A Systematic Review.

OBJECTIVE: The purpose of this systematic review was to evaluate the effectiveness of neuromuscular re-education programs on reducing abnormal movements during instrument play in musicians with focal hand dystonia (FHD). METHODS: A systematic literature search of published articles was performed. Databases searched included MEDLINE, CINAHL, PsycINFO, OTseeker, and the Cochrane Library. Additional articles were identified from reference lists. Studies meeting inclusion criteria were independently assessed by the two coauthors for eligibility and quality of methods. Study data were summarized in a critical appraisal chart. RESULTS: Nine studies met the inclusion criteria for review, including 1 non-randomized two-group study, 6 single-group repeated measures studies, and 2 single-subject studies. The studied neuromuscular re-education programs included constraint-induced therapy plus motor control retraining, sensory motor retuning, learning- based sensorimotor training, and slow-down exercise. CONCLUSIONS: The results of this review indicate there is moderate evidence to support the effectiveness of neuromuscular re-education programs on reducing abnormal movements during instrument play in musicians with FHD. However, additional research should evaluate the effectiveness of neuromuscular re-education programs using reliable and valid outcome measures, as well as study methods which provide higher levels of evidence.

Effect of botulinum toxin A & task-specific training on upper limb function in post-stroke focal dystonia.

OBJECTIVE: To determine the effect of botulinum toxin A and task-specific training on upper limb function in post-stroke focal dystonia patients. METHODS: A randomised control trial was conducted at hospitals in Rawalpindi and Islamabad, Pakistan, from October 2015 to September 2016. The subjects were recruited using non-probability purposive sampling and were divided equally into control and experimental groups by sealed envelope method. The experimental group received botulinum toxin A followed by task-specific training, while the control group received only task-specific training for 8 weeks. Data was collected at baseline, after 4 weeks and 8 weeks by using upper extremity items of Motor Assessment Scale and Fugl-Meyer Assessment scale of upper limb. RESULTS: There were 43 subjects divided into two equal groups of 23(50%) each. In the experimental group, mean age of patients was 43.57±10.94 years while in the control group it was 48.75±10.75 years (p=0.135). There were 15(71.4%) male and 6(28.6%) female patients in the experimental group and 9(45%) were male and 11(55%) were female in the control group. Both groups showed significant improvements on the Motor Assessment Scale and Fugl-Meyer Assessment scale (p<0.01), but no significant differences were observed between the groups at baseline, after 4 and 8 weeks of intervention (p>0.05). CONCLUSIONS: Eight weeks of task-specific training improved upper limb function in post-stroke focal dystonia patients.

Two single cases treated by a new pseudoelastic upper-limb orthosis for secondary dystonia of the young.

The study proposes a new treatment for dystonia based on a dynamic wearable orthosis equipped with metallic materials of non-linear mechanical characteristics. Two boys with upper-limb dystonia were enrolled, as well as six healthy children. Fully-customised devices were made for the patients. They used the orthosis for one month and their performances were evaluated before and after the treatment. The assessment was done with clinical scales (Modified Ashworth Score, Melbourne Upper Limb Assessment, PedsQL), interviews and optoelectronic kinematic analysis. Normal kinematics was obtained from the healthy group for comparison. Kinematic analysis showed modifications in motor patterns for both patients, with increases in the ranges of motion of initially stiff segments, improvements in posture, emergence of multi-joint strategies. Clinical scales did not always show similar trends in the two cases. The changes in control strategies could be linked to the force field dynamically applied by the device and appear to be learnable. This interpretation will be further tested with larger groups and longer treatments.

Complications of Deep Brain Stimulation (DBS) for dystonia in children - The challenges and 10 year experience in a large paediatric cohort.

Deep brain stimulation (DBS) has been increasingly used for primary and secondary movement disorders in children and young people. Reports of hardware related complications have been sparse for this population and from small cohorts of patients. We report DBS complications from a single large DBS centre with 10 year experience. Data was collected as a prospective audit and additionally from a questionnaire on recharging of the stimulators. 129 patients with a minimum 6 months follow up were identified, mean age10.8 y (range 3.0-18.75), mean follow up 3.3y (range 0.5-10.3), weight 10.4-94.2 kg, 126 new implants (92 Activa RC) and 69 revisions for reasons other than infection. 26 patients were 7y or younger. Surgical site infections (SSI) rates were 10.3% for new implants and revisions, lower 8.6% for new Activa RC and even lower, 4.7%, for new Activa RC in patients under 7y (1/21). SSI occurred within first 6 months and necessitated total system removal in 86% of those infected. Electrode/extension problems were recorded in 18.4% of patients, fracture in 4.6% malfunction in 7.7%, short extension 3.8% and electrode migration in 2.3%. Other complications involved clinically silent intracranial bleed in 1 patient, skin erosions (2.3%), unexpected switching off in 18.7% of Soletra/Kinetra and 3.4% of Activa RC, transient seroma at IPG site in postoperative period (8%). Of the 48 returned recharging questionnaires, 38% of families required recharger replacement and 23% experienced frequent problems maintaining connection during recharging. However, 83% of responders considered recharging not at all or only a little care burden. We identified lower than previously reported DBS infection rates particularly for patients under 7 years, but relatively high incidence of technical problems with electrodes, extensions and in particular recharging. This has to be considered when offering DBS for children with movement disorders.

A simple orthosis solves a problem in a patient with a dystonic finger after stroke.

These authors use a custom-fabricated orthotic device to improve hand motion and function for a client with hand dystonia after stroke. Clinical observation and reasoning resulted in an effective solution to control the dystonia that was acceptable to the client. - Kristin Valdes, OTD, OT, CHT, Practice Forum Editor.

What parents think and feel about deep brain stimulation in paediatric secondary dystonia including cerebral palsy: A qualitative study of parental decision-making.

BACKGROUND: Dystonia is characterised by involuntary movements and postures. Deep Brain Stimulation (DBS) is effective in reducing dystonic symptoms in primary dystonia in childhood and to lesser extent in secondary dystonia. How families and children decide to choose DBS surgery has never been explored. AIMS: To explore parental decision-making for DBS in paediatric secondary dystonia. METHODS: Data was gathered using semi-structured interviews with eight parents of children with secondary dystonia who had undergone DBS. Interviews were analysed using Interpretative Phenomenological Analysis. RESULTS: For all parents the decision was viewed as significant, with life altering consequences for the child. These results suggested that parents were motivated by a hope for a better life and parental duty. This was weighed against consideration of risks, what the child had to lose, and uncertainty of DBS outcome. Decisions were also influenced by the perspectives of their child and professionals. CONCLUSIONS: The decision to undergo DBS was an ongoing process for parents, who ultimately were struggling in the face of uncertainty whilst trying to do their best as parents for their children. These findings have important clinical implications given the growing referrals for consideration of DBS childhood dystonia, and highlights the importance of further quantitative research to fully establish the efficacy of DBS in secondary dystonia to enhance informed decision-making.

Scaled Vibratory Feedback Can Bias Muscle Use in Children With Dystonia During a Redundant, 1-Dimensional Myocontrol Task.

Vibratory feedback can be a useful tool for rehabilitation. We examined its use in children with dystonia to understand how it affects muscle activity in a population that does not respond well to standard rehabilitation. We predicted scaled vibration (ie, vibration that was directly or inversely proportional to muscle activity) would increase use of the vibrated muscle because of task-relevant sensory information, whereas nonscaled vibration would not change muscle use. The study was conducted on 11 subjects with dystonia and 14 controls. Each subject underwent 4 different types of vibration on the more dystonic biceps muscle (or nondominant arm in controls) in a 1-dimensional, bimanual myocontrol task. Our results showed that only scaled vibratory feedback could bias muscle use without changing overall performance in children with dystonia. We believe there may be a role in rehabilitation for scaled vibratory feedback to retrain abnormal muscle patterns.

German registry of paediatric deep brain stimulation in patients with childhood-onset dystonia (GEPESTIM).

BACKGROUND: Data on paediatric deep brain stimulation (DBS) is limited, especially for long-term outcomes, because of small numbers in single center series and lack of systematic multi-center trials. OBJECTIVES: We seek to systematically evaluate the clinical outcome of paediatric patients undergoing DBS. METHODS: A German registry on paediatric DBS (GEPESTIM) was created to collect data of patients with dystonia undergoing DBS up to the age of 18 years. Patients were divided into three groups according to etiology (group 1 inherited, group 2 acquired, and group 3 idiopathic dystonia). RESULTS: Data of 44 patients with a mean age of 12.8 years at time of operation provided by 6 German centers could be documented in the registry so far (group 1 n = 18, group 2 n = 16, group 3 n = 10). Average absolute improvement after implantation was 15.5 ± 18.0 for 27 patients with pre- and postoperative Burke-Fahn-Marsden Dystonia Rating scale movement scores available (p < 0.001) (group 1: 19.6 ± 19.7, n = 12; group 2: 7.0 ± 8.9, n = 8; group 3: 19.2 ± 20.7, n = 7). Infection was the main reason for hardware removal (n = 6). 20 IPG replacements due to battery expiry were necessary in 15 patients at 3.7 ± 1.8 years after last implantation. DISCUSSION: Pre- and postoperative data on paediatric DBS are very heterogeneous and incomplete but corroborate the positive effects of DBS on inherited and acquired dystonia. Adverse events including relatively frequent IPG replacements due to battery expiry seem to be a prominent feature of children with dystonia undergoing DBS. The registry enables collaborative research on DBS treatment in the paediatric population and to create standardized management algorithms in the future.

Stable cognitive functioning with improved perceptual reasoning in children with dyskinetic cerebral palsy and other secondary dystonias after deep brain stimulation.

BACKGROUND: Dystonia is characterised by involuntary movements (twisting, writhing and jerking) and postures. Secondary dystonias are described as a heterogeneous group of disorders with both exogenous and endogenous causes. There is a growing body of literature on the effects of deep brain stimulation (DBS) surgery on the motor function in childhood secondary dystonias, however research on cognitive function after DBS is scarce. METHODS: Cognitive function was measured in a cohort of 40 children with secondary dystonia following DBS surgery using a retrospective repeated measures design. Baseline pre-DBS neuropsychological measures were compared to scores obtained at least one year following DBS. Cognitive function was assessed using standardised measures of intellectual ability and memory. RESULTS: There was no significant change in the assessed domains of cognitive function following DBS surgery. A significant improvement across the group was found on the Picture Completion subtest, measuring perceptual reasoning ability, following DBS. CONCLUSION: Cognition remained stable in children with secondary dystonia following DBS surgery, with some improvements noted in a domain of perceptual reasoning. Further research with a larger sample is necessary to further explore this, in particular to further subdivide this group to account for its heterogeneity. This preliminary data has potentially positive implications for the impact of DBS on cognitive functioning within the childhood secondary dystonia population.

Differences in active range of motion measurements in the upper extremity of patients with writer's cramp compared with healthy controls.

STUDY DESIGN: Exploratory case-control study. INTRODUCTION: Writer's cramp (WC) is a type of focal hand dystonia. The central nervous system plays a role in its pathophysiology, but abnormalities in the affected musculoskeletal components may also be relevant. PURPOSE OF THE STUDY: We compared the active range of motion (ROM) in patients with WC and healthy volunteers (HVs) and correlated the findings with disease duration and severity. METHODS: Affected limb joints were measured with goniometers. Patients were assessed at least 3 months after their last botulinum toxin (botulinum neurotoxin) injection, and strength was clinically normal. t tests were used to compare the ROMs of WC with matched HVs. The Spearman correlation coefficient assessed the relationship of active ROMs to the disease duration and handwriting subscore of the Dystonia Disability Scale. RESULTS: ROMs of D1 metacarpophalangeal (MCP) joint extension as well as D2 and D5 MCP flexion were significantly smaller in WC, and distal interphalangeal joint extension in D3 and D5 was significantly greater compared with HVs. There were negative correlations between D2 MCP flexion and disease duration and with Dystonia Disability Scale. DISCUSSION: Abnormalities in ROMs in WC were found. Severity and disease duration correlated with reduced D2 MCP flexion. This may be related to intrinsic biomechanical abnormalities, co-contraction of muscles, or a combination of subclinical weakness and atrophy from repeated botulinum neurotoxin injections. CONCLUSIONS: Hand biomechanical properties should not be ignored in the pathophysiology of WC. LEVEL OF EVIDENCE: 2c.

Haptic Feedback Manipulation During Botulinum Toxin Injection Therapy for Focal Hand Dystonia Patients: A Possible New Assistive Strategy.

Abnormality of sensorimotor integration in the basal ganglia and cortex has been reported in the literature for patients with task-specific focal hand dystonia (FHD). In this study, we investigate the effect of manipulation of kinesthetic input in people living with writer's cramp disorder (a major form of FHD). For this purpose, severity of dystonia is studied for 11 participants while the symptoms of seven participants have been tracked during five sessions of assessment and Botulinum toxin injection (BoNT-A) therapy (one of the current suggested therapies for dystonia). BoNT-A therapy is delivered in the first and the third session. The goal is to analyze the effect of haptic manipulation as a potential assistive technique during BoNT-A therapy. The trial includes writing, hovering, and spiral/sinusoidal drawing subtasks. In each session, the subtasks are repeated twice when (a) a participant uses a normal pen, and (b) when the participant uses a robotics-assisted system (supporting the pen) which provides a compliant virtual writing surface and manipulates the kinesthetic sensory input. The results show (p-value using one-sample t-tests) that reducing the writing surface rigidity significantly decreases the severity of dystonia and results in better control of grip pressure (an indicator of dystonic cramping). It is also shown that (p-value based on paired-samples t-test) using the proposed haptic manipulation strategy, it is possible to augment the effectiveness of BoNT-A therapy. The outcome of this study is then used in the design of an actuated pen as a writing-assistance tool that can provide compliant haptic interaction during writing for FHD patients.

Combinación de tres técnicas en el reentrenamiento de un músico con distonía focal: estudio de un caso / The use of three combined techniques in the retraining of a mucisian with focal dystonia: a case study

La distonía resulta de una co-contracción sostenida de músculos agonistas y antagonistas que puede causar torsión, movimientos involuntarios o posturas anormales que interfieren con el control voluntario de la mano, u otro grupo muscular, involucrados en una determinada acción; por ejemplo, tocar un instrumento, o escribir.El presente estudio descriptivo, de caso único, buscó probar la efectividad de un tratamiento que combinó tres técnicas (técnica del umbral, imaginería, y relajación por neurofeedback) en el reentrenamiento de un concertista profesional con distonía focal. Según evaluación por jueces, los resultados después de dos semanas de tratamiento, no fueron concluyentes. Sin embargo, el reporte experiencial del propio músico dio cuenta de una clara mejoría. Ante la carencia de un método efectivo para larehabilitación demúsicos con distonía focal, la relevancia del presente estudio consistió en identificar y combinar técnicas específicas que pueden contribuir a ese propósito. En estudios futuros, sería de interés probar el efecto del mismo tratamiento,pero más prolongado; o el efecto de la incorporación de las técnicas en sucesión progresiva, iniciando siempre con la relajación por neurofeedback.

Focal dystonia results from a sustained simultaneous co-contraction of agonists and antagonists muscle fibers which can cause twisting, involuntary movements or abnormal postures that interfere with voluntary control of the hand, arm, mouth, or other muscle groups involved in a given action; for example, playing an instrument, or hand writing. This descriptive, single case study, sought to explore the effectiveness of a treatment that combined three procedures: the threshold technique, imagery, and neurofeedback induced relaxation, in retraining of a professional cello player with focal dystonia. After two weeks of treatment, experts judged the results inconclusive; however, the report from the actual patient accounted for a note worthy recovery over time. In the absence of an effective method to rehabilitate musicians with focal dystonia, the relevance of this study resided on thepossibility of identifying and combining specific techniques that could be effective. Future studies might want to explore these same or different techniques, but perhaps for a longer period of time.

Acquisition and reacquisition of motor coordination in musicians.

Precise control of movement timing plays a key role in musical performance. This motor skill requires coordination across multiple joints and muscles, which is acquired through extensive musical training from childhood. However, extensive training has a potential risk of causing neurological disorders that impair fine motor control, such as task-specific tremor and focal dystonia. Recent technological advances in measurement and analysis of biological data, as well as noninvasive manipulation of neuronal activities, have promoted the understanding of computational and neurophysiological mechanisms underlying acquisition, loss, and reacquisition of dexterous movements through musical practice and rehabilitation. This paper aims to provide an overview of the behavioral and neurophysiological basis of motor virtuosity and disorder in musicians, representative extremes of human motor skill. We also report novel evidence of effects of noninvasive neurorehabilitation that combined transcranial direct-current stimulation and motor rehabilitation over multiple days on musician's dystonia, which offers a promising therapeutic means.

Focal hand dystonia: individualized intervention with repeated application of repetitive transcranial magnetic stimulation.

OBJECTIVES: To examine for individual factors that may predict response to inhibitory repetitive transcranial magnetic stimulation (rTMS) in focal hand dystonia (FHD); to present the method for determining optimal stimulation to increase inhibition in a given patient; and to examine individual responses to prolonged intervention. DESIGN: Single-subject design to determine optimal parameters to increase inhibition for a given subject and to use the selected parameters once per week for 6 weeks, with 1-week follow-up, to determine response. SETTING: Clinical research laboratory. PARTICIPANTS: A volunteer sample of subjects with FHD (N = 2). One participant had transcranial magnetic stimulation responses indicating impaired inhibition, and the other had responses within normative limits. INTERVENTIONS: There were 1200 pulses of 1-Hz rTMS delivered using 4 different stimulation sites/intensity combinations: primary motor cortex at 90% or 110% of resting motor threshold (RMT) and dorsal premotor cortex (PMd) at 90% or 110% of RMT. The parameters producing the greatest within-session increase in cortical silent period (CSP) duration were then used as the intervention. MAIN OUTCOME MEASURES: Response variables included handwriting pressure and velocity, subjective symptom rating, CSP, and short latency intracortical inhibition and facilitation. RESULTS: The individual with baseline transcranial magnetic stimulation responses indicating impaired inhibition responded favorably to the repeated intervention, with reduced handwriting force, an increase in the CSP, and subjective report of moderate symptom improvement at 1-week follow-up. The individual with normative baseline responses failed to respond to the intervention. In both subjects, 90% of RMT to the PMd produced the greatest lengthening of the CSP and was used as the intervention. CONCLUSIONS: An individualized understanding of neurophysiological measures can be an indicator of responsiveness to inhibitory rTMS in focal dystonia, with further work needed to determine likely responders versus nonresponders.

A multifactorial conceptual model of peripheral neuromusculoskeletal predisposing factors in task-specific focal hand dystonia in musicians: etiologic and therapeutic implications.

A model is presented showing how peripheral factors may cause a process of movement adaptation that leads to task-specific focal hand dystonia in musicians (FHDM). To acquire a playing technique, the hand must find effective and physiologically sustainable movements within a complex set of functional demands and anatomic, ergonomic, and physiological constraints. In doing so, individually discriminating constraints may become effective, such as limited anatomic independence of finger muscles/tendons, limited joint ranges of motion, or (subclinical) neuromusculoskeletal defects. These factors may, depending on the instrument-specific playing requirements, compromise or exclude functional playing movements. The controller (i.e., the brain) then needs to develop alternative motions to execute the task, which is called compensation. We hypothesize that, if this compensation process does not converge to physiologically sustainable muscle activation patterns that satisfy all constraints, compensation could increase indefinitely under the pressure of practice. Dystonic symptoms would become manifest when overcompensation occurs, resulting in motor patterns that fail in proper task execution. The model presented in this paper only concerns the compensatory processes preceding such overcompensations and does not aim to explain the nature of the dystonic motions themselves. While the model considers normal learning processes in the development of compensations, neurological predispositions could facilitate developing overcompensations or further abnormal motor programs. The model predicts that if peripheral factors are involved, FHDM symptoms would be preceded by long-term gradual changes in playing movements, which could be validated by prospective studies. Furthermore, the model implies that treatment success might be enhanced by addressing the conflict between peripheral factors and playing tasks before decompensating/retraining the affected movements.