Repetitive exercise dystonia: A difficult to treat hazard of runner and non-runner athletes

The Relationship Between Stiff Knee Gait Runner's Dystonia and Musculoskeletal Knee Pathology: A Case Series

BACKGROUND

Runner's dystonia (RD), a rare task-specific lower-limb dystonia affecting high-mileage runners, presents as abnormal lower-extremity muscle contractions during running. Treatment of RD is challenging and often confounded by significant diagnostic delays due to overlapping symptomatology with other conditions. This case series examines the relationship between stiff knee gait RD and musculoskeletal (MSK) knee pathology.

METHODS

Eight RD cases, evaluated at the NIH Movement Disorders Clinic since 2018, were retrospectively reviewed. Patients underwent neurological, biomechanical, and MSK evaluations, including 3D motion analysis, surface electromyography, and knee ultrasound. Therapeutic interventions, including botulinum neurotoxin (BoNT) injections, were assessed.

RESULTS

Seven patients demonstrated stiff knee gait subtypes, with all having ipsilateral and/or contralateral knee effusions or tendinopathies. Three patients who received MSK interventions (e.g., aspiration, corticosteroid injections) combined with BoNT therapy experienced significant symptom improvement. One patient with isolated foot dystonia displayed different biomechanical patterns without knee pathology.

CONCLUSIONS

RD patients with stiff knee gait often exhibit knee pathology, most likely due to altered biomechanics and running history. Addressing both issues is essential for optimizing treatment outcomes, reducing pain, and improving function, especially since pain can trigger dystonia. Future research should determine the ideal sequence of interventions for RD patients with MSK issues to develop effective, personalized treatment algorithms.

Muscular and kinematic features in speed skaters indicate a task-specific dystonia

OBJECTIVE

Skater's cramp is a movement disorder in speed skaters. We investigated whether affected skaters matched the disease profile of task-specific dystonia, specifically whether there was evidence of maladaptive muscle activity occurring simultaneously with aberrant movements (jerking). We further examined different skating intensities, positing no change would be more indicative of task-specific dystonia.

METHODS

We analyzed video, kinematic and muscle activity in 14 affected skaters. We measured the angular velocity and electromyographic activity of normalized speed skating strokes using one dimensional statistical non-parametric mapping. Skaters were matched with comparably skilled controls, and filled out a bespoke clinical questionnaire.

RESULTS

Skaters' impacted leg showed over-activation in the peroneus longus, tibialis anterior and gastrocnemius that coincided with higher foot movement compared to their healthy leg and controls. This pattern persisted regardless of skating intensity. Clinical features indicated it was task-specific and painless with common trigger factors including stress, equipment change, and falling.

CONCLUSIONS

We showed aberrant muscular and kinematic activity in a movement disorder in speed skaters indicative of task-specific dystonia.

SIGNIFICANCE

Understanding skater's cramp as a task-specific dystonia could reduce the damage that misdiagnosis and unsuccessful invasive operations have caused. Our quantitative method has value in testing future treatment efficacy.

The Dystonias

PURPOSE OF REVIEW

This article discusses the most recent findings regarding the diagnosis, classification, and management of genetic and idiopathic dystonia.

RECENT FINDINGS

A new approach to classifying dystonia has been created with the aim to increase the recognition and diagnosis of dystonia. Molecular biology and genetic studies have identified several genes and biological pathways involved in dystonia.

SUMMARY

Dystonia is a common movement disorder involving abnormal, often twisting, postures and is a challenging condition to diagnose. The pathophysiology of dystonia involves abnormalities in brain motor networks in the context of genetic factors. Dystonia has genetic, idiopathic, and acquired forms, with a wide phenotypic spectrum, and is a common feature in complex neurologic disorders. Dystonia can be isolated or combined with another movement disorder and may be focal, segmental, multifocal, or generalized in distribution, with some forms only occurring during the performance of specific tasks (task-specific dystonia). Dystonia is classified by clinical characteristics and presumed etiology. The management of dystonia involves accurate diagnosis, followed by treatment with botulinum toxin injections, oral medications, and surgical therapies (mainly deep brain stimulation), as well as pathogenesis-directed treatments, including the prospect of disease-modifying or gene therapies.

Sports-Related Dystonia

Background

Task-specific dystonia (TSD) is a form of focal dystonia that occurs in the context of the performance of selective, highly skilled, often repetitive, motor activity. TSD may be apparent during certain tasks such as writing, playing musical instruments, or other activities requiring fine motor control, but may also occur during certain sports, and maybe detrimental to professional athletes' careers. Therefore, sports physicians and movement disorder neurologists need to be aware of the presentation and phenomenology of sports-related dystonia (SRD), the topic of this review.

Methods

A broad PubMed search using a wide range of keywords and combinations was done in October 2021 to identify suitable articles for this review.

Results

Most of the publications are on yips in golfers and on runners' dystonia. Other sports in which SRD has been reported are ice skating, tennis, table tennis, pistol shooting, petanque, baseball, and billiards.

Discussion

Yips, which may affect up to half of the golfers and rarely athletes in other sports (e.g., baseball, cricket, basketball, speed skating, gymnastics) seems to be a multi-factorial form of TSD that is particularly troublesome in highly skilled professional golfers. Runners' dystonia, affecting the foot, leg, and hip (in decreasing order), may evolve into more generalized and less specific dystonia. The pathophysiologic mechanisms of SRD are not well understood. Botulinum toxin has been reported to alleviate dystonia in golfers', runners', and other forms of SRD. Future studies should utilize neurophysiologic, imaging, and other techniques to elucidate mechanisms of this underrecognized group of movement disorders.

Symptom Locus and Symptom Origin Incongruity in Runner's Dystonia - Case Study of an Elite Female Runner

Objectives: Runner's dystonia is a task-specific dystonia that occurs in the lower limbs and trunk, with diverse symptomatology. We aimed to identify the origin of a dystonic movement abnormality using combined three-dimensional kinematic analysis and electromyographic (EMG) assessment during treadmill running. Participant: A 20-year-old female runner who complained of right-foot collision with the left-leg during right-leg swing-phase, which mimicked right-ankle focal dystonia. Results: Kinematic and EMG assessment of her running motion was performed, which showed a significant drop of the left pelvis during right-leg stance-phase, and a simultaneous increase of right hip adductor muscle activity. This resulted in a pronounced adduction of the entire right lower limb with respect to the pelvis segment. Trajectories of right foot were seen to encroach upon left-leg area. Discussion: These findings suggested that the symptom of this runner was most likely a form of segmental dystonia originating from an impaired control of hip and pelvis, rather than a distal focal ankle dystonia. Conclusion: We conclude that, for individualized symptom assessment, deconstructing the symptom origin from its secondary compensatory movement is crucial for characterizing dystonia. Kinematic and EMG evaluation will therefore be a prerequisite to distinguish symptom origin from secondary compensatory movement.

Second hit hypothesis in dystonia: Dysfunctional cross talk between neuroplasticity and environment?

One of the great mysteries in dystonia pathophysiology is the role of environmental factors in disease onset and development. Progress has been made in defining the genetic components of dystonic syndromes, still the mechanisms behind the discrepant relationship between dystonic genotype and phenotype remain largely unclear. Within this review, the preclinical and clinical evidence for environmental stressors as disease modifiers in dystonia pathogenesis are summarized and critically evaluated. The potential role of extragenetic factors is discussed in monogenic as well as adult-onset isolated dystonia. The available clinical evidence for a "second hit" is analyzed in light of the reduced penetrance of monogenic dystonic syndromes and put into context with evidence from animal and cellular models. The contradictory studies on adult-onset dystonia are discussed in detail and backed up by evidence from animal models. Taken together, there is clear evidence of a gene-environment interaction in dystonia, which should be considered in the continued quest to unravel dystonia pathophysiology.

Electromyographic and Joint Kinematic Patterns in Runner's Dystonia

Runner’s dystonia (RD) is a task-specific focal dystonia of the lower limbs that occurs when running. In this retrospective case series, we present surface electromyography (EMG) and joint kinematic data from thirteen patients with RD who underwent instrumented gait analysis (IGA) at the Functional and Biomechanics Laboratory at the National Institutes of Health. Four cases of RD are described in greater detail to demonstrate the potential utility of EMG with kinematic studies to identify dystonic muscle groups in RD. In these cases, the methodology for muscle selection for botulinum toxin therapy and the therapeutic response is discussed. Lateral heel whip, a proposed novel presentation of lower-limb dystonia, is also described.

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.

Neurologic Injuries in Noncontact Sports

Noncontact sports are associated with a variety of neurologic injuries. Concussion, vascular injury (arterial dissection), and spinal cord trauma may be less common in noncontact sports, but require special attention from the sports neurologist. Complex regional pain disorders, muscle injury from repetitive use, dystonia, heat exposure, and vascular disorders (patent foramen ovale), occur with similar frequency in noncontact and contact sports. Management of athletes with these conditions requires an understanding of the neurologic consequences of these disorders, the risk of injury with return to play, and consideration for the benefits of exercise in health restoration and disease prevention.

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.