Peripheral trauma induced dystonia or post-traumatic syndrome?

Disturbed brain energy metabolism in a rodent model of DYT-TOR1A dystonia

DYT-TOR1A (DYT1) dystonia, characterized by reduced penetrance and suspected environmental triggers, is explored using a "second hit" DYT-TOR1A rat model. We aim to investigate the biological mechanisms driving the conversion into a dystonic phenotype, focusing on the striatum's role in dystonia pathophysiology. Sciatic nerve crush injury was induced in ∆ETorA rats, lacking spontaneous motor abnormalities, and wild-type (wt) rats. Twelve weeks post-injury, unbiased RNA-sequencing was performed on the striatum to identify differentially expressed genes (DEGs) and pathways. Fenofibrate, a PPARα agonist, was introduced to assess its effects on gene expression. 18F-FDG autoradiography explored metabolic alterations in brain networks. Low transcriptomic variability existed between naïve wt and ∆ETorA rats (17 DEGs). Sciatic nerve injury significantly impacted ∆ETorA rats (1009 DEGs) compared to wt rats (216 DEGs). Pathway analyses revealed disruptions in energy metabolism, specifically in fatty acid β-oxidation and glucose metabolism. Fenofibrate induced gene expression changes in wt rats but failed in ∆ETorA rats. Fenofibrate increased dystonia-like movements in wt rats but reduced them in ∆ETorA rats. 18F-FDG autoradiography indicated modified glucose metabolism in motor and somatosensory cortices and striatum in both ∆ETorA and wt rats post-injury. Our findings highlight perturbed energy metabolism pathways in DYT-TOR1A dystonia, emphasizing compromised PPARα agonist efficacy in the striatum. Furthermore, we identify impaired glucose metabolism in the brain network, suggesting a potential shift in energy substrate utilization in dystonic DYT-TOR1A rats. These results contribute to understanding the pathophysiology and potential therapeutic targets for DYT-TOR1A dystonia.

Multimodal Care of a Patient With Functional Movement Disorders Following a Motor Vehicle Accident: A Case Report

Objective

The purpose of this case report was to describe the multimodal care of a patient with the sudden onset of truncal tremors.

Clinical Features

A 30-year-old female patient presented for chiropractic care with truncal tremors following a motor vehicle accident. Initial outcome measures included the Neck Disability Index (50%) and Oswestry Disability Index (62). The patient's truncal tremors became worse during spinal cord compression testing that included passive cervical flexion and slouched posture. The Romberg test was positive for swaying. Assessments of active range of motions of the cervical, thoracic, and lumbar spine were moderately reduced in all ranges. Case history, physical examinations, diagnostic imaging, and neurology consultations led to a diagnosis of functional truncal tremors. The patient was being concurrently managed by other health care providers. Magnetic resonance imaging studies were ordered by a neurologist and primary medical physician, which showed no structural abnormalities in brain neuroanatomy or spine.

Intervention and Outcome

The multimodal chiropractic care included whole-body vibration therapy (WBVT), spinal manipulative therapy (SMT), and acupuncture therapy. The treatment plan included 8 weekly appointments in which the patient received WBVT and SMT. During treatment weeks 2 to 6, the patient received acupuncture therapy, which occurred immediately following their treatment appointment for WBVT and SMT. The patient practiced stress reduction techniques, as advised by the neurologist, eliminated caffeine, and performed daily yoga exercises for 30 minutes. The Romberg test was negative after the third treatment. The patient was discharged after chiropractic visit 12, 95 days post-accident, as she reached maximal medical improvement. Truncal tremors were still present, but the patient described them as "barely noticeable."

Conclusion

The patient reported improvement under a course of chiropractic care using a multimodal approach, including behavioral, pharmacological, and manual therapies. This case study suggests that WBVT, SMT, and acupuncture therapy may assist some patients with functional movement disorders.

Peripherally-induced Movement Disorders: An Update

Background

Peripherally-induced movement disorders (PIMD) should be considered when involuntary or abnormal movements emerge shortly after an injury to a body part. A close topographic and temporal association between peripheral injury and onset of the movement disorders is crucial to diagnosing PIMD. PIMD is under-recognized and often misdiagnosed as functional movement disorder, although both may co-exist. Given the considerable diagnostic, therapeutic, and psychosocial-legal challenges associated with PIMD, it is crucial to update the clinical and scientific information about this important movement disorder.

Methods

A comprehensive PubMed search through a broad range of keywords and combinations was performed in February 2023 to identify relevant articles for this narrative review.

Results

The spectrum of the phenomenology of PIMD is broad and it encompasses both hyperkinetic and hypokinetic movements. Hemifacial spasm is probably the most common PIMD. Others include dystonia, tremor, parkinsonism, myoclonus, painful leg moving toe syndrome, tics, polyminimyoclonus, and amputation stump dyskinesia. We also highlight conditions such as neuropathic tremor, pseudoathetosis, and MYBPC1-associated myogenic tremor as examples of PIMD.

Discussion

There is considerable heterogeneity among PIMD in terms of severity and nature of injury, natural course, association with pain, and response to treatment. As some patients may have co-existing functional movement disorder, neurologists should be able to differentiate the two disorders. While the exact pathophysiology remains elusive, aberrant central sensitization after peripheral stimuli and maladaptive plasticity in the sensorimotor cortex, on a background of genetic (two-hit hypothesis) or other predisposition, seem to play a role in the pathogenesis of PIMD.

Experimental deep brain stimulation in rodent models of movement disorders

Deep brain stimulation (DBS) is the preferred treatment for therapy-resistant movement disorders such as dystonia and Parkinson's disease (PD), mostly in advanced disease stages. Although DBS is already in clinical use for ~30 years and has improved patients' quality of life dramatically, there is still limited understanding of the underlying mechanisms of action. Rodent models of PD and dystonia are essential tools to elucidate the mode of action of DBS on behavioral and multiscale neurobiological levels. Advances have been made in identifying DBS effects on the central motor network, neuroprotection and neuroinflammation in DBS studies of PD rodent models. The phenotypic dt^sz mutant hamster and the transgenic DYT-TOR1A (ΔETorA) rat proved as valuable models of dystonia for preclinical DBS research. In addition, continuous refinements of rodent DBS technologies are ongoing and have contributed to improvement of experimental quality. We here review the currently existing literature on experimental DBS in PD and dystonia models regarding the choice of models, experimental design, neurobiological readouts, as well as methodological implications. Moreover, we provide an overview of the technical stage of existing DBS devices for use in rodent studies.

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.

The evolution of dystonia-like movements in TOR1A rats after transient nerve injury is accompanied by dopaminergic dysregulation and abnormal oscillatory activity of a central motor network

TOR1A is the most common inherited form of dystonia with still unclear pathophysiology and reduced penetrance of 30-40%. ∆ETorA rats mimic the TOR1A disease by expression of the human TOR1A mutation without presenting a dystonic phenotype. We aimed to induce dystonia-like symptoms in male ∆ETorA rats by peripheral nerve injury and to identify central mechanism of dystonia development. Dystonia-like movements (DLM) were assessed using the tail suspension test and implementing a pipeline of deep learning applications. Neuron numbers of striatal parvalbumin⁺, nNOS⁺, calretinin⁺, ChAT⁺ interneurons and Nissl⁺ cells were estimated by unbiased stereology. Striatal dopaminergic metabolism was analyzed via in vivo microdialysis, qPCR and western blot. Local field potentials (LFP) were recorded from the central motor network. Deep brain stimulation (DBS) of the entopeduncular nucleus (EP) was performed. Nerve-injured ∆ETorA rats developed long-lasting DLM over 12 weeks. No changes in striatal structure were observed. Dystonic-like ∆ETorA rats presented a higher striatal dopaminergic turnover and stimulus-induced elevation of dopamine efflux compared to the control groups. Higher LFP theta power in the EP of dystonic-like ∆ETorA compared to wt rats was recorded. Chronic EP-DBS over 3 weeks led to improvement of DLM. Our data emphasizes the role of environmental factors in TOR1A symptomatogenesis. LFP analyses indicate that the pathologically enhanced theta power is a physiomarker of DLM. This TOR1A model replicates key features of the human TOR1A pathology on multiple biological levels and is therefore suited for further analysis of dystonia pathomechanism.

Models of dystonia: an update

Although dystonia represents the third most common movement disorder, its pathophysiology remains still poorly understood. In the past two decades, multiple models have been generated, improving our knowledge on the molecular and cellular bases of this heterogeneous group of movement disorders. In this short survey, we will focus on recently generated novel models of DYT1 dystonia, the most common form of genetic, "isolated" dystonia. These models clearly indicate the existence of multiple signaling pathways affected by the protein mutation causative of DYT1 dystonia, torsinA, paving the way for potentially multiple, novel targets for pharmacological intervention.

Focal Neuropathy Mimicking Focal Dystonia in a Child: Diagnostic and Rehabilitative Tools

OBJECT

Focal neuropathy results from an injury of any etiology that occurs in a peripheral nerve. The lesion may be followed by alteration of the sensory sphere (either dysesthesia or paresthesia with or without neuropathic pain), or by compensatory attitudes that are attributable to the altered contraction in muscles that are innervated by the injured nerve.

METHODS

We describe the case of a 13-year-old boy who attended our hospital for a focal neuropathy of the radial nerve.

CONCLUSION

This neuropathy was revealed after the removal of a plaster Zimmer splint that was applied following a post-traumatic subluxation of the metacarpal-trapezoid joint.

Pseudodystonia: A new perspective on an old phenomenon

Pseudodystonia represents a wide range of conditions that mimic dystonia, including disorders of the peripheral nervous system, spinal cord, brainstem, thalamus, cortex and non-neurological conditions such as musculoskeletal diseases. Here, we propose a definition of pseudodystonia and suggest a classification based on underlying pathophysiological mechanisms. We describe phenomenology of different forms of pseudodystonia and point to distinctions between dystonia and pseudodystonia as well as challenging issues that may arise in clinical practice. The term pseudodystonia can be used to describe abnormal postures, repetitive movements or both, in which results of clinical, imaging, laboratory or electrophysiological investigations provide definite explanation of symptoms which is not compatible with dystonia. Pseudodystonia can be classified into non-neurological disorders of the musculoskeletal system, disorders of sensory pathways, disorders of motor pathways and compensatory postures in other neurological diseases. Presence of associated neurological findings in the affected body part is the key towards diagnosis of pseudodystonia. Additional supporting features are the presence of fixed postures, the absence of sensory trick, acute mode of onset and severe pain. Worsening on eye closure, traditionally considered typical for pseudodystonia, is not always present and can also appear in dystonia. It is challenging to separate dystonia and pseudodystonia in patients with thalamic lesions or corticobasal syndrome, where abnormal postures coexist with sensory loss. Many cases of pseudodystonia are treatable. Therefore, it is essential to consider pseudodystonia in a differential diagnosis of abnormal postures until a detailed neurological examination rules it out.

Tor1a+/- mice develop dystonia-like movements via a striatal dopaminergic dysregulation triggered by peripheral nerve injury

Isolated generalized dystonia is a central motor network disorder characterized by twisted movements or postures. The most frequent genetic cause is a GAG deletion in the Tor1a (DYT1) gene encoding torsinA with a reduced penetrance of 30-40 % suggesting additional genetic or environmental modifiers. Development of dystonia-like movements after a standardized peripheral nerve crush lesion in wild type (wt) and Tor1a+/- mice, that express 50 % torsinA only, was assessed by scoring of hindlimb movements during tail suspension, by rotarod testing and by computer-assisted gait analysis. Western blot analysis was performed for dopamine transporter (DAT), D1 and D2 receptors from striatal and quantitative RT-PCR analysis for DAT from midbrain dissections. Autoradiography was used to assess the functional DAT binding in striatum. Striatal dopamine and its metabolites were analyzed by high performance liquid chromatography. After nerve crush injury, we found abnormal posturing in the lesioned hindlimb of both mutant and wt mice indicating the profound influence of the nerve lesion (15x vs. 12x relative to control) resembling human peripheral pseudodystonia. In mutant mice the phenotypic abnormalities were increased by about 40 % (p < 0.05). This was accompanied by complex alterations of striatal dopamine homeostasis. Pharmacological blockade of dopamine synthesis reduced severity of dystonia-like movements, whereas treatment with L-Dopa aggravated these but only in mutant mice suggesting a DYT1 related central component relevant to the development of abnormal involuntary movements. Our findings suggest that upon peripheral nerve injury reduced torsinA concentration and environmental stressors may act in concert in causing the central motor network dysfunction of DYT1 dystonia.

Sensory aspects of movement disorders

Movement disorders, which include disorders such as Parkinson's disease, dystonia, Tourette's syndrome, restless legs syndrome, and akathisia, have traditionally been considered to be disorders of impaired motor control resulting predominantly from dysfunction of the basal ganglia. This notion has been revised largely because of increasing recognition of associated behavioural, psychiatric, autonomic, and other non-motor symptoms. The sensory aspects of movement disorders include intrinsic sensory abnormalities and the effects of external sensory input on the underlying motor abnormality. The basal ganglia, cerebellum, thalamus, and their connections, coupled with altered sensory input, seem to play a key part in abnormal sensorimotor integration. However, more investigation into the phenomenology and physiological basis of sensory abnormalities, and about the role of the basal ganglia, cerebellum, and related structures in somatosensory processing, and its effect on motor control, is needed.

Epidemiologic Advances in Spasmodic Dysphonia

Recently research offers new insights into the pathogenesis, pathophysiology, and socioemotional implications of spasmodic dysphonia (SD). Among these advances are epidemiologic studies clarifying (1) SD onset and course, (2) SD risk factors, and (3) the relationships among SD course, treatment, and psychosocial impact. In this paper, I will provide a summary of recent epidemiologic and socioemotional research advances involving the onset, course, risk factors, and psychosocial impact of SD.

Diagnosis of primary task-specific lower extremity dystonia in a runner

STUDY DESIGN

Resident's case problem.

BACKGROUND

A 56-year-old man was referred to physical therapy for analysis of unusual gait, first noticed 3 years previously when running. Prior to this evaluation, the patient had seen multiple orthopaedic, sports medicine, and neurological specialists while undergoing repeated and extensive testing. Ten months of testing and treatment, including conservative and surgical management, did not provide an explanation for the gait abnormality or result in improvement of the patient's condition.

DIAGNOSIS

The patient's physical examination was relatively unremarkable, considering the severity of the gait abnormality. Distinct abnormalities were apparent with computerized gait analysis and dynamic electromyography, and, when combined with the physical examination findings, led to a suspicion of the task-specific disorder of runner's dystonia. The patient was referred to a neurologist specializing in movement-related disorders, with a final confirmed diagnosis of primary task-specific dystonia with first onset during running (ie, runner's dystonia).

DISCUSSION

Idiopathic, task-specific dystonia of the lower extremity is documented as a very rare occurrence, yet increasing trends in running participation may result in a higher incidence of this condition. Improved awareness of runner's dystonia in the present case might have enhanced the clinical decision-making process and resulted in more timely and effective treatment solutions. Clinical examination findings, including computerized gait analysis and electromyography, in conjunction with imaging, blood, and genetic testing, can aid in the diagnosis of runner's dystonia.

LEVEL OF EVIDENCE

Differential diagnosis, level 4.

Posttraumatic focal dystonia of the shoulder

Focal posttraumatic shoulder dystonia is a rare and not easily identifiable entity. Its true pathophysiologic nature, predisposing factors, and disease course remain debatable.This article describes a rare case of a 40-year-old man with late symptoms of focal shoulder dystonia after peripheral trauma of his left shoulder girdle. The shoulder was indirectly injured from the impact of a fall off his motorbike 3 years earlier. He was referred to the authors' institution because remarkable reduction of arm abduction, muscle spasms, and circumscribed hypertrophy of the trapezius muscle were noted while his head and neck were in neutral position and had a full range of motion. The left shoulder had a fixed elevated posture compared with the contralateral shoulder. A continuous burning pain was localized over the area of the hypertrophied trapezius muscle, radiating to the ipsilateral side of the head and neck. Dystonic movements of the trapezius, rhomboid, and supraspinatus muscles were observed. The abduction of the shoulder was significantly decreased, and any repetitive effort for arm abduction induced an exaggeration of his movement disorder, leading to a more pronounced shoulder elevation.Plain radiographs and magnetic resonance imaging of the left shoulder revealed a suprascapular tendinitis with no other abnormalities. Repeated needle electromyography of the left trapezius muscle and neurography of the accessory nerve on both sides were normal. Injections of botulinum toxin A were effective in the resolution of muscle hypertrophy and abnormal posture.

Patient perceptions of factors leading to spasmodic dysphonia: a combined clinical experience of 350 patients

PURPOSE

Spasmodic dysphonia (SD) is an idiopathic voice disorder that is characterized by either a strained, strangled voice quality or a breathy voice with aphonic segments of connected speech. It has been suggested that environmental factors play a role in triggering the onset. Clinical observation suggests that some patients associate onset with specific events or factors while others do not. The purpose of this study was to examine a large database of SD patients to determine if specific triggers are associated with the onset of SD.

PROCEDURES

Retrospective chart review.

RESULTS

A total of 350 charts of patients with SD were identified and were categorized as either "sudden onset" or "gradual onset." One hundred sixty-nine recalled their circumstances surrounding onset. Forty-five percent of these patients described the onset as sudden. Patient perceptions of inciting events in the sudden onset group were identified 77% of the time and 2% of the time in the gradual onset group. The most common factors identified were stress (42%), upper respiratory infection (33%), and pregnancy and parturition (10%).

CONCLUSIONS

Thirty-five percent of SD patients perceive their disorder to have a sudden onset with identified inciting events. This prevalence raises questions regarding possible behavioral and environmental factors surrounding the onset of this disorder.

Chronic (neuropathic) corneal pain and blepharospasm: five case reports

Pain and focal dystonias have been associated with chronic pain conditions such as complex regional pain syndrome. Corneal pain, frequently known as "dry eye", may be a neuropathic pain condition with abnormalities of the nerve plexus. Here we present 5 case histories of patients with defined corneal pain (with associated neuropathic features) and objective measures of changes in the nerve plexus and associated blepharospasm. A putative relationship between pain and blepharospasm suggests potential involvement of the basal ganglia in both these conditions.