The spectrum of disorders presenting as adult-onset focal lower extremity dystonia

Isolated and combined dystonias: Update

Dystonia is a hyperkinetic movement disorder with a unique motor phenomenology that can manifest as an isolated clinical syndrome or combined with other neurological features. This chapter reviews the characteristic features of dystonia phenomenology and the syndromic approach to evaluating the disorders that may allow us to differentiate the isolated and combined syndromes. We also present the most common types of isolated and combined dystonia syndromes. Since accelerated gene discoveries have increased our understanding of the molecular mechanisms of dystonia pathogenesis, we also present isolated and combined dystonia syndromes by shared biological pathways. Examples of these converging mechanisms of the isolated and combined dystonia syndromes include (1) disruption of the integrated response pathway through eukaryotic initiation factor 2 alpha signaling, (2) disease of dopaminergic signaling, (3) alterations in the cerebello-thalamic pathway, and (4) disease of protein mislocalization and stability. The discoveries that isolated and combined dystonia syndromes converge in shared biological pathways will aid in the development of clinical trials and therapeutic strategies targeting these convergent molecular pathways.

Functional dystonia: A pitfall for the foot and ankle surgeon

Functional dystonia represents a condition where psychological distress is being expressed as involuntary muscle contractions. In the foot and ankle, it most commonly presents as a sudden onset of a painful fixed ankle/hindfoot deformity in a female patient with a history of trivial trauma or surgery. The "fixed deformity" found on clinical examination is usually correctable under general anesthesia. Less commonly, it can present in the toes or may present as paroxysmal muscle movements rather than a fixed deformity. CRPS may occur concurrently with the dystonia. Failure to consider the diagnosis leads to a long delay in appropriate diagnosis, patient distress and unnecessary or even harmful surgery. A better approach to this clinical syndrome is to define it as fixed abnormal posturing that is most commonly psychogenic. Early referral to a movement disorder clinic is recommended. The prognosis is generally poor as less than a quarter of patients report subjective long-term improvement even when managed in a movement disorder clinic. Foot and ankle surgeons should, whenever possible, avoid operating on patients with functional dystonia in order to avoid symptomatic deterioration.

Surgical outcome of a post-traumatic dystonic foot: Case report and literature review

Post-traumatic dystonia is an underrecognized condition that can present with bizarre symptoms after trauma, usually out of proportion to the trigger event. We describe the case of a 31-year-old man with a severe lower extremity deformity, gradually developed after minor trauma. An interdisciplinary treatment was tried without any improvement and surgery was performed as a rescue approach. Tibialis anterior tendon transfer and hindfoot triple arthrodesis were carried out, successfully achieving a plantigrade foot and a functional gait. Despite the scarce literature available about functional results of surgery in dystonic feet, we present a step-by-step comprehensive approach to this disorder. LEVEL OF CLINICAL EVIDENCE: 4.

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.

Focal Task-Specific Lower Limb Dystonia Only When Walking Stairs: Is It a New Disease Entity?

Introduction: Focal task-specific dystonia in the lower limb or foot often occurs only during walking, running, hiking, or cycling. Several medications and botulinum toxin injection are effective in patients with this disorder. The objective of this study was to understand the spectrum of focal task-specific dystonia in the lower limb only when walking stairs and to compare other types of task-specific dystonia.

Methods: All original articles and case reports were collected and reviewed using PubMed. In addition, all video clips of published cases were evaluated, and patients' clinical findings analyzed. The present study included 12 patients described in previous studies and five new Asian patients found in the medical records.

Results: Most of the patients were women, and the onset age was 42 years. Ten patients were classified as the Kicking type, including three patients with the rKicking type, and six patients were considered as the Lifting type; however, only one patient was not included in any of the types. Symptoms in most of the patients did not improve with any medications or botulinum toxin injection. The symptoms of most patients did not change over a long time.

Conclusion: Most patients showed the dystonic symptom when walking downstairs rather than upstairs. Psychogenic dystonia is a disease differentially diagnosed with this dystonia. Unlike other types of focal task-specific dystonia, the response to treatment was disappointing because most of the medications and botulinum toxin injection were not effective. The prognosis is completely different from that of other types of focal task-specific dystonia.

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.

A Delphi study to develop practical diagnostic guidelines for visual stress (pattern-related visual stress)

PURPOSE

Visual stress (VS) is characterised by symptoms of visual perceptual distortions and eyestrain when viewing text, symptoms that are alleviated by individually prescribed coloured filters. A recent review supports the existence of VS and its treatment, but noted that controversy remains, in part due to inconsistencies in the diagnosis of the condition. The present paper reviews the diagnostic criteria for VS in the literature and reports a Delphi analysis of the criteria currently used in clinical practice.

METHODS

Twenty-six eyecare practitioners were invited to participate in a Delphi study. They were selected because they were frequent prescribers of precision tinted lenses. In the first round they were sent a list of the indicators for which there is literature to suggest a relevance in the diagnosis of VS. The practitioners were invited to rank the indicators and add any additional criteria they use in diagnosis. In the second round a revised list was circulated, including items added from the responses in the first round.

RESULTS

The respondents included optometrists, orthoptists and opticians. In the first round the response rate was 85%. Ninety-one percent of those who participated in the first round also responded in the second round. Strong indicators in the second round included the symptom of words moving when reading, voluntary use of an overlay for a prolonged period, improved performance of ≥15% with an overlay on the Wilkins Rate of Reading test, and an abnormally high score on the Pattern Glare Test.

CONCLUSIONS

The strongest diagnostic criteria are combined in a diagnostic tool. This is proposed as a guide for clinical practice and further research.

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.

l-Dopa in dystonia

“Every child exhibiting dystonia merits anl-dopa trial, lest the potentially treatable condition of dopa-responsive dystonia (DRD) is missed” has been a commonly cited and highly conserved adage in movement disorders literature stemming from the 1980s. We here provide a historical perspective on this statement, discuss the current diagnostic and therapeutic applications ofl-dopa in everyday neurologic practice, contrast these with its approved indications, and finish with our view on both a diagnostic and therapeutic trial in children and adults with dystonia. In light of the relatively low prevalence of DRDs, the large interindividual variation in the requiredl-dopa dose, the uncertainty about an adequate trial duration, the substantial advances in knowledge on etiology and pathophysiology of these disorders, and the availability of various state-of-the-art diagnostic tests, we think that a diagnosticl-dopa trial as a first step in the approach of early-onset dystonia (≤25 years) is outdated. Rather, in high-resource countries, we suggest to usel-dopa after biochemical corroboration of a defect in dopamine biosynthesis, in genetically confirmed DRD, or if nigrostriatal degeneration has been demonstrated by nuclear imaging in adult patients presenting with lower limb dystonia. Furthermore, our literature study on the effect of a therapeutic trial to gain symptomatic relief revealed thatl-dopa has occasionally proven beneficial in several established “non-DRDs” and may therefore be considered in selected cases of dystonia due to other causes. In summary, we argue against the application ofl-dopa in every patient with early-onset dystonia and support a more rational therapeutic use.

How Many Dystonias? Clinical Evidence

Literary reports on dystonia date back to post-Medieval times. Medical reports are instead more recent. We review here the early descriptions and the historical establishment of a consensus on the clinical phenomenology and the diagnostic features of dystonia syndromes. Lumping and splitting exercises have characterized this area of knowledge, and it remains largely unclear how many dystonia types we are to count. This review describes the history leading to recognize that focal dystonia syndromes are a coherent clinical set encompassing cranial dystonia (including blepharospasm), oromandibular dystonia, spasmodic torticollis, truncal dystonia, writer's cramp, and other occupational dystonias. Papers describing features of dystonia and diagnostic criteria are critically analyzed and put into historical perspective. Issues and inconsistencies in this lumping effort are discussed, and the currently unmet needs are critically reviewed.

Deep brain stimulation for dystonia: a novel perspective on the value of genetic testing

The dystonias are a group of disorders characterized by excessive muscle contractions leading to abnormal movements and postures. There are many different clinical manifestations and underlying causes. Deep brain stimulation (DBS) provides an effect treatment, but outcomes can vary considerably among the different subtypes of dystonia. Several variables are thought to contribute to this variation including age of onset and duration of dystonia, specific characteristics of the dystonic movements, location of stimulation and stimulator settings, and others. The potential contributions of genetic factors have received little attention. In this review, we summarize evidence that some of the variation in DBS outcomes for dystonia is due to genetic factors. The evidence suggests that more methodical genetic testing may provide useful information in the assessment of potential surgical candidates, and in advancing our understanding of the biological mechanisms that influence DBS outcomes.

A systematic review of controlled trials on visual stress using Intuitive Overlays or the Intuitive Colorimeter

Claims that coloured filters aid reading date back 200 years and remain controversial. Some claims, for example, that more than 10% of the general population and 50% of people with dyslexia would benefit from coloured filters lack sound evidence and face validity. Publications with such claims typically cite research using methods that have not been described in the scientific literature and lack a sound aetiological framework. Notwithstanding these criticisms, some researchers have used more rigorous selection criteria and methods of prescribing coloured filters that were developed at a UK Medical Research Council unit and which have been fully described in the scientific literature. We review this research and disconfirm many of the more extreme claims surrounding this topic. This literature indicates that a minority subset of dyslexics (circa 20%) may have a condition described as visual stress which most likely results from a hyperexcitability of the visual cortex. Visual stress is characterised by symptoms of visual perceptual distortions, headaches, and eyestrain when viewing repetitive patterns, including lines of text. This review indicates that visual stress is distinct from, although sometimes co-occurs with, dyslexia. Individually prescribed coloured filters have been shown to improve reading performance in people with visual stress, but are unlikely to influence the phonological and memory deficits associated with dyslexia and therefore are not a treatment for dyslexia. This review concludes that larger and rigorous randomised controlled trials of interventions for visual stress are required. Improvements in the diagnosis of the condition are also a priority.

Adult onset primary focal dystonia of the foot: an orthopaedic intervention

A 54-year-old woman presented to a foot centre with a chief symptom of cramping in her toes, which, she believed, was of a secondary cause originating from a bunion. She was treated conservatively; however, she returned a month later as the symptoms had progressed to painful cramping of toes, toe-curling and instability while walking, due to involuntary movement of her toes. It was believed that the patient presented with a rare case of primary adult onset focal foot dystonia. This case report explains dystonia further in detail and delves into the different treatment and management options available today, including the unique orthopaedic intervention provided for this patient.

Diagnosis and treatment of dystonia

The dystonias are a group of disorders characterized by excessive involuntary muscle contractions leading to abnormal postures and/or repetitive movements. A careful assessment of the clinical manifestations is helpful for identifying syndromic patterns that focus diagnostic testing on potential causes. If a cause is identified, specific etiology-based treatments may be available. In most cases, a specific cause cannot be identified, and treatments are based on symptoms. Treatment options include counseling, education, oral medications, botulinum toxin injections, and several surgical procedures. A substantial reduction in symptoms and improved quality of life is achieved in most patients by combining these options.

Animal models for dystonia

Symptomatic animal models have clinical features consistent with human disorders and are often used to identify the anatomical and physiological processes involved in the expression of symptoms and to experimentally demonstrate causality where it would be infeasible in the patient population. Rodent and primate models of dystonia have identified basal ganglia abnormalities, including alterations in striatal GABAergic (ie, transmitting or secreting γ-aminobutyric acid) and dopaminergic transmission. Symptomatic animal models have also established the critical role of the cerebellum in dystonia, particularly abnormal glutamate signaling and aberrant Purkinje cell activity. Further, experiments suggest that the basal ganglia and cerebellum are nodes in an integrated network that is dysfunctional in dystonia. The knowledge gained from experiments in symptomatic animal models may serve as the foundation for the development of novel therapeutic interventions to treat dystonia. © 2013 Movement Disorder Society.

Assessment of patients with isolated or combined dystonia: an update on dystonia syndromes

The clinical evaluation of a patient with dystonia is a stepwise process, beginning with classification of the phenomenology of the movement disorder(s), then formulation of the dystonia syndrome, which, in turn, leads to a targeted etiological differential diagnosis. In recent years, there have been significant advances in our understanding of the etiological basis of dystonia, aided especially by discoveries in imaging and genetics. In this review, we provide an update on the assessment of a patient with dystonia, including the phenomenology of dystonia and highlighting how to integrate clinical, imaging, blood, and neurophysiological investigations in order to formulate a dystonia syndrome. Evolving or emerging dystonia syndromes are reviewed, and potential etiologies of these as well as established dystonia syndromes listed to guide diagnostic testing. © 2013 Movement Disorder Society.

Focal task-specific lower extremity dystonia associated with intense repetitive exercise: a case series

BACKGROUND

Focal task-specific dystonia of the lower extremity associated with intense repetitive exercise has recently been recognized. The clinical course, treatment response and prognosis remain poorly understood.

METHODS

Individuals with lower extremity task-specific dystonia evaluated at UCSF's Movement Disorders Center (2004-2012) were eligible for this descriptive case study series if he/she had a history of strenuous and prolonged exercise involving the lower extremity and had no abnormal neurological or medical conditions to explain the involuntary movements. Data was gathered from the medical history and a self-report questionnaire. The findings were compared to 14 cases previously reported in the literature.

RESULTS

Seven cases (4M/3F) were identified with a diverse set of exercise triggers (cycling, hiking, long-distance running, drumming). The mean age of symptom onset was 53.7 ± 6.1 years. The median symptom duration prior to diagnosis was 4 (9.5) years. Several patients underwent unnecessary procedures prior to being appropriately diagnosed. Over a median of 2 (3.5) years, signs and symptoms progressed to impair walking. Seven patients had improvement in gait with treatment (e.g. botulinum toxin injections, benzodiazepines, physical therapy, bracing, body weight supported gait training and/or functional electrical stimulation of the peroneal nerve) and six returned to a reduced intensity exercise routine.

CONCLUSIONS

Isolated lower extremity dystonia associated with strenuous, repetitive exercise is relatively uncommon, but disabling and challenging to treat. The pathophysiology may be similar to task-specific focal dystonias of the upper limb. Prompt recognition of leg dystonia associated with extreme exercise could minimize unnecessary testing and procedures, and facilitate earlier treatment.

Levodopa Responsiveness in Adult-onset Lower Limb Dystonia is Associated with the Development of Parkinson's Disease

Background

Adult-onset primary lower limb dystonia (AOPLLD) has been reported as an early sign of Parkinson’s disease (PD) or Parkinson-plus syndrome in case series. No prior systematic analysis has assessed clinical clues predicting later development of PD or Parkinson-plus syndrome.

Methods

We identified patients with AOPLLD from medical records. We excluded patients who had not been diagnosed by a neurologist, and who had a pre-existing diagnosis of PD, psychogenic, or secondary dystonia. Records were subdivided into those who later developed PD or Parkinson-plus disorders and those who did not. The following clinical characteristics were compared between the two groups: dystonia onset age, type of dystonia, levodopa response, anticholinergic response, and family history of Parkinsonism or tremor.

Results

Twenty-two AOPLLD patients were identified: 77% female; the median dystonia onset age was 53 years. Eight (37%) developed Parkinson’s disease; 2 (9%) developed corticobasal syndrome. Twelve patients (54%) did not develop Parkinsonism after a median follow-up period of 1.5 years. There was a significant difference in leg dystonia levodopa response between the two groups (p = 0.02).

Conclusion

In patients with AOPLLD, leg dystonia with levodopa response is associated with the future development of PD.

The functional neuroimaging correlates of psychogenic versus organic dystonia

The neurobiological basis of psychogenic movement disorders remains poorly understood and the management of these conditions difficult. Functional neuroimaging studies have provided some insight into the pathophysiology of disorders implicating particularly the prefrontal cortex, but there are no studies on psychogenic dystonia, and comparisons with findings in organic counterparts are rare. To understand the pathophysiology of these disorders better, we compared the similarities and differences in functional neuroimaging of patients with psychogenic dystonia and genetically determined dystonia, and tested hypotheses on the role of the prefrontal cortex in functional neurological disorders. Patients with psychogenic (n = 6) or organic (n = 5, DYT1 gene mutation positive) dystonia of the right leg, and matched healthy control subjects (n = 6) underwent positron emission tomography of regional cerebral blood flow. Participants were studied during rest, during fixed posturing of the right leg and during paced ankle movements. Continuous surface electromyography and footplate manometry monitored task performance. Averaging regional cerebral blood flow across all tasks, the organic dystonia group showed abnormal increases in the primary motor cortex and thalamus compared with controls, with decreases in the cerebellum. In contrast, the psychogenic dystonia group showed the opposite pattern, with abnormally increased blood flow in the cerebellum and basal ganglia, with decreases in the primary motor cortex. Comparing organic dystonia with psychogenic dystonia revealed significantly greater regional blood flow in the primary motor cortex, whereas psychogenic dystonia was associated with significantly greater blood flow in the cerebellum and basal ganglia (all P < 0.05, family-wise whole-brain corrected). Group × task interactions were also examined. During movement, compared with rest, there was abnormal activation in the right dorsolateral prefrontal cortex that was common to both organic and psychogenic dystonia groups (compared with control subjects, P < 0.05, family-wise small-volume correction). These data show a cortical–subcortical differentiation between organic and psychogenic dystonia in terms of regional blood flow, both at rest and during active motor tasks. The pathological prefrontal cortical activation was confirmed in, but was not specific to, psychogenic dystonia. This suggests that psychogenic and organic dystonia have different cortical and subcortical pathophysiology, while a derangement in mechanisms of motor attention may be a feature of both conditions.

Adult-onset Idiopathic Focal Lower Extremity Dystonia: A Rare Task-Specific Dystonia

Background

Adult-onset focal lower extremity (LE) dystonia is rare, but there have recently been a number of case series that have reported an idiopathic variant triggered during ambulation.

Methods

We describe nine patients with idiopathic, focal task-specific LE dystonia. We conducted a comparative analysis that included our cohort and several recently published case series to further characterize the disorder.

Results

A total of 48 patients (37 female, 11 male) were compared. The average age of onset was 48 years; 36 patients had distal extremity involvement (75%), 5 proximal (10%), and 7 both proximal and distal (15%). Among 33 patients in which the dystonic side was known, 20 were affected on the left (61%). Inversion of the foot with flexion of one or more toes was the most prevalent pattern in those with distal extremity involvement.

Discussion

This is a novel task-specific dystonia triggered during ambulation that is often misdiagnosed as an orthopedic or psychogenic issue.

Convergent mechanisms in etiologically-diverse dystonias

INTRODUCTION

Dystonia is a neurological disorder associated with twisting motions and abnormal postures, which compromise normal movements and can be both painful and debilitating. It can affect a single body part (focal), several contiguous regions (segmental), or the entire body (generalized), and can arise as a result of numerous causes, both genetic and acquired. Despite the diversity of causes and manifestations, shared clinical features suggest that common mechanisms of pathogenesis may underlie many dystonias.

AREAS COVERED

Shared themes in etiologically-diverse dystonias exist at several biological levels. At the cellular level, abnormalities in the dopaminergic system, mitochondrial function and calcium regulation are often present. At the anatomical level, the basal ganglia and the cerebellum are frequently implicated. Global CNS dysfunction, specifically aberrant neuronal plasticity, inhibition and sensorimotor integration, are also observed in a number of dystonias. Using clinical data and data from animal models, this article seeks to highlight shared pathways that may be critical in understanding mechanisms and identifying novel therapeutic strategies in dystonia.

EXPERT OPINION

Identifying shared features of pathogenesis can provide insight into the biological processes that underlie etiologically diverse dystonias, and can suggest novel targets for therapeutic intervention that may be effective in a broad group of affected individuals.

Focal limb dystonia

Limb dystonia (LD) refers to dystonia affecting one arm or leg. Depending on the site of onset, age at onset, and the etiology, progression and prognosis will be different. Usually young-onset primary dystonia affects the lower limbs and tends to generalize, while in adult-onset, it appears in the arm and remains focal. Lower limb dystonia in adults is rare as a primary cause, and parkinsonism or other neurological diseases must always be ruled out. In the text that follows, we review the main clinical features of the primary and secondary limb dystonias considering the age at onset and etiology.

Lower limb involvement in adult-onset primary dystonia: frequency and clinical features

BACKGROUND AND PURPOSE

Despite the growing number of reports describing adult-onset primary lower limb dystonia (LLD) this entity has never been systematically evaluated in the general population of patients with primary adult-onset dystonia.

METHODS

From outpatients with adult-onset primary dystonia attending nine Italian University centres for movement disorders we consecutively recruited 579 patients to undergo a standardized clinical evaluation.

RESULTS

Of the 579 patients assessed, 11 (1.9%) (8 women, 3 men) had LLD, either alone (n = 4, 0.7%) or as part of a segmental/multifocal dystonia (n = 7, 1.2%). The age at onset of LLD (47.9 +/- 17 years) was significantly lower than the age at onset of cranial dystonias (57.9 +/- 10.7 years for blepharospasm, and 58.9 +/- 11.8 years for oromandibular dystonia) but similar to that of all the other adult-onset primary dystonias. The lower limb was either the site of dystonia onset (36.4%) or the site of dystonia spread (63.6%). In patients in whom LLD was a site of spread, dystonia seemed to spread following a somatotopic distribution. Only one patient reported a recent trauma involving the lower limb whereas 36.4% of the patients reported pain at the site of LLD. Only 64% of our patients needed treatment for LLD, and similarly to previously reported cases, the most frequently tried treatments was botulinum toxin and trihexyphenidyl.

CONCLUSION

The lower limb is an uncommon but possible topographical site of dystonia in adulthood that should be kept in consideration during clinical evaluation.