Gender Differences in Task Specific Dystonia: What Can we Learn from Musician's Dystonia?

BACKGROUND: Musician's Dystonia (MD) is a task specific, focal dystonia which usually occurs only at the instrument. The pathophysiology is not fully understood, but several risk factors like over-practice and genetic predisposition are known. Interestingly, 80% of those affected are men, which stands in contrast to the gender distribution in other focal dystonias, such as cervical dystonia. OBJECTIVES: Our aim was to evaluate the difference in women and men with regard to risk factors leading to MD. METHODS: We investigated known risk factors for MD in a large cohort of 364 MD patients by retrospectively collecting data on practice behavior and family history. RESULTS: In line with previous studies, we found a ratio of ~4:1 men to women. Age at onset of MD was significantly lower in women; however, subsequent analysis revealed that it was a positive family history (FH+) and not gender that was associated with a lower age at onset. Furthermore, we found that those with negative family history had accumulated more practice time until onset of MD. CONCLUSIONS: These results imply that the earlier age at onset in women did not depend on gender but was due to the higher proportion of a positive family history. In contrast, men were less likely to have a positive family history, suggesting that genetic factors may not be the primary reason for the higher prevalence of MD in men. Instead, differences in practice behaviors between men and women may contribute to this gender disparity.

Does thyroid diseases contribute to the natural history of idiopathic adult-onset dystonia? Data from the Italian Dystonia Registry.

A few earlier observations and recent controlled studies pointed to the possible contribution of thyroid diseases in idiopathic adult-onset dystonia (IAOD). The aim of this study was to investigate the association between thyroid status and clinical characteristics of IAOD, focusing on dystonia localization, spread, and associated features such as tremors and sensory tricks. Patients were identified from those included in the Italian Dystonia Registry, a multicentre dataset of patients with adult-onset dystonia. The study population included 1518 IAOD patients. Patients with hypothyroidism and hyperthyroidism were compared with those without any thyroid disease. In the 1518 IAOD patients, 167 patients (11%; 95% CI 9.5-12.6%) were diagnosed with hypothyroidism and 42 (2.8%; 95% CI 1.99-3.74) with hyperthyroidism. The three groups were comparable in age at dystonia onset, but there were more women than men in the groups with thyroid disease. Analysing the anatomical distribution of dystonia, more patients with blepharospasm were present in the hyperthyroidism group, but the difference did not reach statistical significance after the Bonferroni correction. The remaining dystonia-affected body sites were similarly distributed in the three groups, as did dystonia-associated features and spread. Our findings provided novel information indicating that the high rate of thyroid diseases is not specific for any specific dystonia subpopulation and does not appear to influence the natural history of the disease.

Demographics and Clinical Characteristics Associated with the Spread of New-Onset Laryngeal Dystonia.

OBJECTIVES: Adult-onset idiopathic laryngeal dystonia (LD) can be associated with the risk of spread to muscles in the body. Subjects with extralaryngeal onset of dystonia have exhibited spread to the larynx. Previous studies analyze the spread of other dystonias but emphasis has not been placed on LD. The objective was to identify demographic and clinical factors contributing to the spread of dystonia to and from the larynx. METHODS: Data were obtained from the Dystonia Coalition (DC)-patients from 49 international clinical centers. Clinical and demographic data was taken from 143 out of 409 patients with diagnosed LD. Patient criteria included adult-onset LD diagnosed on exam with no co-morbid neurologic conditions and no dystonia in other locations. RESULTS: Among the 143 patients, 94 (65.7%) patients were diagnosed with focal laryngeal onset, with the remainder having extralaryngeal onset. Family history and age at study were statistically significant indicators of a patient developing laryngeal versus extralaryngeal onset of dystonia. Among the laryngeal onset group, 21 cases (22.3%) had an average time of 5.81 ± 5.79 years to spread from diagnosis, most commonly to neck (61.9%). Among extralaryngeal onset patients, mean time of larynx spread was 7.92 ± 7.737 years, most commonly to neck (22.7%). CONCLUSIONS: Our data indicates approximately a quarter of patients with laryngeal-onset dystonia will exhibit spread. There were no demographic or clinical factors that were statistically predictive of the likelihood of spread from larynx. Patients with dystonia elsewhere in the body should be counseled on the possibility of spread to larynx, and vice versa. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:2295-2299, 2024.

Incidence and risk factors for secondary extralaryngeal dystonia in patients with laryngeal dystonia.

BACKGROUND AND OBJECTIVES: Laryngeal dystonia (LD) is a focal dystonia affecting adductor and/or abductor muscles of the larynx. It can be isolated or may spread to extra laryngeal muscles. The aim of this study was to report the characteristics of LD over time in a large single-center study with a long follow-up. METHODS: Retrospective review of patients with LD referred to our institution between 1991 and 2021. Demographic data, time to diagnosis, type of LD, follow-up and spread of dystonia [SD] were recorded. Risk factors for spread of dystonia during follow-up were analyzed. RESULTS: Over the 30-year period, 516 patients (77.3 % female, median age 50 years, range 5-87 years) were analyzed. Three hundred and fifteen patients (61 %) had adduction laryngeal dystonia, 136 patients (26.4 %) had abduction laryngeal dystonia, 46 patients (8.9 %) had adductor respiratory laryngeal dystonia, 12 patients (2.3 %) had mixed laryngeal dystonia, and seven patients (1.4 %) had singer's laryngeal dystonia. A previous history of dystonia was found in 47 patients (9.1 %). A laryngeal tremor was found in 68 patients (13.2 %). Since the onset of symptoms, LD was diagnosed after a median of 3 years (IQR: 1.0, 7.0). SD occurred in 55 patients (10.7 %) after a median time of 4 year (IQR: 1.5, 13.0). Patients with mixed laryngeal dystonia had higher probability of SD (p = 0.018). DISCUSSION: This study reports a large European study of LD, with a long follow-up. SD occurred in 10.5 % of patients. Patients with mixed laryngeal dystonia had a higher probability of SD. A close follow-up may be recommended for patients with mixed laryngeal dystonia.

Dystonia and tremor: Do they have a shared biology?

Dystonia and tremor are the two most commonly encountered hyperkinetic movement disorders encountered in clinical practice. While there has been substantial progress in the research on these two disorders, there also exists a lot of gray areas. Entities such as dystonic tremor and tremor associated with dystonia occupy a major portion of the "gray zone". In addition, there is a marked clinical heterogeneity and overlap of several clinical and epidemiological features among dystonia and tremor. These facts raise the possibility that dystonia and tremor could be having shared biology. In this chapter, we revisit critical aspects of this possibility that may have important clinical and research implications in the future. We comprehensively review the points in favor and against the theory that dystonia and tremor have shared biology from clinical, epidemiological, genetic and neuroimaging studies.

Tremor is associated with familial clustering of dystonia.

INTRODUCTION: Dystonia is a movement disorder of variable etiology and clinical presentation and is accompanied by tremor in about 50% of cases. Monogenic causes in dystonia are rare, but also in the group of non-monogenic dystonias 10-30% of patients report a family history of dystonia. This points to a number of patients currently classified as idiopathic that have at least in part an underlying genetic contribution. The present study aims to identify clinical and demographic features associated with heritability of yet idiopathic dystonia. METHODS: Seven hundred thirty-three datasets were obtained from the DysTract dystonia registry, patients with acquired dystonia or monogenic causes were excluded. Affected individuals were assigned to a familial and sporadic group, and clinical features were compared across these groups. Additionally, the history of movement disorders was also counted in family members. RESULTS: 18.2% of patients reported a family history of dystonia. Groups differed in age at onset, disease duration and presence of tremor on a descriptive level. Logistic regression analysis revealed that tremor was the only predictor for a positive family history of dystonia (OR 2.49, CI = 1.54-4.11, p < 0.001). Tremor turned out to be the most common movement disorder in available relatives of patients, and presence of tremor in relatives was associated with tremor in index patients (X2(1) = 16.2, p < 0.001). CONCLUSIONS: Tremor is associated with an increased risk of familial clustering of dystonia and with a family history of tremor itself. This indicates a hereditable dystonia-tremor syndrome with a clinical spectrum ranging from tremor-predominant diseases to dystonia.

Oromandibular Dystonia: Clinical and Demographic Data from Eight-Two Patients.

Objective: This study aimed to determine the demographic and clinical characteristics of patients with oromandibular dystonia (OMD). Background: Dystonia is a movement disorder characterized by sustained involuntary muscle contractions that often cause abnormal postures. OMD is a rare focal dystonia that affects the tongue, jaw, and mouth. OMD, which is a rare public health problem, is often recognized as psychogenic and there are delays in its diagnosis and treatment. Methods: Patients with OMD, both isolated and combined, followed at our Movement Disorders Outpatient Clinic between 2004 and 2021 were enrolled in this study. Age, sex, age at onset, and disease duration were recorded. The type of OMD, affected muscles, etiologies of accompanying neurological disorders, and treatment were noted. Results: A total of 82 patients (44 women, 38 men) were included in this study. Among these, 39 patients had isolated OMD, and 43 patients had either segmental or generalized dystonia. Seven patients reported a family history of dystonia. Only nine patients reported a sensory trick. The average disease duration was 6.01 ± 3.73 (range, 1-29) years, and the average age at onset was 43.34 ± 18.24 (range, 1-78) years. The disease etiology was unknown (idiopathic) in most patients. Fifteen patients reported task-specific dystonia. The most common type of dystonia was jaw-opening dystonia. Conclusion: OMD is focal dystonia that significantly affects the quality of life. This study adds more data to the literature by defining the clinical features of this rare disorder and draws attention to this neglected type of dystonia.

The epidemiology of dystonia: the Hannover epidemiology study.

The prevalence of dystonia has been studied since the 1980s. Due to different methodologies and due to varying degrees of awareness, resulting figures have been extremely different. We wanted to determine the prevalence of dystonia according to its current definition, using quality-approved registries and based on its relevance for patients, their therapy and the health care system. We applied a service-based chart review design with the City of Hannover as reference area and a population of 525,731. Barrier-free comprehensive dystonia treatment in few highly specialised centres for the last 30 years should have generated maximal dystonia awareness, a minimum of unreported cases and a high degree of data homogeneity. Prevalence [n/1mio] and relative frequency is 601.1 (100%) for all forms of dystonia, 251.1 (42%) for cervical dystonia, 87.5 (15%) for blepharospasm, 55.2 (9%) for writer's cramp, 38.0 (6%) for tardive dystonia, 32.3 (5%) for musician's dystonia, 28.5 (5%) for psychogenic dystonia, 26.6 (4%) for generalised dystonia, 24.7 (4%) for spasmodic dysphonia, 20.9 (3%) for segmental dystonia, 15.2 (3%) for arm dystonia and 13.3 (2%) for oromandibular dystonia. Leg dystonia, hemidystonia and complex regional pain syndrome-associated dystonia are very rare. Compared to previous meta-analytical data, primary or isolated dystonia is 3.3 times more frequent in our study. When all forms of dystonia including psychogenic, generalised, tardive and other symptomatic dystonias are considered, our dystonia prevalence is 3.7 times higher than believed before. The real prevalence is likely to be even higher. Having based our study on treatment necessity, our data will allow better allocation of resources for comprehensive dystonia treatment.

Task-specific dystonia in hairdressers: a questionnaire survey and review of the literature.

Hairdresser dystonia is one of the occupational dystonias and task-specific movement disorders occurring as a result of long-term repetitive cutting with scissors. The task-specific dystonia manifests itself as a loss of voluntary motor control during extensive practice of cutting requiring a high level of technical proficiency. The prevalence rate of hairdresser dystonia is not well-known worldwide. A questionnaire regarding dystonia was prepared for hairdressers. After sending the questionnaires to 800 hairdressers by direct mail, 134 answers were received by mail. Five of the 134 were suspected to have hairdresser-associated focal dystonia. Thus, 3.7% of hairdressers might have task-specific dystonia. This report was limited because of the small number of participants. However, this research is valuable because it was difficult to find a patient with suspected dystonia due to concerns related to job security.

Comprehensive analysis of non-motor symptoms and their association with quality of life in Writer's cramp.

OBJECTIVE: Limited studies have focused on non-motor symptoms (NMS) in patients with Writer's cramp (WC). The current study aimed to examine the frequency of NMS and their association with health-related quality of life (HR-QoL) in patients with WC. METHODS: A total of 80 patients with WC and 69 healthy controls (HCs) were enrolled. Motor symptoms was assessed by Burke-Fahn-Marsden dystonia rating scale and NMS was evaluated through several specific scales, including Hamilton depression rating scale-24 items (HDRS-24), Hamilton anxiety rating scale, Epworth sleepiness scale, Pittsburgh sleep quality index, fatigue severity scale (FSS), numerical rating scale for pain, and Montreal cognitive assessment. The HR-QoL was assessed using 36-item short form health survey (SF-36), which can be divided into physical component summary (PCS) and mental component summary (MCS). Multiple linear regression was used to analysis the association between each NMS and HR-QoL. RESULTS: The patients presented more symptoms of depression, anxiety, poor quality of sleep, excessive daytime sleepiness, and fatigue than the HCs. The most frequent NMS in patients with WC was anxiety (51.25%) and depression (46.25%) symptoms. We found that motor symptoms had no association with HR-QoL. Higher scores of HDRS-24 were associated with lower scores of SF-36 in PCS and MCS. Meantime, higher scores of FSS were significantly associated with lower scores of SF-36 in MCS. CONCLUSION: The NMS was prevalent in patients with WC, with frequent anxiety and depression symptoms. Depression symptoms and fatigue had a strongly negative impact on HR-QoL and deserve attention in clinic practice.

Fatigue is related to depression in idiopathic dystonia.

INTRODUCTION: Dystonia is a movement disorder presented with involuntary muscle contraction causing abnormal posture, movement, or both. Besides motor symptoms, patients may also report non-motor symptoms such as pain, anxiety, apathy, depression, sleep problems, fatigue, and cognitive impairment. The etiology of fatigue in patients with dystonia is not yet well understood. AIM: To evaluate the presence of fatigue, depression, anxiety, sleep disorders, and daily sleepiness in patients with focal and segmental dystonia and to determine which of these non-motor symptoms influence the occurrence and severity of fatigue. PATIENTS AND METHODS: Patients were surveyed for symptoms of fatigue, depression, anxiety, night-time sleep problems, and daily sleepiness using the Fatigue Assessment Scale, Beck Depression Inventory II, Beck Anxiety Inventory, Pittsburgh Sleep Questionnaire Index, and Epworth Sleepiness Scale. Demographic data (sex, age, and disease duration) were collected from patient medical records. On statistical analysis, we used SPSS for Windows 10. The level of significance was set at p<0.05. RESULTS: Sixty patients (43 female and 17 male) with focal or segmental dystonia were evaluated. Fatigue was reported by 67.2% of patients. Fatigue (general, physical, and mental fatigue) was found to correlate with depression, anxiety, and sleep problems. Daily sleepiness correlated only with mental fatigue. Disease duration, age, and gender did not influence the symptoms of fatigue. Multiple regression analysis showed that depression mostly predicted symptoms of general, physical, and mental fatigue. CONCLUSION: Depression mostly predicted symptoms of general, physical, and mental fatigue in patients with focal and segmental dystonia.

Adult-onset idiopathic dystonia: A national data-linkage study to determine epidemiological, social deprivation, and mortality characteristics.

BACKGROUND AND PURPOSE: Accurate epidemiological information is essential for the improved understanding of dystonia syndromes, as well as better provisioning of clinical services and providing context for diagnostic decision-making. Here, we determine epidemiological, social deprivation, and mortality characteristics of adult-onset idiopathic dystonia in the Welsh population. METHODS: A retrospective population-based cohort study using anonymized electronic health care data in Wales was conducted to identify individuals with dystonia between 1 January 1994 and 31 December 2017. We developed a case-ascertainment algorithm to determine dystonia incidence and prevalence, as well as characterization of the dystonia cohort, based on social deprivation and mortality. RESULTS: The case-ascertainment algorithm (79% sensitivity) identified 54,966 cases; of these cases, 41,660 had adult-onset idiopathic dystonia (≥20 years). Amongst the adult-onset form, the median age at diagnosis was 41 years, with males significantly older at time of diagnosis compared to females. Prevalence rates ranged from 0.02% in 1994 to 1.2% in 2017. The average annual incidence was 87.7/100,000/year, increasing from 49.9/100,000/year (1994) to 96.21/100,000/year (2017). In 2017, people with dystonia had a similar life expectancy to the Welsh population. CONCLUSIONS: We have developed a case-ascertainment algorithm, supported by the introduction of a neurologist-reviewed validation cohort, providing a platform for future population-based dystonia studies. We have established robust population-level prevalence and incidence values for adult-onset idiopathic forms of dystonia, with this reflecting increasing clinical recognition and identification of causal genes. Underlying causes of death mirrored those of the general population, including circulatory disorders, respiratory disorders, cancers, and dementia.

[Musculoskeletal hand disorders in musicians]. / Les pathologies musculo-squelettiques de la main chez les musiciens.

Music is often associated with joy, pleasure and leisure. However, like any other profession, it has its constraints and risks.The purpose of this update is to present a non-exhaustive inventory of musculoskeletal hand disorders most frequently associated with music practice.All music instruments are concerned. The difference lies in damage location as well as in the frequency of specific pathologies according to the used instrument. The most feared disorder by musicians is focal dystonia, which is characterized by a painless and repetitive coordination disorder. It only appears in the realization of specific professional movements. The overuse syndrome and the nerve entrapment syndrome constitute other dreaded disorders. Specific and multidisciplinary care is often necessary.

La musique rime souvent avec joie, plaisir et loisir. Cependant, comme toute autre profession, elle a ses contraintes et ses risques. Cette mise au point a pour objectif de faire un inventaire, non exhaustif, des pathologies musculo-squelettiques de la main les plus fréquemment associées à la pratique de la musique. Aucune famille d'instruments n'est épargnée. La différence réside dans la localisation de l'atteinte ainsi que dans la fréquence de l'association entre certains instruments et une pathologie précise. La dystonie de fonction, caractérisée par un trouble de la coordination indolore mais répétitif, est une pathologie redoutée par les musiciens. La symptomatologie ne se manifeste que lors de la réalisation de certains gestes professionnels précis. Le syndrome de surmenage ainsi que les syndromes canalaires peuvent également se rencontrer. Une prise en charge spécifique et multidisciplinaire est souvent nécessaire.

Perception of yips among professional Japanese golfers: perspectives from a network modelled approach.

'Yips' in golf is a complex spectrum of anxiety and movement-disorder that affects competitive sporting performance. With unclear etiology and high prevalence documented in western literature, the perception and management of this psycho-neuromuscular problem among Japanese elite golfers is unknown. The objective of this study was to explore factors associated with yips, investigate the performance deficits and the strategies implemented to prevent yips. We surveyed approx. 1300 professional golfers on their golfing habits, anxiety and musculoskeletal problems, kinematic deficits, changes in training and their outcomes. Statistical procedures included multiple logistic regression and network analysis. 35% of the respondents had experienced yips in their career, their odds increasing proportionally to their golfing experience. Regardless of musculoskeletal symptoms, about 57% of all yips-golfers attributed their symptoms to psychological causes. Network analysis highlighted characteristic movement patterns, i.e. slowing, forceful or freezing of movement for putting, approach and teeing shots respectively. Golfers' self-administered strategies to relieve yips were mostly inconsequential. Within the limits of our self-reported survey, most golfers perceived yips as a psychological phenomenon despite evidence pointing to a movement-disorder. While self-administered interventions were satisfactory at best, it may be imperative to sensitize golfers from a movement-disorder standpoint for early management of the problem.

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 prevalence of anxiety in adult-onset isolated dystonia: A systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Clinically relevant anxiety and anxiety disorders are commonly associated with adult-onset isolated dystonia, contributing substantially to quality-of-life impairment in patients with this movement disorder. However, the prevalence of anxiety symptoms and disorders in adult-onset isolated dystonia remains unclear. We aimed to conduct a systematic review and meta-analysis of the prevalence of anxiety symptoms/disorders in adult-onset isolated dystonia. METHODS: Studies reporting the prevalence of anxiety disorders determined through diagnostic interviews or from clinically relevant anxiety symptoms detected with rating scales were identified in three databases (MEDLINE, EMBASE and PsycINFO). The gray literature was also examined to detect studies not captured through the search strategy. RESULTS: The search strategy yielded 6535 citations; 34 studies met the inclusion criteria. The overall prevalence of clinically relevant anxiety symptoms and anxiety disorders for cervical dystonia was 40% (95% confidence interval [CI] 20% to 60%); for studies examining cranial dystonia it was 25% (95% CI 21% to 30%); for studies exploring mixed populations of adult-onset isolated dystonia it was 33.3% (95% CI 22% to 43%), 26% (95% CI 12% to 40%) for laryngeal dystonia, and 32% (95% CI 21% to 43%) for upper limb dystonia. Social phobia was the most prevalent anxiety disorder across the different forms of adult-onset isolated dystonia. Between-study statistical heterogeneity was high for most prevalence estimates. CONCLUSIONS: Clinically relevant anxiety and anxiety disorders are common across all forms of adult-onset isolated dystonia. New research avenues should explore and plan the development of pathways of care targeting these important non-motor features.

Tremor in Primary Monogenic Dystonia.

PURPOSE OF REVIEW: Tremor is an important phenotypic feature of dystonia with wide variability in the reported prevalence ranging from 14 to 86.67%. This variability may be due to the types of dystonia patients reported in different studies. This article reviews research articles reporting tremor in primary monogenic dystonia. RECENT FINDINGS: We searched the MDS gene data and selected all research articles reporting tremor in primary monogenic dystonia. Tremor was reported in nine dystonia genes, namely DYT-HPCA, DYT-ANO3, DYT-KCTD17, DYT-THAP1, DYT-PRKRA, DYT-GNAL, DYT-TOR1A, DYT-KMT2B, and DYT-SGCE in the descending order of its frequency. HPCA gene mutation is rare, but all reported patients had tremor. Similarly, tremor was reported in eight genes associated with dystonia parkinsonism, namely DYT-SLC6A3, DYT-TH, DYT-SPR, DYT-PTS, DYT-GCH1, DYT-TAF1, DYT-QDPR, and DYT-SCL30A10 in the descending order of its prevalence. DYT-HPCA and DYT-ANO3 gene showed the highest prevalence of tremor in isolated dystonia, and DYT-SLC6A3 has the highest prevalence of tremor in combined dystonia.

Predictive modeling of spread in adult-onset isolated dystonia: Key properties and effect of tremor inclusion.

BACKGROUND AND PURPOSE: Several clinical and demographic factors relate to anatomic spread of adult-onset isolated dystonia, but a predictive model is still lacking. The aims of this study were: (i) to develop and validate a predictive model of anatomic spread of adult-onset isolated dystonia; and (ii) to evaluate whether presence of tremor associated with dystonia influences model predictions of spread. METHODS: Adult-onset isolated dystonia participants with focal onset from the Dystonia Coalition Natural History Project database were included. We developed two prediction models, one with dystonia as sole disease manifestation ("dystonia-only") and one accepting dystonia OR tremor in any body part as disease manifestations ("dystonia OR tremor"). Demographic and clinical predictors were selected based on previous evidence, clinical plausibility of association with spread, or both. We used logistic regressions and evaluated model discrimination and calibration. Internal validation was carried out based on bootstrapping. RESULTS: Both predictive models showed an area under the curve of 0.65 (95% confidence intervals 0.62-0.70 and 0.62-0.69, respectively) and good calibration after internal validation. In both models, onset of dystonia in body regions other than the neck, older age, depression and history of neck trauma were predictors of spread. CONCLUSIONS: This predictive modeling of spread in adult-onset isolated dystonia based on accessible predictors (demographic and clinical) can be easily implemented to inform individuals' risk of spread. Because tremor did not influence prediction of spread, our results support the argument that tremor is a part of the dystonia syndrome, and not an independent or coincidental disorder.

Adult onset dystonia: A disorder of the collicular-pulvinar-amygdala network.

Models attempting to explain the pathogenesis of adult onset idiopathic focal dystonia often fail to accommodate the entire spectrum of this disorder: the diverse motor and non-motor symptoms, psychiatric and cognitive dysfunction, as well as the sub-clinical, physiological and anatomical, abnormalities. We propose, and present the accumulating evidence, that the adult onset dystonia syndrome is due to disruption in the covert-attentional network, the unconscious sub-cortical mechanism for the detection of potentially environmentally threatening (salient) stimuli, involving the collicular-pulvinar-amygdala network. A critical consideration of this network indicates a number of hypothesis-generated research questions aimed at elucidating the pathogenesis of adult onset dystonia. Given the rarity of adult onset dystonia, international, multidisciplinary, multicentre studies are required to elucidate the prevalence of non-motor symptoms in unaffected relatives, in particular, using temporal discrimination. Research focussing on the non-motor symptoms and the collicular-pulvinar-amygdala pathway may be the key to understanding adult-onset idiopathic focal dystonias (AOIFD) pathophysiology.