Prevalence of focal dystonias in the western area of Tottori Prefecture in Japan

Cannabidiol as an Adjunct to Botulinum Toxin in Blepharospasm - A Randomized Pilot Study

Purpose

The purpose of this study was to evaluate the safety and efficacy of low dose cannabidiol (CBD; Epidiolex) as adjunctive therapy for idiopathic adult-onset blepharospasm (BPS), as well as develop a novel objective assessment methodology to gauge response.

Methods

Prospective, randomized, double-masked, placebo-controlled crossover design of 6 months duration of 12 patients with BPS undergoing routine maximal botulinum toxin (BTX) therapy and experiencing breakthrough symptoms. Participants received their standard BTX every 3 months and were randomized to group A = CBD daily in cycle 1, followed by placebo in cycle 2 or group B = placebo followed by CBD. Videos recorded at days 0, 45, and 90 of each cycle were analyzed to quantify eyelid kinematics. The Jankovic Rating Scale (JRS) was used to provide a clinical rating.

Results

All 12 patients completed the study without adverse events. CBD decreased median eyelid closure amplitude by 19.1% (-1.66 mm, confidence interval [CI] = -3.19 to -0.14 mm, P = 0.03), decreased median eyelid closure duration by 15.8% (-18.35 ms, CI = -29.37 to -7.32 ms, P = 0.001), and increased the maximum eyelid closure velocity by 34.8% (-13.26 mm/ms, CI = -20.93 to -5.58 mm/ms, P = 0.001). The JRS showed a 0.5 reduction in severity and frequency, which was not statistically significant.

Conclusions

Low dose CBD was safely tolerated and improved several BPS kinematic parameters. The clinical scale suggested a direction of effect but may have been underpowered. Further studies are needed to better quantify the clinical relevance.

Translational Relevance

This work describes a novel assessment methodology and therapeutic approach to bBPS.

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.

Isolated Cervical Dystonia: Management and Barriers to Care

Background: Cervical dystonia (CD) is a rare disorder, and health care providers might be unfamiliar with its presentation, thus leading to delay in the initial diagnosis. The lack of awareness displays the need to highlight the clinical features and treatment in cervical dystonia. In our cohort, we have identified an earlier age of onset in men, despite an overall preponderance of affected women.

Objective: We aim to identify the prevalence, age of onset, spread, and treatment modalities of CD in the population. We also highlight the barriers which patients encounter related to diagnosis, follow-up, and treatment.

Methods: We reviewed 149 CD patients who attended specialized Dystonia Clinics over a 14-year period. Dystonia severity was rated using the Burke-Fahn-Marsden (BFM), Tsui, and Toronto Western Spasmodic Torticollis Rating Scales (TWSTRS). Mood and quality of life were assessed using Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and 36-Item Short Form Health Survey (SF-36).

Results: CD patients were majority White (91.3%) and more commonly female (75.8%). Men had an earlier median age of onset, 40.5 years (p = 0.044). BAI revealed a mean score of 7.2 (±6.4, n = 50) indicating minimal anxiety while BDI revealed a mean score of 7.30 (±7.6, n = 50) indicating minimal depression. The only SF-36 subscales associated with CD severity were physical functioning (p = 0.040) pain (p = 0.008) and general health (p = 0.014).

Conclusion: There appear to be gender differences in both the prevalence and age of onset of the disease. There was a 3-fold higher incidence in women than in men. CD patients of both sexes experience barriers to care, which can be reflected in their quality of life and time-to-diagnosis. In addition, males were less likely to experience an objective benefit with botulinum toxin treatment and more likely to discontinue care. Greater awareness of CD by health care providers is important to reduce the time-to-diagnosis.

Cervical dystonia incidence and diagnostic delay in a multiethnic population

BACKGROUND

Current cervical dystonia (CD) incidence estimates are based on small numbers in relatively ethnically homogenous populations. The frequency and consequences of delayed CD diagnosis is poorly characterized.

OBJECTIVES

To determine CD incidence and characterize CD diagnostic delay within a large, multiethnic integrated health maintenance organization.

METHODS

We identified incident CD cases using electronic medical records and multistage screening of more than 3 million Kaiser Permanente Northern California members from January 1, 2003, to December 31, 2007. A final diagnosis was made by movement disorders specialist consensus. Diagnostic delay was measured by questionnaire and health utilization data. Incidence rates were estimated assuming a Poisson distribution of cases and directly standardized to the 2000 U.S. census. Multivariate logistic regression models were employed to assess diagnoses and behaviors preceding CD compared with matched controls, adjusting for age, sex, and membership duration.

RESULTS

CD incidence was 1.18/100,000 person-years (95% confidence interval [CI], 0.35-2.0; women, 1.81; men, 0.52) based on 200 cases over 15.4 million person-years. Incidence increased with age. Half of the CD patients interviewed reported diagnostic delay. Diagnoses more common in CD patients before the index date included essential tremor (odds ratio [OR] 68.1; 95% CI, 28.2-164.5), cervical disc disease (OR 3.83; 95% CI, 2.8-5.2), neck sprain/strain (OR 2.77; 95% CI, 1.99-3.62), anxiety (OR 2.24; 95% CI, 1.63-3.11) and depression (OR 1.94; 95% CI, 1.4-2.68).

CONCLUSIONS

CD incidence is greater in women and increases with age. Diagnostic delay is common and associated with adverse effects. © 2019 International Parkinson and Movement Disorder Society.

Epidemiology of benign essential blepharospasm: A nationwide population-based retrospective study in Taiwan

IMPORTANCE

This study provides a nationwide, population-based data on the incidence of benign essential blepharospasm in Asian adults.

BACKGROUND

To describe the incidence, patient demographics, and risk factors associated with benign essential blepharospasm.

DESIGN

Population-based retrospective study.

PARTICIPANTS AND SAMPLES

A total of 1325 patients with benign essential blepharospasm were identified.

METHODS

Patients with diagnosis of blepharopsasm between January 2000 and December 2013 were sampled using the Longitudinal Health Insurance Database 2000. Secondary blepharospasm that may be related to neurological, trauma, and ocular surface disease were excluded.

MAIN OUTCOME MEASURED

Multivariate conditional logistic regression was used to estimate the odds ratios for potential risk factors of benign essential blepharospasm.

RESULTS

The mean annual incidence was 0.10‰ (0.07‰ for males, and 0.12‰ for females). The peak incidence was in the 50 to 59-year-old age group (0.19‰). People living in urban regions have more risk of developing blepharospasm comparing to people living in less urban regions (p <0.01). White-collar workers also have higher chance of having blepharospasm (p<0.001). Significant difference between control group and case group in hyperlipidemia (p <0.001), sleep disorders (p <0.001), mental disorders (depression, anxiety, obsessive compulsive disorder) (p <0.001), dry eye-related diseases (dry eye, Sjögren's syndrome) (p <0.001), Parkinson's disease (p <0.004), and rosacea (p <0.021) were also identified.

CONCLUSIONS AND RELEVANCE

Higher level of urbanization, white-collar work, sleep disorders, mental health diseases, dry eye-related diseases, Parkinsonism, and rosacea are possible risk factors for benign essential blepharospasm.

The prevalence of adult-onset isolated dystonia in Finland 2007-2016

BACKGROUND

Dystonia is a group of chronic diseases, causing considerable physical and psychosocial stress to patients and health care expenses. We studied the prevalence of different dystonia types in Finland in the years 2007-2016.

METHODS

All patients with an ICD-10 code of dystonia were retrieved from the national care register. Average age-adjusted yearly prevalence was assessed for adult-onset isolated idiopathic or hereditary dystonia types from patient records from the Uusimaa and Pirkanmaa provinces.

RESULTS

1316 patients were confirmed to have adult-onset isolated idiopathic or hereditary dystonia based on hospital records from two provinces. On average, the age-adjusted prevalence for all adult-onset dystonia was 405 per million and for cervical dystonia 304 per million. For other dystonia types the prevalence ranged from 1-33 per million.

CONCLUSIONS

Adult onset cervical dystonia was the most common type of dystonia with relatively high prevalence in Finland compared with other countries. The prevalence of other types of dystonia was similar compared with other European studies. The higher prevalence of cervical dystonia may be partially explained by the better coverage of patients in public health care, but genetic and exogenous factors might contribute to it.

Five-Year Retrospective Review of Cases with Benign Essential Blepharospasm and Hemifacial Spasm Presenting in a Tertiary Eye Care Center in North India

Retrospective analysis of epidemiological and clinical characteristics of patients diagnosed with benign essential blepharospasm and hemifacial spasm who reported to the oculoplasty clinic of a tertiary eye care center in north India between January 2010 and April 2015 was carried out. Dry eye, as well as all the local factors that can cause blepharospasm or hemifacial spasm, was ruled out. Systemic evaluation was done to rule out any neurological disorder. A detailed history was taken to rule out any associated psychiatric disorders as well as use of any medication which could be responsible for dystonic movements. In every patient of hemifacial spasm, magnetic resonance imaging (MRI) of the brain was done for any facial nerve compression or tumor involving posterior fossa. Botulinum type A injections were given after assessing their requirements on the basis of guidelines given by Jankovic et al.

Maladaptive Plasticity Induces Degradation of Fine Motor Skills in Musicians

Abstract. Performing music at a professional level is probably one of the most complex human accomplishments requiring extensive training periods. The superior skills of musicians are mirrored in plastic adaptations of the brain involving gray and white matter increase in sensory motor and auditory areas and enlargement of receptive fields. Motor disturbances in musicians are common and include mild forms, such as temporary motor fatigue, painful overuse injuries following prolonged practice, anxiety-related motor failures during performances, and more persistent losses of motor control, termed “dynamic stereotypes.” Musician’s dystonia is characterized by a permanent loss of motor control when playing a musical instrument linked to genetic susceptibility and to maladaptive plasticity. In this review article, we argue that these motor failures developing on a continuum from motor fatigue to musician’s dystonia require client tailored treatment and accordingly specific psychological and neurological interventions.

Focal Task-specific Dystonia among Professional Musicians in Latin America

In Response To: Frucht SJ. Focal task-specific dystonia-from early descriptions to a new, modern formulation. Tremor Other Hyperkinet Mov. 2014; 4. doi: 10.7916/D8VD6WHP.

Pain Relief in Cervical Dystonia with Botulinum Toxin Treatment

Dystonia is a neurological disorder characterized by intermittent or sustained muscle contractions that cause abnormal, usually repetitive, movements and postures. Dystonic movements can be tremulous and twisting and often follow a pattern. They are frequently associated with overflow muscle activation and may be triggered or worsened by voluntary action. Most voluntary muscles can be affected and, in the case of the neck muscles, the condition is referred to as cervical dystonia (CD), the most common form of dystonia. The high incidence of pain distinguishes CD from other focal dystonias and contributes significantly to patient disability and low quality of life. Different degrees of pain in the cervical region are reported by more than 60% of patients, and pain intensity is directly related to disease severity. Botulinum toxin (BoNT) is currently considered the treatment of choice for CD and can lead to an improvement in pain and dystonic symptoms in up to 90% of patients. The results for BoNT/A and BoNT/B are similar. The complex relationship between pain and dystonia has resulted in a large number of studies and more comprehensive assessments of dystonic patients. When planning the application of BoNT, pain should be a key factor in the choice of muscles and doses. In conclusion, BoNT is highly effective in controlling pain, and its analgesic effect is sustained for a long time in most CD patients.

Apollo's curse: neurological causes of motor impairments in musicians

Performing music at a professional level is probably one of the most complex human accomplishments. Extremely fast and complex, temporo-spatially predefined movement patterns have to be learned, memorized, and retrieved with high reliability in order to meet the expectations of listeners. Performing music requires not only the integration of multimodal sensory and motor information, and its precise monitoring via auditory and kinesthetic feedback, but also emotional communicative skills, which provide a "speaking" rendition of a musical masterpiece. To acquire these specialized auditory-sensory-motor and emotional skills, musicians must undergo extensive training periods over many years, which start in early childhood and continue on through stages of increasing physical and strategic complexities. Performance anxiety, linked to high societal pressures such as the fear of failure and heightened self-demands, frequently accompanies these learning processes. Motor disturbances in musicians are common and include mild forms, such as temporary motor fatigue with short-term reduction of motor skills, painful overuse injuries following prolonged practice, anxiety-related motor failures during performances (choking under pressure), as well as more persistent losses of motor control, here termed "dynamic stereotypes" (DSs). Musician's dystonia (MD), which is characterized by the permanent loss of control of highly skilled movements when playing a musical instrument, is the gravest manifestation of dysfunctional motor programs, frequently linked to a genetic susceptibility to develop such motor disturbances. In this review chapter, we focus on different types of motor failures in musicians. We argue that motor failures in musicians develop along a continuum, starting with subtle transient degradations due to fatigue, overuse, or performance stress, which transform by and by into more permanent, still fluctuating motor degradations, the DSs, until a more irreversible condition, MD manifests. We will review the epidemiology and the principles of medical treatment of MD and discuss prevention strategies.

Stereotactic neurosurgery for writer's cramp: report of two cases with an overview of the literature

BACKGROUND

Writer's cramp is a specific movement disorder with hand muscle cramps in writing, being classified into focal and action-specific dystonia. Stereotactic surgery, such as thalamotomy and deep brain stimulation (DBS), has been reported for writer's cramp; however, the number of reported cases is still scarce and surgical procedures are also controversial.

OBJECTIVES

In this study, therefore, we present 2 patients who underwent thalamotomy for writer's cramp and systematically review the literature on stereotactic surgery for writer's cramp.

METHODS

Case reports and literature review are presented.

RESULTS

Both patients underwent ventral oral nucleus (Vo) thalamotomy safely. Their symptoms completely disappeared after surgery and did not recur during follow-up periods. In the literature, a total of 31 cases were surgically treated for writer's cramp. Stereotactic surgery included thalamotomy in 25 cases and DBS in 6. The target included the Vo in 17 cases, the ventral intermediate nucleus (Vim) in 3, and both Vo and Vim in 7. Both procedures markedly improved or resolved the symptoms. Transient neurological deficits were observed in 16.0% of patients after thalamotomy.

CONCLUSIONS

The Vo may be the most effective target to treat writer's cramp. Both thalamotomy and DBS are feasible and effective, but thalamotomy would be a better option, especially in younger or high-risk patients.

The sodium leak channel, NALCN, in health and disease

Ion channels are crucial components of cellular excitability and are involved in many neurological diseases. This review focuses on the sodium leak, G protein-coupled receptors (GPCRs)-activated NALCN channel that is predominantly expressed in neurons where it regulates the resting membrane potential and neuronal excitability. NALCN is part of a complex that includes not only GPCRs, but also UNC-79, UNC-80, NLF-1 and src family of Tyrosine kinases (SFKs). There is growing evidence that the NALCN channelosome critically regulates its ion conduction. Both in mammals and invertebrates, animal models revealed an involvement in many processes such as locomotor behaviors, sensitivity to volatile anesthetics, and respiratory rhythms. There is also evidence that alteration in this NALCN channelosome can cause a wide variety of diseases. Indeed, mutations in the NALCN gene were identified in Infantile Neuroaxonal Dystrophy (INAD) patients, as well as in patients with an Autosomal Recessive Syndrome with severe hypotonia, speech impairment, and cognitive delay. Deletions in NALCN gene were also reported in diseases such as 13q syndrome. In addition, genes encoding NALCN, NLF- 1, UNC-79, and UNC-80 proteins may be susceptibility loci for several diseases including bipolar disorder, schizophrenia, Alzheimer's disease, autism, epilepsy, alcoholism, cardiac diseases and cancer. Although the physiological role of the NALCN channelosome is poorly understood, its involvement in human diseases should foster interest for drug development in the near future. Toward this goal, we review here the current knowledge on the NALCN channelosome in physiology and diseases.

Descriptive epidemiology of cervical dystonia

Background

Cervical dystonia (CD), the most common form of adult-onset focal dystonia, has a heterogeneous clinical presentation with variable clinical features, leading to difficulties and delays in diagnosis. Owing to the lack of reviews specifically focusing on the frequency of primary CD in the general population, we performed a systematic literature search to examine its prevalence/incidence and analyze methodological differences among studies.

Methods

We performed a systematic literature search to examine the prevalence data of primary focal CD. Sixteen articles met our methodological criteria. Because the reported prevalence estimates were found to vary widely across studies, we analyzed methodological differences and other factors to determine whether true differences exist in prevalence rates among geographic areas (and by gender and age distributions), as well as to facilitate recommendations for future studies.

Results

Prevalence estimates ranged from 20–4,100 cases/million. Generally, studies that relied on service-based and record-linkage system data likely underestimated the prevalence of CD, whereas population-based studies suffered from over-ascertainment. The more methodologically robust studies yielded a range of estimates of 28–183 cases/million. Despite the varying prevalence estimates, an approximate 2:1 female:male ratio was consistent among many studies. Three studies estimated incidence, ranging from 8–12 cases/million person-years.

Discussion

Although several studies have attempted to estimate the prevalence and incidence of CD, there is a need for additional well-designed epidemiological studies on primary CD that include large populations; use defined CD diagnostic criteria; and stratify for factors such as age, gender, and ethnicity.

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.

Musician's cramp as manifestation of maladaptive brain plasticity: arguments from instrumental differences

Musician's cramp is a task-specific movement disorder that presents itself as muscular incoordination or loss of voluntary motor control of extensively trained movements while a musician is playing the instrument. It is characterized by task specificity and gender bias, affecting significantly more males than females. The etiology is multifaceted: a combination of a genetic predisposition, termed endophenotype, and behavioral triggering factors being the leading features for the manifestation of the disorder. We present epidemiological data from 591 musician patients from our outpatient clinic demonstrating an influence of fine-motor requirements on the manifestation of dystonia. Brass, guitar, and woodwind players were at greater risk than other instrumentalists. High temporospatial precision of movement patterns, synchronous demands on tonic and phasic muscular activation, in combination with fine-motor burdens of using the dominant hand in daily life activities, constitute as triggering factors for the disorder and may explain why different body parts are affected.

Botulinum toxin clinic-based epidemiologic survey of adults with primary dystonia in East china

Background and Purpose:

Primary focal or segmental dystonia is a rare clinical condition. The clinical features of dystonia have not been evaluated in China. We performed a study to investigate the epidemiology of primary dystonia and its clinical variants in an adult population.

Methods:

A Botulinum Toxin Clinic-based study was conducted in the period 18 May through 8 October 2010 in East China. We identified 523 dystonia patients from the Movement disorders and Botulinum Toxin clinic Cases.

Results:

The most common focal dystonia were blepharospasm (59%), cervical dystonia (35%), limb dystonia (3%), oromandibular dystonia (2%) and laryngeal dystonia (1%). Males with primary dystonia were noted to have earlier age of onset. A female predominance was noted for most of the primary dystonias with a male to female ratio (M : F) ranging from 1 : 1.48 to 1 : 3.

Conclusions:

The epidemiological features of dystonia in East China we collected were similar to the report in Japan which contrasts partly with that reported in Europe.

Causes for treatment delays in dystonia and hemifacial spasm: a Canadian survey

BACKGROUND

Dystonia must be accurately diagnosed so that treatment can be administered promptly. However, dystonia is a complex disorder, with variable presentation, which can delay diagnosis.

METHODS

Data were gathered by questionnaire from 866 patients with dystonia or hemifacial spasm (HFS) treated in 14 movement disorders centres in Canada injecting botulinum toxin, to better understand the path to diagnosis, wait times and obstacles to treatment.

RESULTS

Most participants were female (64.1%), mean age was 58 years, and patients consulted an average of 3.2 physicians before receiving a dystonia or HFS diagnosis. Many patients (34%) received other diagnoses before referral to a movement disorders clinic, most commonly "stress" (42.7%). A variety of treatments were often received without a diagnosis. The mean lag time between symptom onset and diagnosis was 5.4 years. After the decision to use botulinum toxin, patients waited a mean of 3.1 months before treatment. The most common diagnoses were cervical dystonia (51.6% of patients), HFS (20.0%) and blepharospasm (9.8%).

CONCLUSIONS

Survey results show that diagnosis of dystonias or of HFS, and therefore, access to treatment, is delayed. An educational program for primary care physicians may be helpful to decrease the time to diagnosis and referral to a specialist centre for treatment.

Early-onset primary dystonia

"Dystonia" is the term used to describe abnormal movements consisting of sustained muscle contractions frequently causing twisting and repetitive movements or abnormal postures. Dystonia is classified partly by age at onset because this helps guide the diagnostic work-up and treatment decisions. This chapter focuses on early-onset (<26 years old) primary dystonia. The history, clinical features, genetics, pathophysiology, diagnosis, and treatment of early-onset primary dystonia are discussed. Special emphasis is placed on DYT1 dystonia, the most common, autosomal-dominant, early-onset, primary dystonia. A diagnostic algorithm is proposed for gene-negative early-onset dystonia, and treatment recommendations for generalized, early-onset dystonia are made.

Adult-onset dystonia

Dystonia is defined as involuntary sustained muscle contractions producing twisting or squeezing movements and abnormal postures. The movements can be stereotyped and repetitive and they may vary in speed from rapid to slow; sustained contractions can result in fixed postures. Dystonic disorders are classified into primary and secondary forms. Several types of adult-onset primary dystonia have been identified but all share the characteristic that dystonia (including tremor) is the sole neurologic feature. The forms most commonly seen in neurological practice include cranial dystonia (blepharospasm, oromandibular and lingual dystonia and spasmodic dysphonia), cervical dystonia (also known as spasmodic torticollis) and writer's cramp. These are the disorders that benefit most from botulinum toxin injections. A general characteristic of dystonia is that the movements or postures may occur in relation to specific voluntary actions by the involved muscle groups (such as in writer's cramp). Dystonic contractions may occur in one body segment with movement of another (overflow dystonia). With progression, dystonia often becomes present at rest. Dystonic movements typically worsen with anxiety, heightened emotions, and fatigue, decrease with relaxation, and disappear during sleep. There may be diurnal fluctuations in the dystonia, which manifest as little or no involuntary movement in the morning followed by severe disabling dystonia in the afternoon and evening. Morning improvement (or honeymoon) is seen with several types of dystonia. Patients often discover maneuvers that reduce the dystonia and which involve sensory stimuli such as touching the chin lightly in cervical dystonia. These maneuvers are known as sensory tricks, or gestes antagonistes. This chapter focuses on adult-onset focal dystonias including cranial dystonia, cervical dystonia, and writer's cramp. The chapter begins with a review of the epidemiology of focal dystonias, followed by discussions of each major type of focal dystonia, covering clinical phenomenology, differential genetics, and diagnosis. The chapter concludes with discussions of the pathophysiology, the few pathological cases published of adult-onset focal dystonia and management options, and a a brief look at the future.

Focal dystonia in musicians: phenomenology, pathophysiology and triggering factors

BACKGROUND

Musician's dystonia is a task-specific movement disorder that manifests itself as a loss of voluntary motor control in extensively trained movements. In many cases, the disorder terminates the careers of affected musicians. Approximately, 1% of all professional musicians are affected. The pathophysiology of the disorder is still unclear. Findings include: (i) reduced inhibition in different levels of the central nervous system, (ii) maladaptive plasticity, e.g. in the somatosensory cortex and in the basal ganglia and (iii) alterations in sensorimotor processing.

METHODS

Review of the literature.

RESULTS

Epidemiological data demonstrated a higher risk for those musicians who play instruments requiring maximal fine-motor skills. For instruments where workload differs across hands, focal dystonia appears more often in the more intensely used hand. In psychological studies, musicians with dystonia had more perfectionist tendencies than healthy musicians. These findings strengthen the assumption that behavioural factors may be involved in the etiology of musician's dystonia. Hereditary factors may play a greater role than previously assumed.

CONCLUSIONS

We propose a heuristic model that may explain the relatively high incidence of focal dystonia in musicians. This model assumes the coactions between a predominantly genetically determined predisposition and intrinsic and extrinsic triggering factors.

Therapeutic challenges in dystonia

Because dystonia can vary in clinical presentation and etiology, proper diagnosis and classification of these disorders are important in making therapeutic decisions. In primary dystonia, treatment is generally geared toward alleviating symptoms rather than curing the underlying condition, therefore severity of contractions, pain, and functional and social impact are also factors to consider in determining if and how to initiate therapy. On the other hand, if a secondary cause is identified, then it is often appropriate to direct treatment toward the underlying disorder. Treatment options include physical and occupational therapy, oral medications, botulinum toxin, and surgery. This article briefly reviews the clinical features, pathophysiology, and classification of dystonia before reviewing current therapeutic options.

Focal hand dystonia in musicians: phenomenology, etiology, and psychological trigger factors

NARRATIVE REVIEW: Musician's dystonia is a task-specific movement disorder, which manifests itself as a loss of voluntary motor control in extensively trained movements. In many cases, the disorder terminates the careers of affected musicians. Approximately 1% of all professional musicians are affected. In the past, focal dystonia (FD) was classified as a psychological disorder. Over time, the problem was classified as a neurological problem. Although the specific pathophysiology of the disorder is still unclear, it appears the etiology is multifactorial. While there may be a family history, neurophysiological, physical, and environmental factors, trauma and stress contribute to the phenotypic development of FD. This manuscript analyzes the evidence supporting the potential contribution of the emotional brain systems in the etiology of focal hand dystonia in musicians. In addition, the psychological findings from a large descriptive study comparing healthy musicians, musicians with dystonia, and musicians with chronic pain. Information about psychogenic characteristics might be used to modify intervention strategies and music instruction to reduce the incidence of musician's dystonia.

Task-specific dystonias: a review

Task-specific dystonias are primary focal dystonias characterized by excessive muscle contractions producing abnormal postures during selective motor activities that often involve highly skilled, repetitive movements. Historically these peculiar postures were considered psychogenic but have now been classified as forms of dystonia. Writer's cramp is the most commonly identified task-specific dystonia and has features typical of this group of disorders. Symptoms may begin with lack of dexterity during performance of a specific motor task with increasingly abnormal posturing of the involved body part as motor activity continues. Initially, the dystonia may manifest only during the performance of the inciting task, but as the condition progresses it may also occur during other activities or even at rest. Neurological exam is usually unremarkable except for the dystonia-related abnormalities. Although the precise pathophysiology remains unclear, increasing evidence suggests reduced inhibition at different levels of the sensorimotor system. Symptomatic treatment options include oral medications, botulinum toxin injections, neurosurgical procedures, and adaptive strategies. Prognosis may vary depending upon body part involved and specific type of task affected. Further research may reveal new insights into the etiology, pathophysiology, natural history, and improved treatment of these conditions.

Community survey of primary dystonia in the city of Kolkata, India

An epidemiological study on dystonia has not been reported from India. As part of a major study to find out the prevalence of major neurological disorders in the large urban city of Kolkata, Eastern India, we planned to determine the prevalence of primary dystonia. The study design was a cross-sectional study of a sample population obtained through stratified random selection and conducted in a two-stage procedure of screening by a nonprofessional team followed by confirmation of screened positive cases by the study neurologist. A total population of 52,377 was screened, and 29 subjects with dystonia were diagnosed. Out of them 23 subjects had primary dystonias [crude prevalence rate (CPR), 43.91/100,000; 95% confidence interval (CI), 28.41-64.81; age-standardized rates to world standard population, 49.06 (95% CI,31.74-72.41)] and all cases were focal type and predominantly of limb dystonia variety. Mean onset of dystonias were earlier in women (43.5 years) as compared to men (46.6 years). Thus our study on primary dystonia shows higher prevalence when compared with that of many studies globally, predominantly of focal type, earlier onset among women, and more cases of limb dystonias when compared with more prominent blepharospasm and cervical dystonias in western reports.

Cervical Dystonia

Cervical dystonia, which is the most common form of focal dystonia, presents with sustained neck spasms, abnormal head posture, head tremor, and pain. One of the interesting and unique features of cervical dystonia is the geste antagoniste. There is not a well-described pathophysiology for cervical dystonia, but several hypotheses report involvement at the central and peripheral level. Treatment options include: oral medical therapy, botulinum toxin injection, and surgery. Oral medical therapy has limited efficacy in control of the symptoms of cervical dystonia. Two types of botulinum toxin, types A and B, are being used for treatment of cervical dystonia, with equivalent benefit. Surgery is an option when other treatments fail or become ineffective. The surgical procedures are brain lesioning, brain stimulation, and peripheral surgical intervention. Several trials are currently ongoing in the United States and Europe to evaluate the efficacy of deep brain surgery in cervical dystonia.

Epidemiology of primary focal dystonias in the western area of Tottori prefecture in Japan: Comparison with prevalence evaluated in 1993

An epidemiological survey of primary focal dystonias in the western area of Tottori Prefecture in Japan was conducted in 2003, and the results were compared with those of a previous survey in 1993. The service-based prevalence of primary focal dystonia was 13.7 per 100,000 population, representing an increase from that found in the 1993 survey. In 1997, botulinum toxin type A was approved for use in Japan to treat blepharospasm, and the increased number of patients now being evaluated and diagnosed with focal dystonias at medical centers throughout Japan may be responsible for this increased prevalence. Prevalence by subtype per 100,000 population was as follows: facial dystonia, 6.5; spasmodic torticollis, 2.0; writer's cramp, 4.4; and other focal dystonias; 0.8. Facial dystonia showed the most marked increase in service-based prevalence among these subtypes.

Prevalence of dystonia in Akita Prefecture in Northern Japan

We investigated the prevalence of dystonia in Akita Prefecture (population was 1,166,967 as of 1 November 2004). The prevalence of primary generalized and focal dystonia is estimated to be 0.68 and 14.4 per 100,000 persons, respectively. Blepharospasm is the most common primary dystonia in this area.

Dystonia

Dystonia is a disorder of involuntary sustained muscle contractions. It is commonly classified by age of onset, distribution of involved body regions, and etiology. The pathophysiolgy of this condition is complex and imperfectly understood. This article reviews the epidemiology, genetics, clinical features, and approach to diagnosis and treatment of dystonia.

Prevalence study of primary dystonia in Iceland

In Iceland, the crude prevalence for all types of primary dystonia was 37.1/10(5) (confidence interval, 30.4-44.9). Focal dystonia had the highest prevalence (31.2/10(5)), followed by segmental (3.1/10(5)), multifocal (2.4/10(5)) and generalized dystonia (0.3/10(5)). Cervical dystonia was the most common focal dystonia (11.5/10(5)), followed by limb dystonia (8.0/10(5)), laryngeal dystonia (5.9/10(5)), blepharospasm (3.1/10(5)), and oromandibular dystonia (2.8/10(5)). The male:female ratio for all patients was 1:1.9 (P=0.0007), and females outnumbered males in all subtypes except oromandibular dystonia. Mean age of onset for all patients was 42.7 years (range, 3-82 years). This prevalence of primary dystonia is higher than in most reported studies, possibly because of more complete ascertainment but the relative frequencies of dystonia subtypes is similar.

A new screening tool for cervical dystonia

BACKGROUND

Family studies of dystonia may be limited in part by small family size and incomplete ascertainment of dystonia in geographically dispersed families. Further, prevalence estimates of dystonia are believed to be underestimates, as most studies are clinic-based and many individuals do not present to a physician or are misdiagnosed. As a low-cost highly sensitive screening tool is needed to improve case detection for genetic and epidemiologic studies, the authors developed the Beth Israel Dystonia Screen (BIDS), a computer-assisted telephone interview.

OBJECTIVE

To evaluate the validity and utility of a computer-assisted telephone interview in screening for cervical dystonia.

METHODS

The BIDS was administered and videotaped neurologic examinations performed on 193 individuals from 16 families with cervical and cranial dystonia. With use of a final rating of definite dystonia, as determined by video review of a systematic neurologic evaluation, as the gold standard, the predictive value of a subset of questions from the BIDS was assessed.

RESULTS

A positive response to at least two of five screening questions had a sensitivity for cervical dystonia of 100% and a specificity of 92%. With use of a positive response to three or more questions, definite dystonia was determined with 81% sensitivity and 97% specificity.

CONCLUSIONS

The Beth Israel Dystonia Screen (BIDS) identifies cervical dystonia with excellent sensitivity and specificity in a family-based sample. The authors recommend the BIDS for family studies, but cross-validation in a population sample is advisable before applying this method to epidemiologic studies.

A 9-year review of dystonia from a movement disorders clinic in Singapore

The clinical features of dystonia have not been evaluated in Southeast Asia. We therefore investigated the clinical spectrum and characteristics of dystonia in Singapore, a multi-ethnic Southeast Asian country comprising 77% Chinese, 14% Malays, and 8% Indians. We identified all dystonia patients from the Movement Disorders database and Botulinum Toxin clinic between 1995 and November 2004. Their medical records were reviewed to verify the diagnosis of dystonia and obtain demographic and clinical data using a standardized data collection form. A total of 119 (73%) patients had primary dystonia whilst 45 (27%) had secondary dystonia. There were 77% Chinese, 9% Malays, and 8% Indians. The most common focal dystonia were cervical dystonia (47%), writer's cramp (32%), and blepharospasm (11%). There was no significant difference in the distribution of dystonia between the different races. Males were noted to have earlier onset of dystonia overall. There was a significant male predominance in primary dystonia overall (M:F 1.6:1, P=0.008) and in the subgroup of focal dystonia (M:F 1.6:1, P=0.037). This contrasts with previous studies that found a female predominance. The role of genetic, hormonal, and environmental factors and their interactions need to be investigated to better understand the gender differences in the occurrence of dystonia.

Prevalence of primary blepharospasm in Sardinia, Italy: A service-based survey

We performed a service-based epidemiological study of primary blepharospasm in the island of Sardinia (Italy). Due to its favorable geographical location, we are confident we will provide reliable data from patients seeking botulinum toxin treatment. A total of 53 patients were assessed. Prevalence was estimated to be 32.2 per 1 million (95% confidence interval, 23.0-40.8). These results are in line with those obtained in other similar surveys, that is, record-based, and performed in various European regions such as Northern England, the Munich area, as well as the Epidemiologic Study of Dystonia in Europe.

Benign Essential Blepharospasm: Risk Factors with Reference to Hemifacial Spasm

BACKGROUND

To identify risk factors associated with benign essential blepharospasm (BEB) with reference to hemifacial spasm (HFS). Persons with BEB and HFS experience similar physical symptoms, yet the two disorders have different etiologies.

METHODS

Patients with BEB (n = 159) or HFS (n = 91) were identified from two large neuro-ophthalmology clinics. Demographic, medical, behavioral, and psychological characteristics were obtained from chart review and a telephonic survey questionnaire.

RESULTS

The average age of BEB and HFS was 66 years. Most patients in both groups were retired, white, and female. BEB patients were more than two times as likely to meet the diagnostic criteria for generalized anxiety disorder than HFS patients (odds ratio, 2.13; 95% confidence interval, 1.22-3.72). There was no difference between the two groups regarding demographics, smoking, a family history of dystonia, Parkinson disease, Bell palsy, Tourette disorder, obsessive compulsive symptoms, history of head trauma, alcohol use, or caffeine consumption.

CONCLUSIONS

As compared to HFS, BEB was significantly more often associated with generalized anxiety disorder. Given the similarity of other clinical features of these two disorders, it is reasonable to conclude that anxiety is a cause not a consequence of BEB. Contrary to previous studies, BEB was not associated with obsessive-compulsive symptoms, head trauma, Parkinson disease, Bell palsy, Tourette disorder, or lack of smoking.

Efficacy and safety of a new Botulinum Toxin Type A free of complexing proteins in the treatment of blepharospasm

NT 201 is a new development of Botulinum Toxin Type A free of complexing proteins. In this double-blind Phase III trial, we compared the efficacy and safety of NT 201 and BOTOX in patients suffering from blepharospasm. Of 304 enrolled patients, 300 patients received study medication (intent-to-treat population), and 256 patients completed the study as planned (per-protocol population). At baseline, patients received a single injection of NT 201 or BOTOX (<or=35 units per eye). No significant differences were found between NT 201 and BOTOX for all efficacy and safety variables three weeks after injection. Both the NT 201 and the BOTOX group showed a decrease in the Jankovic Rating Scale (JRS) sum score signifying an improvement in the symptoms of blepharospasm during this time period. These data show that NT 201* is an effective and safe treatment for patients suffering from blepharospasm.

Epidemiology of primary dystonia

The prevalence estimates for primary dystonia range from two to 50 cases per million for early-onset dystonia and from 30 to 7320 cases per million for late-onset dystonia. From analysis of methodological information from 14 selected studies, we concluded that all studies on the basis of treatment settings or record-linkage systems, and two population-based surveys were probably flawed by incomplete ascertainment; the third population-based study provided the largest prevalence for late-onset dystonia but probably overestimated the prevalence of the disorder. Age and ethnic differences among study populations further biased comparisons of estimates. On the basis of methodologically more robust service-based studies and the likely percentage of underdiagnosis in a given area, more accurate prevalence estimates may be 111 per million for early-onset dystonia in Ashkenazi Jews from New York area, 600 per million for late-onset dystonia in northern England, and 3000 per million for late-onset dystonia in the Italian population over age 50 years.

Prevalence of primary late-onset focal dystonia in the Belgrade population

The aim of this cross-sectional study was to estimate the prevalence of different subtypes of idiopathic focal dystonia in the population of Belgrade (Serbia), Yugoslavia. On December 31, 2001, the crude prevalence of all studied types of dystonia (focal, segmental, and multifocal) in Belgrade was 13.6 per 100,000 population (11.8 per 100,000 for men and 15.2 per 100,000 for women). Type-specific prevalence for focal dystonia was 11.2 per 100,000. The prevalence for cervical dystonia, blepharospasm, writer's cramp and laryngeal dystonia were 5.9 per 100,000, 1.9 per 100,000, 1.9 per 100,000, and 1.1 per 100,000, respectively.

Epidemiology of primary dystonias in Japan: comparison with Western countries

We performed epidemiological studies of primary dystonia in the city of Kyoto. The prevalence was at least 10.1 per 100,000 persons, which was similar to that in Western countries. Facial dystonia was more common than other types, which contrasts with that reported in Europe. Age of onset for both genders was in agreement with that in other countries.

Movement Disorders

This chapter covers five movement disorders: Parkinson's disease, dystonia, tic disorders, Huntington's disease, and essential tremor. These disorders demonstrate many of the most common challenges encountered in the epidemiologic investigation of movement disorders. Each section includes a description of the disease, followed by a review of descriptive studies (disease incidence, prevalence, and mortality studies), and discussion of genetic and environmental risk factors for the disorder. At the end of each section, directions for future studies are discussed.

Benign essential blepharospasm among residents of Olmsted County, Minnesota, 1976 to 1995: an epidemiologic study

PURPOSE

To describe the incidence, patient demographics, and response to treatment of benign essential blepharospasm (BEB) in a population-based cohort.

METHODS

In this epidemiologic study, we searched the Rochester Epidemiology Project database for patients diagnosed with blepharospasm or related disorders between 1976 and 1995. The incident rate denominator was based on a linear interpolation of decennial census data from Olmsted County. The 95% confidence interval for the incidence rate was based on the Poisson distribution.

RESULTS

Olmsted County residents (n = 295) were diagnosed with blepharospasm or related disorders between 1976 and 1995. Of these, 8 patients met the criteria for BEB. The calculated incidence rate of BEB is 1.2 persons per 100,000 population per year (95% CI, 0.37 to 2.02). At the time of BEB diagnosis, the median patient age was 61.5 years, and symptoms had been present for a median of 24 months. Four patients were men and 4 were women. Four of the 8 patients had Meige syndrome. Three of 4 patients treated with oral medications reported symptomatic improvement. Botulinum toxin injection was offered to all patients, but only 4 elected treatment. All who were treated with botulinum toxin had temporary symptomatic improvement. No patient underwent surgical treatment for BEB. Two patients had resolution of symptoms within the follow-up period.

CONCLUSIONS

BEB is a rare disorder. In this small, population-based sample, women and men were affected with equal frequency, and half of patients had lower facial dystonia (Meige syndrome). Only half of patients with BEB elected botulinum toxin injections, and none required surgery. Disease remission occurred in 2 of 8 patients.

The genetics of primary dystonias and related disorders

Dystonias are a heterogeneous group of disorders which are known to have a strong inherited basis. This review details recent advances in our understanding of the genetic basis of dystonias, including the primary dystonias, the 'dystonia-plus' syndromes and heredodegenerative disorders. The review focuses particularly on clinical and genetic features and molecular mechanisms. Conditions discussed in detail include idiopathic torsion dystonia (DYT1), focal dystonias (DYT7) and mixed dystonias (DYT6 and DYT13), dopa-responsive dystonia, myoclonus dystonia, rapid-onset dystonia parkinsonism, Fahr disease, Aicardi-Goutieres syndrome, Hallervorden-Spatz syndrome, X-linked dystonia parkinsonism, deafness-dystonia syndrome, mitochondrial dystonias, neuroacanthocytosis and the paroxysmal dystonias/dyskinesias.

Epidemiology of primary blepharospasm

We review epidemiological data on primary blepharospasm (BSP). There is a large variation in the stated prevalence of BSP, with crude estimates ranging from 16 to 133 per million in different studies. A large proportion of this variability may be the result of differences in physician education on BSP. Age and female gender may increase the risk of developing BSP. The few case-control studies focusing on adult dystonias including BSP showed an increased risk in association with family history of dystonia and/or postural tremor, prior head and face trauma, and prior eye disease (e.g., blepharitis and keratoconjunctivitis), and a decreased risk associated with cigarette smoking. No association was found with age-related medical conditions such as hypertension and diabetes, family history of parkinsonism, and a history of anxiety or depression. Broocks et al. [Am J Psychiatry, 1998;155:555-557] found a significantly higher frequency of obsessive-compulsive symptoms in BSP than hemifacial spasm despite the clinical similarity. Among putative risk factors for BSP, age at onset, female gender, and prior head or face trauma may affect spread of dystonia to adjacent body regions. While limited, the body of epidemiological data support the idea that environmental and familial, possibly genetic, factors may both be important in the etiology of BSP.