Epidemiology and outcome of cervical dystonia (spasmodic torticollis) in Rochester, Minnesota

Topological alterations in white matter anatomical networks in cervical dystonia

BACKGROUND

Accumulating neuroimaging evidence indicates that patients with cervical dystonia (CD) have changes in the cortico-subcortical white matter (WM) bundle. However, whether these patients' WM structural networks undergo reorganization remains largely unclear. We aimed to investigate topological changes in large-scale WM structural networks in patients with CD compared to healthy controls (HCs), and explore the network changes associated with clinical manifestations.

METHODS

Diffusion tensor imaging (DTI) was conducted in 30 patients with CD and 30 HCs, and WM network construction was based on the BNA-246 atlas and deterministic tractography. Based on the graph theoretical analysis, global and local topological properties were calculated and compared between patients with CD and HCs. Then, the AAL-90 atlas was used for the reproducibility analyses. In addition, the relationship between abnormal topological properties and clinical characteristics was analyzed.

RESULTS

Compared with HCs, patients with CD showed changes in network segregation and resilience, characterized by increased local efficiency and assortativity, respectively. In addition, a significant decrease of network strength was also found in patients with CD relative to HCs. Validation analyses using the AAL-90 atlas similarly showed increased assortativity and network strength in patients with CD. No significant correlations were found between altered network properties and clinical characteristics in patients with CD.

CONCLUSION

Our findings show that reorganization of the large-scale WM structural network exists in patients with CD. However, this reorganization is attributed to dystonia-specific abnormalities or hyperkinetic movements that need further identification.

The Impact of Non-Motor Symptoms on Quality of Life in Cervical Dystonia

Cervical dystonia (CD) is characterized by cranial muscle overactivity leading to abnormal intermittent or continuous posturing of the head. Nowadays, the treatment of patients suffering from this condition focuses principally on the motor component of the disorder, certainly the invaliding part; however, it leaves out the non-motor one that has a similarly invalidated effect on the quality of the subject's life. This review was conducted on studies investigating the impact of non-motor symptoms on levels of quality of life. We searched on the PubMed, EMBASE and Web of Science databases and screening references of included studies and review articles for additional citations. From an initial 150 publications, we included only five studies that met the search criteria. The results showed that anxiety, depression, pain and sleep quality have a great influence on patients' health and on the outcome of the disease. Future studies should focus more on investigating the non-motor components of CD as an integral part of the clinical management of dystonic patients in order to improve their well-being.

Risk factors for the development of degenerative cervical myelopathy: a review of the literature

Degenerative cervical myelopathy (DCM) encompasses various pathological conditions causing spinal cord (SC) impairment, including spondylosis (multiple level degeneration), degenerative disc disease (DDD), ossification of the posterior longitudinal ligament (OPLL), and ossification of the ligamentum flavum (OLF). It is considered the most common cause of SC dysfunction among the adult population. The degenerative phenomena of DDD, spondylosis, OPLL and OLF, is likely due to both inter-related and distinct factors. Age, cervical alignment, and range of motion, as well as congenital factors such as cervical cord-canal mismatch due to congenital stenosis, Klippel-Feil, Ehler-Danlos, and Down syndromes have been previously reported as potential factors of risk for DCM. The correlation between some comorbidities, such as rheumatoid arthritis and movement disorders (Parkinson disease and cervical dystonia) and DCM, has also been reported; however, the literature remains scare. Other patient-specific factors including smoking, participation in contact sports, regular heavy load carrying on the head, and occupation (e.g. astronauts) have also been suggested as potential risk of myelopathy development. Most of the identified DCM risk factors remain poorly studied however. Further researches will be necessary to strengthen the current knowledge on the subject, especially concerning physical labors in order to identify patients at risk and to develop an effective treatment strategy for preventing this increasing prevalent disorder.

A metabolomic study of cervical dystonia

INTRODUCTION

Cervical dystonia is the most common of the adult-onset focal dystonias. Most cases are idiopathic. The current view is that cervical dystonia may be caused by some combination of genetic and environmental factors. Genetic contributions have been studied extensively, but there are few studies of other factors. We conducted an exploratory metabolomics analysis of cervical dystonia to identify potentially abnormal metabolites or altered biological pathways.

METHODS

Plasma samples from 100 cases with idiopathic cervical dystonia and 100 controls were compared using liquid chromatography coupled with mass spectrometry-based metabolomics.

RESULTS

A total of 7346 metabolic features remained after quality control, and up to 289 demonstrated significant differences between cases and controls, depending on statistical criteria chosen. Pathway analysis revealed 9 biological processes to be significantly associated at p < 0.05, 5 pathways were related to carbohydrate metabolism, 3 pathways were related to lipid metabolism.

CONCLUSION

This is the first large scale metabolomics study for any type of dystonia. The results may provide potential novel insights into the biology of cervical dystonia.

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.

Disease Progression of Idiopathic Cervical Dystonia in Spite of Improvement After Botulinum Toxin Therapy

Aim of the Study: To demonstrate general progression of symptoms in cervical dystonia (CD) on the one hand and improvement of some special symptoms on the other hand after botulinum toxin (BoNT) therapy. Methods: 74 patients with idiopathic CD under continuous treatment in a BoNT outpatient department with at least three injections, completed a short questionnaire. They were asked whether pain, increased muscle tone and tension, reduced mobility of the head, abnormal head position, head tremor, or other symptoms had been present at the onset of BoNT-therapy and which symptoms were present at the time of recruitment. Patients had to rate actual severity of CD in percent of the severity of CD at the onset of BoNT-therapy. The TSUI score was determined by the treating physician. Blood samples were taken to analyze induction of neutralizing antibodies. Results: Mean improvement of CD reported by the patients and scored by the physician was about 50%. The frequency of all symptoms increased with duration of therapy. The symptom most frequently improved was abnormal head position. The longer the time span between onset of symptoms and onset of BoNT-therapy was, the higher was the actual TSUI score and the lower the improvement reported. Twelve patients had positive antibody tests. Conclusions: Patients experience a progression of CD, but recognize improvement of abnormal head position due to BoNT-therapy. The longer patients have been without BoNT- therapy, the poorer is the long-term outcome independent on duration of BoNT treatment. Therefore BoNT-therapy should be initiated as early as possible.

Spatial and egocentric mental rotation in patients with cervical dystonia

Mental rotation has attracted the interest of cognitive research on dystonia, but at the moment, contrasting data are available on whether this complex cognitive ability is impaired in the disorder. Here, we assessed spatial and egocentric mental rotation in patients with cervical dystonia (CD). Patients with CD and healthy controls were required to perform a letter rotation task (spatial mental rotation) and to judge laterality of front-facing and back-facing human images (egocentric mental rotation). CD patients were selectively impaired on letter rotation, whereas they did not differ from controls when judging laterality of both front-facing and back-facing bodies. These findings support the view according to which neural circuits involved in spatial processing are dysfunctional in CD.

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.

Effective botulinum toxin injection guide for treatment of cervical dystonia

The aim of this study was to elucidate the distribution of the accessory nerve within the sternocleidomastoid muscle (SCM) to aid identifying the optimum sites for botulinum neurotoxin (BoNT) injections and applying chemical neurolysis. Thirty SCM specimens from 15 Korean cadavers were used in this study. Sihler's staining was applied to 10 of the SCM specimens. Transverse lines were drawn in 20 sections to divide the SCM into 10 divisions vertically, and a vertical line was drawn into the medial and lateral halves from the mastoid process to the sternoclavicular joint. The most densely innervated areas were 5/10-6/10 and 6/10-7/10 along the lateral and medial parts of the muscle, respectively. We suggest injecting BoNT in the medial region 6/10-7/10 along the SCM prior to injecting in the lateral region 5/10-6/10 along the muscle to ensure safe and effective treatment. Clin. Anat. 33:192-198, 2020. © 2019 Wiley Periodicals, Inc.

Head Tremor in Cervical Dystonia

Objective:

To compare the clinical characteristics, natural history, and therapeutic outcome of patients with cervical dystonia (CD) with head tremor (HT+) and without head tremor (HT-).

Methods:

We prospectively evaluated 114 consecutive patients of CD over a 9-month period with a detailed questionnaire. Chi-square and t-tests were employed for statistical analysis.

Results:

Seventy-eight (68.4%) patients had head tremor and 27 of them (34.6%) had tremor as one of the first symptoms. Age at onset of symptoms were similar in HT+ and HT- groups; however there was a higher prevalence in women in the former group (66.7% vs. 41.7%; p=0.01). HT+ patients had more frequent positive family history of essential-like hand/head tremor (21.8% vs. 5.5%; p<0.05), associated neck pain (92.3% vs. 77.8%; p<0.05), and essential-like hand tremor (40% vs. 8.3%; p<0.001). They also appeared to have more frequent history of preceding head/neck trauma (14.1% vs. 8.3%), frequent head rotation (88.5% vs. 69.4%) and antecollis (12.8% vs. 5.5%) but less often head tilt (37.2% vs. 47.2%) and gestes antagonistes (60.2% vs. 75%) than the HT- patients; however these differences were not statistically significant. The frequency of prior psychiatric illnesses, the incidence of dystonias in other parts of the body, frequency of retrocollis and shoulder elevation, and spontaneous remission were similar in the two groups.

Conclusions:

Head tremor is common in CD and is more commonly associated with hand tremor and family history of tremor or other movement disorders. This supports a possible genetic association between CD and essential tremor (ET). Linkage studies are required to evaluate the genetic association between CD and ET.

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

INTRODUCTION

Runner's dystonia has previously been described in small series or case reports as a lower limb, task-specific dystonia. We have occasionally encountered this disorder and recognized the same phenomenon in non-runners regularly engaging in lower limb exercise. We wished to characterize the syndrome further, including outcomes, treatment, and the diagnostic usefulness of electrophysiology.

METHODS

We conducted a retrospective review and follow-up survey of adults seen at Mayo Clinic (1996-2015) with task-specific dystonia arising after prolonged repetitive lower limb exercise. The findings were compared to all 21 previously reported cases of runner's dystonia.

RESULTS

We identified 20 patients with this condition, 13 runners and seven non-runner athletes. Median age at dystonia onset was in mid-adulthood. Correct diagnosis was delayed by a median of 3.5 years in runners and 1.6 years in non-runners, by which time more than one-third of patients had undergone unsuccessful invasive procedures. Most patients had dystonia onset in the distal lower limb. Dystonia was task-specific with exercise at onset but progressed to affect walking in most. Sensory tricks were reported in some. Surface EMG was consistent with task-specific dystonia in nine patients. Botulinum toxin, levodopa, clonazepam, trihexyphenidyl, and physical therapy provided modest benefit to some, but all patients remained substantially symptomatic at last follow up.

CONCLUSIONS

Repetitive exercise dystonia is task-specific, confined to the lower limb and occasionally trunk musculature. It tends to be treatment-refractory and limits ability to exercise. Diagnosis is typically delayed, and unnecessary surgical procedures are common. Surface EMG may aid the diagnosis.

A mixed treatment comparison to compare the efficacy and safety of botulinum toxin treatments for cervical dystonia

A systematic pair-wise comparison of all available botulinum toxin serotype A and B treatments for cervical dystonia (CD) was conducted, as direct head-to-head clinical trial comparisons are lacking. Five botulinum toxin products: Dysport^® (abobotulinumtoxinA), Botox^® (onabotulinumtoxinA), Xeomin^® (incobotulinumtoxinA), Prosigne^® (Chinese botulinum toxin serotype A) and Myobloc^® (rimabotulinumtoxinB) have demonstrated efficacy for managing CD. A pair-wise efficacy and safety comparison was performed for all toxins based on literature-reported clinical outcomes. Multi-armed randomized controlled trials (RCTs) were identified for inclusion using a systematic literature review, and assessed for comparability based on patient population and efficacy outcome measures. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) was selected as the efficacy outcome measurement for assessment. A mixed treatment comparison (MTC) was conducted using a Bayesian hierarchical model allowing indirect comparison of the interventions. Due to the limitation of available clinical data, this study only investigated the main effect of toxin treatments without explicitly considering potential confounding factors such as gender and formulation differences. There was reasonable agreement between the number of unconstrained data points, residual deviance and pair-wise results. This research suggests that all botulinum toxin serotype A and serotype B treatments were effective compared to placebo in treating CD, with the exception of Prosigne. Based on this MTC analysis, there is no significant efficacy difference between Dysport, Botox, Xeomin and Myobloc at week four post injection. Of the adverse events measured, neither dysphagia nor injection site pain was significantly greater in the treatment or placebo groups.

Selective peripheral denervation for cervical dystonia: long-term follow-up

OBJECTIVE

61 procedures with selective peripheral denervation for cervical dystonia were retrospectively analysed concerning surgical results, pain, quality of life (QoL) and recurrences.

METHODS

The patients were assessed with the Tsui torticollis scale, Visual Analogue Scale (VAS) for pain and Fugl-Meyer scale for QoL. Evaluations were performed preoperatively, early postoperatively, at 6 months, then at a mean of 42 (13-165) months. All patients underwent electromyogram at baseline, which was repeated in cases who presented with recurrence of symptoms after surgery.

RESULTS

Six months of follow-up was available for 55 (90%) of the procedures and late follow-up for 34 (56%). The mean score of the Tsui scale was 10 preoperatively. It improved to 4.5 (p<0.001) at 6 months, and 5.3 (p<0.001) at late follow-up. VAS for pain improved from 6.5 preoperatively to 4.2 (p<0.001) at 6 months and 4 (p<0.01) at late follow-up. The Fugl-Meyer score for QoL improved from 43.3 to 46.6 (p<0.05) at 6 months, and to 51.1 (p<0.05) at late follow-up. Major reinnervation and/or change in the dystonic pattern occurred following 29% of the procedures, and led in 26% of patients to reoperation with either additional denervation or pallidal stimulation.

CONCLUSIONS

Selective peripheral denervation remains a surgical option in the treatment of cervical dystonia when conservative measures fail. Although the majority of patients experience a significant relief of symptoms, there is a substantial risk of reinnervation and/or change in the pattern of the cervical dystonia.

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.

A retrospective study to assess resource utilization in patients with cervical dystonia in the United Kingdom

PURPOSE

Cervical dystonia (CD) is a hypertonic condition caused by damage to the central nervous system. Very few studies have assessed the overall economic burden of the disease. The objective of this study was to describe the utilization of health care resources of patients with CD in the UK primary care setting, using a large population-based database.

PATIENTS AND METHODS

Adults with a first diagnosis of CD between January 1, 2007 and January 31, 2011, who were registered to a general practitioner (GP) practice contributing to The Health Improvement Network (THIN), were included. Sociodemographic and clinical characteristics were assessed at the time of diagnosis. Health care resource utilization and pharmacological treatment were investigated at the end of the first and second year after diagnosis.

RESULTS

Overall, 4,024 newly diagnosed patients with CD were identified, with average age at diagnosis of 45 years old; 65.3% were female. Depression in the year prior to diagnosis was the most common comorbidity. Primary care utilization was high in the first year, with 99.2% of patients visiting their GP (on average 6.2 times), and 43% visiting a nurse (on average 2.5 times). Patients were most commonly referred to an orthopedic surgeon, and 15.9% reported at least one physiotherapy visit. In the second year, utilization was similar. Prescriptions of at least one of the investigated treatments were found in 82.0% and 45.3%, in the first and second year, respectively.

CONCLUSION

Findings suggest a high number of new CD cases are being identified in primary care, but not all will be referred to secondary care. Health care resource utilization was compared with that of all patients registered in THIN, which is representative of the UK, and the adjusted usage of primary care resources was found to be similar to that of the THIN population.

The physical, social and emotional aspects are the most affected in the quality of life of the patients with cervical dystonia

OBJECTIVE

Describe the functional, clinical and quality of life (QoL) profiles in patients with cervical dystonia (CD) with residual effect or without effect of botulinum toxin (BTX), as well as verify the existence of correlation between the level of motor impairment, pain and QoL.

METHOD

Seventy patients were assessed through the Craniocervical dystonia questionnaire-24 (CDQ-24) and the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS).

RESULTS

The greater the disability, pain and severity of dystonia, the worse the QoL (p<0.0001). Greater severity relates to greater disability (p<0.0001). Pain was present in 84% of the sample, being source of disability in 41%. The most frequent complaints were: difficulty in keeping up with professional and personal demands (74.3%), feeling uneasy in public (72.9%), hindered by pain (68.6%), depressed, annoyed or bitter (47.1%), lonely or isolated (32.9%).

CONCLUSION

The physical, social and emotional aspects are the most affected in the QoL of these patients.

Pallidal Deep Brain Stimulation in Cervical Dystonia: Clinical Outcome in Four Cases

Objective:

Report on the clinical results following bilateral globus pallidus interna deep brain stimulation in four patients (one female and three males) with severe cervical dystonia, mean age 48 years (range 37-67).

Methods:

All four patients had failed extensive medical and botulinum toxin treatment. The mean duration of the disease was nine years (range 4-15 years). Patients were assessed pre and postoperatively using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Preoperatively, the mean TWSTRS total score was 43.2 (range 28-60.5). Posteroventral pallidal deep brain stimulators were inserted using MRI and microelectrode recording guidance. Last follow-up was 15 months for the four patients.

Results:

Mean reduction in the TWSTRS total scores at last follow- up was 73% (range 61- 85%). Improvement in pain occurred soon after deep brain stimulation surgery. Motor improvement was delayed and prolonged over several months. Frequent adjustment in the stimulation parameters was necessary in the first three months.

Conclusion:

Bilateral pallidal stimulation is effective in management of selected cases of intractable cervical dystonia.

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.

Torticollis

Torticollis refers to a twisting of the head and neck caused by a shortened sternocleidomastoid muscle, tipping the head toward the shortened muscle, while rotating the chin in the opposite direction. Torticollis is seen at all ages, from newborns to adults. It can be congenital or postnatally acquired. In this review, we offer a new classification of torticollis, based on its dynamic qualities and pathogenesis. All torticollis can be classified as either nonparoxysmal (nondynamic) or paroxysmal (dynamic). Causes of nonparoxysmal torticollis include congenital muscular; osseous; central nervous system/peripheral nervous system; ocular; and nonmuscular, soft tissue. Causes of paroxysmal torticollis are benign paroxysmal; spasmodic (cervical dystonia); Sandifer syndrome; drugs; increased intracranial pressure; and conversion disorder. The description, epidemiology, clinical presentation, evaluation, treatment, and prognosis of the most clinically significant types of torticollis follow.

Satisfaction with botulinum toxin treatment: a cross-sectional survey of patients with cervical dystonia

OBJECTIVE

Botulinum toxin is widely utilized as a first-line therapy for cervical dystonia (CD). Numerous studies have demonstrated the efficacy and safety of this treatment, but little data exist on patient satisfaction. To address this question, a structured patient survey was conducted in Germany, France, the US, and Canada (n = 136 patients with CD).

METHODS

Specific information was collected on the patients' current and prior botulinum toxin treatment cycles and their overall quality-of-life (including completion of the Cervical Dystonia Impact Profile-58 [CDIP-58]).

RESULTS

Patients rated the mean onset of action for their previous injection as 3.8 days, with peak effect at 3.6 weeks and a decline in effects at 9.5 weeks. While most patients were satisfied with their current therapy, only 50.7% were very satisfied, 42.6% were somewhat satisfied, and 6.6% not at all satisfied with their current therapy. Patient satisfaction was lowest just prior to injection and highest at the time of peak effect. Approximately 45% of patients reported that they would prefer a treatment cycle of ≤10 weeks. The mean patient rating of current state of health was above 50 on a visual analog scale from 0 (low) to 100 (high). CDIP-58 results indicated that patients continued to have symptoms on all domains.

CONCLUSIONS

Botulinum toxin is generally very effective for the treatment of CD. However, this survey indicates that patient satisfaction typically declines prior to re-injection, and many patients may prefer an injection interval of less than the standard 12 weeks. While the survey was based on subjective patient recollections, and the degree to which patient satisfaction is attributable to the control of neurological symptoms remains unclear, prospective studies are clearly warranted to confirm the time course of patient satisfaction and to determine the optimal treatment parameters with botulinum toxins.

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.

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.

Stimulated muscle force assessment of the sternocleidomastoid muscle in humans

The aim of this study was to configure a force assessment device and determine potential testing protocols for quantitative evaluation of human neck muscles. The study design consisted of non-randomized control trials, with repeated measures; data from 12 normal subjects were obtained. Several apparatuses were designed, constructed and tested, i.e. single or short trains of supramaximal stimuli were used to activate sternocleidomastoid muscles in a seated position with strain gauges (6.2% variability with double-pulse stimulations) or in supine positions with load cells (5.2% variability with similar activation). Using a final configuration, maximum elicited peak forces were 1742 +/- 323 g for single-pulse and 3976 +/- 484 g for double-pulse stimulations (n = 12). There were no significant differences in maximum recorded peak torques between sessions per individual. Yet, detectable muscle activities were simultaneously recorded in the contralateral sternocleidomastoid muscles. This non-invasive, quantitative assessment approach has novel value for determining treatment efficacy, disease progression, and/or approach has novel value for determining determining treatment efficacy, disease progression, and/or relative distribution of muscle strength in patients with abnormal neck muscle function.

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.

Cervical dystonia: disease profile and clinical management

Cervical dystonia, the most common focal dystonia, frequently results in cervical pain and disability as well as impairments affecting postural control. The predominant treatment for cervical dystonia is provided by physicians, and treatment can vary from pharmacological to surgical. Little literature examining more conservative approaches, such as physical therapy, exists. This article reviews the etiology and pathophysiology of the disease as well as medical and physical therapist management for people with cervical dystonia.

The entity of young onset primary cervical dystonia

Primary cervical dystonia is typically an adult onset condition with symptom onset usually in the fifth and sixth decade. Young onset (<28 years) is uncommon. We report 76 patients with cervical dystonia as a presenting or predominant feature, with disease onset before the age of 28. Male to female ratio was 1.24:1 and the mean onset age was 21 (3-28) years. A family history of tremor and/or dystonia was noted in 26.3%. Depression and anxiety attacks were present in 23.7%. Prior injury or surgery involving the neck was noted in 17.1%. 23 (30.3%) experienced spontaneous partial or complete remissions within the first 5 years of onset, but all relapsed. Cervical dystonia was predominantly rotational torticollis. 30% developed extra-nuchal dystonia and tremor affecting contiguous parts but in only one there was spread to affect the legs. All 15 patients tested for the DYT1 gene were negative. 74% responded favorably to botulinum toxin injections, whereas none of the 13 patients treated with L-Dopa preparations had a beneficial response. The distinctive features of this entity are discussed.

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.

Disturbed egocentric space representation in cervical dystonia

In addition to visual spatial input, vestibular and proprioceptive signals are used in judging the egocentric space. We asked whether the abnormal head posture of patients with cervical dystonia (CD) is associated with distortions of their internal spatial reference frame. The perception of subjective straight-ahead (SSA) was tested under various conditions in 28 CD patients and in matched controls. They were asked to direct a laser pointer to the position that they believed to be "straight ahead" relative to their bodies' orientation (body-centered spatial perception). Body-independent visual spatial perception was assessed with different neuropsychological tests. CD patients had a greater deviation of the subjective straight ahead, indicating body-centered visual spatial perception, than controls. No effects were seen in body-independent visual spatial perception. Patients with CD are impaired in body-centered, egocentric spatial perception, but not in body-independent, allocentric spatial perception.

Association between male gender and pediatric essential tremor

Approximately 5% of new essential tremor (ET) cases arise during childhood. The goal of the current report was to examine the possible association between male gender and pediatric ET, using data from 95 pediatric ET cases seen at three medical centers (two in the United States and one in Spain). The odds of ET in our sample of cases were threefold higher in boys compared to girls. Whether this association between male gender and pediatric ET represents a selection bias or a true gender-mediated biological difference in disease expression is not known, although some data support the latter possibility.

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.

Alexithymia is no risk factor for exacerbation in spasmodic torticollis patients

OBJECTIVE

To assess whether alexithymia is a risk factor for exacerbation in spasmodic torticollis (ST).

METHODS

ST patients (2 x 10) with high vs. low alexithymia scores (mean score on the 20-item Toronto Alexithymia Scale [TAS-20]=69.2 vs. 28.7) were compared on physiological, motor and subjective responses to a cognitive and an emotional laboratory stressor. Changes in sustained abnormal head/shoulder positions and maximum range of motion (ROM) of the cervical spine were kinematically quantified. Skin conductance level (SCL), nonspecific skin conductance fluctuations (NS.SCF), heart rate (HR) and skin temperature (T) were measured.

RESULTS

High alexithymia had no effect on the abnormal head posture or movements, but high-alexithymic ST patients showed generally increased levels of autonomic arousal (more NS.SCF, higher SCL; analysis of variance [ANOVA]: P=.016 and P=.051, respectively) under all experimental conditions. When ST symptom severity (TSUI-score) was partialled out, these group differences were somewhat reduced (analysis of covariance [ANCOVA]: P=.052 and P=.143).

CONCLUSIONS

High alexithymia did not lead to increased abnormal head movements to stressors, but may result in a subtle increase in tonic level of sympathetic activity.

Orthopedic and neurological complications of cervical dystonia--review of the literature

Cervical dystonia is the most frequent form of focal dystonia. Further, cervical dystonia can occur as a feature of segmental or generalized dystonias and cerebral palsy. Treatment with botulinum toxin to relieve pain and improve functional and psychological outcome is effective, but expensive. However, pharmacoeconomic studies evaluating treatment and disease costs have not taken into consideration the long-term complications of cervical dystonia. Here we present a review of the medical literature on orthopedic and neurological complications arising from cervical dystonia, including cervical spine degeneration, spondylosis, disk herniation, vertebral subluxations and fractures, radiculopathies and myelopathies. In summary, complications are more often reported in generalized dystonia and cerebral palsy than in focal dystonia. The prevalence is not well established, published estimations go from 18 to 41% in selected populations. Awareness of the frequent occurrence of complications and screening for symptoms of radiculomyelopathy in patients with dystonia is essential to avoid irreversible spinal cord damage. Complications of cervical dystonia need to be taken into consideration when weighting risks and calculating costs of the disease and its treatment.

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.

Fracture of the odontoid process complicating tardive dystonia

We report on a 57-year-old woman with frequent and powerful retrocollis. The involuntary movements combined with rheumatoid arthritis and osteoporosis led to a fracture of the axial odontoid process. Neurologists with a focus on movement disorders should screen for diseases putting the patient at risk for spinal lesions and consider early treatment.

Botulinum toxin therapy for cervical dystonia

Botulinum toxin revolutionized the treatment of cervical dystonia. In contrast to systemically active medications, the effect of botulinum toxin results from selective administration to weaken muscles involved in the dystonic posturing of the head. This article reviews the pathophysiologic basis of symptoms in cervical dystonia and how botulinum toxin alleviates them. Other therapeutic options are reviewed for comparison. This article discusses strategies for maximizing the clinical benefit of botulinum toxin in this disorder and reviews muscle selection and identification with electromyography.

High psychiatric comorbidity in spasmodic torticollis: a controlled study

Disturbed body image and negative self-referent cognitions caused by the postural disfigurement of the head are regarded as the main reason for elevated depression scores in spasmodic torticollis (ST), but this factor was never controlled for. We therefore compared 48 patients with ST and 48 patients with alopecia areata (AA) who were matched for age, sex, and body image dissatisfaction. Psychiatric diagnoses were based on a structured psychiatric interview (SCID-I). Results of patients with ST and AA were compared with a matched sample of the representative German population. Odds ratios to develop psychiatric comorbidity for patients with ST compared with patients with AA were significantly increased throughout nearly all assessed DSM-IV categories. Logistic regression analysis showed that (1) depressive coping and (2) belonging to the group of patients with ST correlated with a significantly higher rate of current psychiatric diagnosis. We conclude that high psychiatric comorbidity in ST is unlikely to be a mere consequence of chronic disease and disfigurement.

Focal and segmental primary dystonia in north-western Germany--a clinico-genetic study

OBJECTIVES

To determine the frequency of familial focal and segmental dystonias in a large patient cohort with primary dystonia from north-western Germany.

MATERIALS AND METHODS

In this study, 130 patients with focal or segmental dystonia were examined and a family history was obtained. Whenever possible, affected relatives were examined (a total of 789 first-degree relatives). Data on disease duration, age at disease onset and age of the patients were investigated by Student's t-test and a segregation analysis was performed by Weinberg's proband method.

RESULTS

Age at onset of disease was significantly later in the blepharospasm group. Only in the writer's cramp group were women outnumbered by men. A positive family history was found in 15 of the 130 index patients (11.5%). None of 102 index patients tested carried the GAG deletion in the DYT1 gene.

CONCLUSIONS

In accordance with previous series our study provides evidence that primary focal dystonia may have a genetic etiology, most probably caused by an autosomal dominant trait with reduced penetrance.

Cervical dystonia pathophysiology and treatment options

Dystonia is a syndrome of sustained involuntary muscle contractions, frequently causing twisting and repetitive movements or abnormal posturing. Cervical dystonia (CD) is a form of dystonia that involves neck muscles. However, CD is not the only cause of neck rotation. Torticollis may be caused by orthopaedic, musculofibrotic, infectious and other neurological conditions that affect the anatomy of the neck, and structural causes. It is estimated that there are between 60,000 and 90,000 patients with CD in the US. The majority of the patients present with a combination of neck rotation (rotatory torticollis or rotatocollis), flexion (anterocollis), extension (retrocollis), head tilt (laterocollis) or a lateral or sagittal shift. Neck posturing may be either tonic, clonic or tremulous, and may result in permanent and fixed contractures. Sensory tricks ('geste antagonistique') often temporarily ameliorate dystonic movements and postures. Commonly used sensory tricks by patients with CD include touching the chin, back of the head or top of the head. Patients with CD are classified according to aetiology into two groups: primary CD (idiopathic--may be genetic or sporadic) or secondary CD (symptomatic). Patients with primary CD have no evidence by history, physical examination or laboratory studies (except primary dystonia gene) of any secondary cause for the dystonic symptoms. CD is a part of either generalised or focal dystonic syndrome which may have a genetic basis, with an identifiable genetic association. Secondary or symptomatic CD may be caused by central or peripheral trauma, exposure to dopamine receptor antagonists (tardive), neurodegenerative disease, and other conditions associated with abnormal functioning of the basal ganglia. In the majority of patients with CD, the aetiology is not identifiable and the disorder is often classified as primary. Unless the aetiological investigation reveals a specific therapeutic intervention, therapy for CD is symptomatic. It includes supportive therapy and counselling, physical therapy, pharmacotherapy, chemodenervation [botulinum toxin (BTX), phenol, alcohol], and central and peripheral surgical therapy. The most widely used and accepted therapy for CD is local intramuscular injections of BTX-type A. Currently, both BTX type A and type B are commercially available, and type F has undergone testing. Pharmacotherapy, including anticholinergics, dopaminergic depleting and blocking agents, and other muscle relaxants can be used alone or in combination with other therapeutic interventions. Surgery is usually reserved for patients with CD in whom other forms of treatment have failed.

A pharmacoeconomic evaluation of botulinum toxin in the treatment of spasmodic torticollis

We performed a prospective study in 21 patients to evaluate the cost of treatment of spasmodic torticollis (cervical dystonia) before and after botulinum toxin type A (BTA) treatment and to assess the impact of BTA treatment on quality of life. Data were recorded for the analysis over a period starting 8 months before and ending 7.2 +/- 0.2 months (mean +/- SEM) after the first injection of BTA. All patients received at least two BTA injections (2.9 +/- 0.2 injections per patient). We studied direct medical costs (drugs, outpatient and inpatient visits, diagnostic procedures, physiotherapy), clinical effects of BTA (clinical rating scale and patient's global assessment), quality of life (French version of the Nottingham Health Profile [NHP]), and adverse reactions. Costs associated with the treatment of spasmodic torticollis before the first BTA injection were 479 +/- 143 French Francs (FF)/patient/month (97 +/- 29 US $/pt/mo). During BTA treatment, costs were 1,126 +/- 147 FF/pt/mo (228 +/- 30 US $/pt/mo), including a mean cost of BTA of 771 +/- 131 FF/pt/mo (157 +/- 27 US $/pt/mo). Treatment with BTA significantly decreased clinical symptoms of spasmodic torticollis and improved the emotional, social, and pain-related domains of the quality of life assessment. Botulinum toxin type A treatment increases the cost of treating spasmodic torticollis but improves quality of life in terms of pain, social, and psychologic functioning in patients with spasmodic torticollis.

Post-traumatic cervical dystonia: a distinct entity?

BACKGROUND/OBJECTIVE

The incidence of head/neck trauma preceding cervical dystonia (CD) has been reported to be 5-21%. There are few reports comparing the clinical characteristics of patients with and without a history of injury. Our aim was to compare the clinical characteristics of idiopathic CD (CD-I) to those with onset precipitated by trauma (CD-T).

METHODS

We evaluated 114 consecutive patients with CD over a 9-month period. All patients were interviewed using a detailed questionnaire and had a neurological examination. Their clinical charts were also reviewed.

RESULTS

Fourteen patients (12%) had mild head/neck injury within a year preceding the onset of CD. Between the two groups (CD-I and CD-T), the gender distribution (F:M of 3:2), family history of movement disorders (32% vs. 29%), the prevalence of gestes antagonistes (65% vs. 64%), and response to botulinum toxin were similar. There were non-specific trends, including an earlier age of onset (mean ages 43.3 vs. 37.6), higher prevalence of neck pain (86% vs. 100%), head tremor (67% vs. 79%), and dystonia in other body parts (23% vs. 36%) in CD-T.

CONCLUSIONS

CD-I and CD-T are clinically similar. Trauma may be a triggering factor in CD but this was only supported by non-significant trends in its earlier age of onset.

Do the same genes predispose to Gilles de la Tourette syndrome and dystonia? Report of a new family and review of the literature

Gilles de la Tourette syndrome (TS) and idiopathic focal torsion dystonia are both movement disorders in which the pathologic process is thought to arise within the basal ganglia. However, despite their possible functional links, they are clinically distinct and are generally considered to have different underlying etiologies. There are several reports in the literature that suggest a relationship between eye winking tics, excessive blinking, and blepharospasm and a report of the coexistence of tics and dystonia. We describe a three-generation family in which TS and dystonias cosegregate. In total, eight patients were affected, five with dystonia and three with TS/facial tics. One of the patients with historic evidence of dystonia subsequently died of motor neuron disease. The identification of this family further strengthens the evidence in favor of an etiologic relationship between some cases of Gilles de la Tourette syndrome and focal dystonia.

Doxorubicin chemomyectomy as a treatment for cervical dystonia: histological assessment after direct injection into the sternocleidomastoid muscle

The sternocleidomastoid muscle (SCM) is one of the major muscles involved in producing abnormal head position in cervical dystonia patients. This study tested whether doxorubicin chemomyectomy, direct injection of doxorubicin into the SCM to permanently remove muscle fibers, has the potential to be a nonsurgical, permanent treatment for cervical dystonia. The right SCM of rabbits was injected with either 1 or 2 mg doxorubicin. Animals were sacrificed 1-2 months postinjection. The SCM was prepared for histological examination of muscle fiber loss and fiber type composition. In all cases, direct injection of doxorubicin resulted in significant decreases in total muscle cross-sectional areas ranging from 75% up to 98%. Individual myofiber cross-sectional areas were smaller than normal after 2 mg doxorubicin treatment, but similar to normal fiber size after 1 mg doxorubicin. There were increased numbers of myofibers that expressed slow and neonatal myosin heavy chain isoforms in these remaining muscle fibers compared to the untreated SCM on the contralateral side. Developmental myosin heavy chain (MHC) was also present in 53% of the remaining myofibers of the treated muscles. The fiber type composition of muscles contralateral to the doxorubicin injections was compared to the fiber type composition of SCM from normal, untreated controls; no difference was seen in the proportions of fast, slow, and neonatal MHC fiber types in these SCM muscles. In summary, the direct injection of doxorubicin into the SCM resulted in significant muscle loss. This supports the use of doxorubicin chemomyectomy as a potential permanent, nonsurgical treatment for cervical dystonia.

Muscle fiber type compartmentalization and expression of an immature myosin isoform in the sternocleidomastoid muscle of rabbits and primates

The sternocleidomastoid muscle is located in the neck and is both a neck rotator and flexor. Cervical dystonia, a focal dystonia disorder, is characterized by forceful involuntary contraction of a group of neck muscles, usually including the sternocleidomastoid. Little is known about the fiber type composition, fiber type compartmentalization and innervation patterns in this muscle in rabbit and primates. Sternocleidomastoid muscles from rabbit and monkey were analyzed for muscle fiber type composition and number, muscle fiber cross-sectional area and patterns of innervation. The sternocleidomastoid muscle was composed of two distinct regions, or compartments, with different fiber type compositions: an outer or superficial region composed of mostly type 2 myofibers and an inner deep region composed of both type 2 and type 1 myofibers. Neonatal myosin heavy chain isoform was detected in approximately 25% of the myofibers in both regions of the muscle. Neuromuscular junctions were located in seven endplate bands approximately 1-3 cm apart throughout the length of the muscle. There is clear evidence of anatomical subdivisions within this muscle. Not only is there variation in fiber type composition between superficial and deep regions of the muscle, but unlike most other mature skeletal muscles, it continues to express neonatal myosin heavy chain isoform in the adult. The motor program for neck movements is extremely complex, and the histological complexity plays a role in allowing for a continuum of movements of the head and neck, from maintenance of posture to rapid head movements.

Dystonia and dyskinesia

Dystonia is defined as a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures. Tardive dyskinesia (TD), estimated to occur in 30% of patients treated with neuroleptics, encompasses a broad spectrum of hyperkinesias associated with exposure to these drugs. Dystonia is one of the most common expressions of tardive dyskinesia. This article aims to provide an overview of classification, phenomenology, epidemiology, genetics, pathophysiology, neuropsychologic aspects, and treatment of these two conditions.

Ethnic variation in the clinical expression of idiopathic torsion dystonia

Although childhood, limb-onset idiopathic torsion dystonia (ITD) is at increased prevalence among Jews, and Ashkenazi Jews with this form of ITD show linkage disequilibrium for a unique haplotype, little else is known about phenotypic or genetic variation in ITD among ethnic groups. We assessed clinical features in 786 ITD patients and determined the relative frequencies of various clinical forms of ITD in the major ethnic groups. Several differences in age-at-onset and site-at-onset distributions among groups were demonstrated. As expected, Ashkenazi Jews had an earlier age-at-onset distribution than did non-Jewish Caucasians. In the early-onset group, Jews were less likely to have cervical onset and more likely to have onset in the limbs than were non-Jewish Caucasians (p < 0.01). Among late-onset cases, Jews had less cervical onset and more cranial onset than did non-Jewish Caucasians (p < 0.01). African-Americans showed suggestive differences in both age at onset and site at onset as compared with the two caucasian groups, with an intermediate age at onset, a deficit of leg onset, and an excess of cranial and larynx onset. Subgroups of non-Jewish Caucasians showed no significant differences from each other. The observed ethnic variations in age at onset and site at onset of ITD suggest population differences in disease-causing alleles or loci. However, environmental influences on expression of ITD can not be excluded.