Sex prevalence of focal dystonias

Sex Differences in Dystonia

BACKGROUND

Prior studies have indicated that female individuals outnumber male individuals for certain types of dystonia. Few studies have addressed factors impacting these sex differences or their potential biological mechanisms.

OBJECTIVES

To evaluate factors underlying sex differences in the dystonias and explore potential mechanisms for these differences.

METHODS

Data from individuals with various types of dystonia were analyzed in relation to sex. Data came from two different sources. One source was the Dystonia Coalition database, which contains predominantly idiopathic adult-onset focal and segmental dystonias. The second source was the MDSGene database, which contains predominantly early-onset monogenic dystonias.

RESULTS

The 3222 individuals from the Dystonia Coalition included 71% female participants and 29% male participants for an overall female-to-male ratio (F:M) of 2.4. This ratio varied according to body region affected and whether dystonia was task-specific. The female predominance was age-dependent. Sex did not have a significant impact on co-existing tremor, geste antagoniste, depression or anxiety. In the 1377 individuals from the MDSGene database, female participants outnumbered male participants for some genes (GNAL, GCH1, and ANO3) but not for other genes (THAP1, TH, and TOR1A).

CONCLUSIONS

These results are in keeping with prior studies that have indicated female individuals outnumber male individuals for both adult-onset idiopathic and early onset monogenic dystonias. These results extend prior observations by revealing that sex ratios depend on the type of dystonia, age, and underlying genetics.

Long-term Efficacy of Bilateral Globus Pallidus Stimulation in the Treatment of Meige Syndrome

OBJECTIVE

This study aimed to investigate the long-term efficacy and prognosis of bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) in patients with benign essential blepharospasm (BEB) and complete Meige syndrome, and to search for the best therapeutic subregion within the GPi.

MATERIALS AND METHODS

Data were collected for 36 patients with Meige syndrome who underwent bilateral GPi-DBS surgery at our hospital between March 2014 and February 2022. Using the Burk-Fahn-Marsden Dystonia Rating Scale (BFMDRS)-Movement (BFMDRS-M) and BFMDRS-Disability (BFMDRS-D), the severity of the symptoms of patients with complete Meige syndrome was evaluated before surgery and at specific time points after surgery. Patients with BEB were clinically evaluated for the severity of blepharospasm using BFMDRS-M, the Blepharospasm Disability Index (BDI), and Jankovic Rating Scale (JRS). Three-dimensional reconstruction of the GPi-electrode was performed in some patients using the lead-DBS software, and the correlation between GPi subregion volume of tissue activated (VTA) and symptom improvement was analyzed in patients six months after surgery. The follow-up duration ranged from six to 99 months.

RESULTS

Compared with preoperative scores, the results of all patients at six months after surgery and final follow-up showed a significant decrease (p < 0.05) in the mean BFMDRS-M score. Among them, the average BFMDRS-M improvement rates in patients with BEB at six months after surgery and final follow-up were 60.3% and 69.7%, respectively, whereas those in patients with complete Meige syndrome were 54.5% and 58.3%, respectively. The average JRS and BDI scores of patients with BEB also decreased significantly (p < 0.05) at six months after surgery and at the final follow-up (JRS improvement: 38.6% and 49.1%, respectively; BDI improvement: 42.6% and 57.4%, respectively). We were unable to identify significantly correlated prognostic factors. There was a significant correlation between GPi occipital VTA and symptom improvement in patients at six months after surgery (r = 0.34, p = 0.025).

CONCLUSIONS

Our study suggests that bilateral GPi-DBS is an effective treatment for Meige syndrome, with no serious postoperative complications. The VTA in the GPi subregion may be related to the movement score improvement. In addition, further research is needed to predict patients with poor surgical outcomes.

Does sex influence the natural history of idiopathic adult-onset dystonia?

BACKGROUND

Several earlier studies showed a female predominance in idiopathic adult-onset dystonia (IAOD) affecting the craniocervical area and a male preponderance in limb dystonia. However, sex-related differences may result from bias inherent to study design. Moreover, information is lacking on whether sex-related differences exist in expressing other dystonia-associated features and dystonia spread.

OBJECTIVE

To provide accurate information on the relationship between sex differences, motor phenomenology, dystonia-associated features and the natural history of IAOD.

METHODS

Data of 1701 patients with IAOD from the Italian Dystonia Registry were analysed.

RESULTS

Women predominated over men in blepharospasm, oromandibular, laryngeal and cervical dystonia; the sex ratio was reversed in task-specific upper limb dystonia; and no clear sex difference emerged in non-task-specific upper limb dystonia and lower limb dystonia. This pattern was present at disease onset and the last examination. Women and men did not significantly differ for several dystonia-associated features and tendency to spread. In women and men, the absolute number of individuals who developed dystonia tended to increase from 20 to 60 years and then declined. However, when we stratified by site of dystonia onset, different patterns of female-to-male ratio over time could be observed in the various forms of dystonia.

CONCLUSIONS

Our findings provide novel evidence on sex as a key mediator of IAOD phenotype at disease onset. Age-related sexual dimorphism may result from the varying exposures to specific age-related and sex-related environmental risk factors interacting in a complex manner with biological factors such as hormonal sex factors.

Dystonias: Clinical Recognition and the Role of Additional Diagnostic Testing

Dystonia is the third most common movement disorder, characterized by abnormal, frequently twisting postures related to co-contraction of agonist and antagonist muscles. Diagnosis is challenging. We provide a comprehensive appraisal of the epidemiology and an approach to the phenomenology and classification of dystonia, based on the clinical characteristics and underlying etiology of dystonia syndromes. We discuss the features of common idiopathic and genetic forms of dystonia, diagnostic challenges, and dystonia mimics. Appropriate workup is based on the age of symptom onset, rate of progression, whether dystonia is isolated or combined with another movement disorder or complex neurological and other organ system eatures. Based on these features, we discuss when imaging and genetic should be considered. We discuss the multidisciplinary treatment of dystonia, including rehabilitation and treatment principles according to the etiology, including when pathogenesis-direct treatment is available, oral pharmacological therapy, chemodenervation with botulinum toxin injections, deep brain stimulation and other surgical therapies, and future directions.

Clinical Implications of Dystonia as a Neural Network Disorder

Isolated dystonia is a neurological disorder of diverse etiology, multifactorial pathophysiology, and wide spectrum of clinical presentations. We review the recent neuroimaging advances that led to the conceptualization of dystonia as a neural network disorder and discuss how current knowledge is shaping the identification of biomarkers of dystonia and the development of novel pharmacological therapies.

Impact of Depression on Cognitive Function and Disease Severity in Idiopathic Cervical Dystonia Patients: One-Center Data in Cross-Sectional Study

Background: Cervical dystonia is a highly disabling hyperkinetic movement disorder with a lot of nonmotor symptoms. One symptom with a high prevalence is depression, which may negatively affect dystonia patients. The aim of the study was to investigate the impact of depression on disease severity and cognitive functions in cervical dystonia patients. Methods: Patients with cervical dystonia were interviewed and divided into two groups, based on the Patient Health Questionnaire-9: those with no depression or mild depressive features and those with moderate, moderately severe, and severe depression. The severity of dystonia and cognitive functions were assessed and compared in both groups. Results: A total of 52 patients were investigated. Self-assessment of the disease was more negative in clinically significant depressive signs group (p = 0.004), with a tendency for patients with clinically significant depressive features to have a slightly higher score on objective dystonia scales (TSUI and TWSTRS), but without statistically significant differences (p = 0.387 and p = 0.244, respectively). Although not statistically significant, a slightly higher MoCA scale score was registered in cervical dystonia patients with clinically insignificant depressive signs. There was a tendency for worse results in the abstraction category in patients with clinically significant depression (p = 0.056). Conclusions: Patients with clinically significant depression have a more negative self-assessment of the disease and perform worse in abstraction tasks.

Botulinum Neurotoxin Therapy in the Clinical Management of Laryngeal Dystonia

Laryngeal dystonia (LD), or spasmodic dysphonia (SD), is a chronic, task-specific, focal movement disorder affecting the larynx. It interferes primarily with the essential functions of phonation and speech. LD affects patients' ability to communicate effectively and significantly diminishes their quality of life. Botulinum neurotoxin was first used as a therapeutic agent in the treatment of LD four decades ago and remains the standard of care for the treatment of LD. This article provides an overview of the clinical application of botulinum neurotoxin in the management of LD, focusing on the classification for this disorder, its pathophysiology, clinical assessment and diagnosis, the role of laryngeal electromyography and a summary of therapeutic injection techniques, including a comprehensive description of various procedural approaches, recommendations for injection sites and dosage considerations.

Sex and gender differences in movement disorders: Parkinson's disease, essential tremor, dystonia and chorea

Sex and gender-based differences in epidemiology, clinical features and therapeutical responses are emerging in several movement disorders, even though they are still not widely recognized. In this chapter, we summarize the most relevant evidence concerning these differences in Parkinson's disease, essential tremor, dystonia and chorea. Indeed, both sex-related biological (hormonal levels fluctuations) and gender-related variables (socio-cultural and environmental factors) may differently impact symptoms manifestation and severity, phenotype and disease progression of movement disorders on men and women. Moreover, sex differences in treatment responses should be taken into account in any therapeutical planning. Physicians need to be aware of these major differences between men and women that will eventually have a major impact on better tailoring prevention, treatment, or even delaying progression of the most common movement disorders.

Specific movement and disability improvements in Burke-Fahn-Marsden Dystonia Rating Scale derived from pallidotomy in refractory patients to medical treatment

BACKGROUND

Dystonia is a movement disorder associated with significant disability and is usually refractory to medical treatment. Pallidotomy may decrease dystonic movements. The aim of this study was to quantify movement and disability improvements through Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS).

METHODS

We carried out a longitudinal clinical study in patients with refractory primary and secondary dystonia, who underwent radiofrequency (RF) unilateral and bilateral lesions on the postero-ventro-lateral globus pallidus internus (GPi), evaluating the outcomes through BFMDRS and variables as age, time of evolution, etiology, body distribution, planned target coordinates, and lesion size, during a mean follow-up time of 35.67 months.

RESULTS

Nine RF pallidotomies were performed on 6 patients, 7 right-sided and 2 left-sided; three patients were treated unilaterally for one occasion, while the others underwent 2 surgeries, including one staged bilateral procedure. Mean BFMDRS scores for movement were 38.5 preoperative and 25.5 postoperative, and for disability were 20.4 preoperative and 17.3 postoperative. We noticed improvement in movement (32.54%, p = 0.001) and disability (17.23%, p = 0.002). There was one right GPi and internal capsule (IC) infarction with contralateral hemiparesis as sequelae.

CONCLUSIONS

RF pallidotomy is an effective and accessible procedure to reduce BFMDRS scores in refractory dystonia if patients are correctly selected by severity, evolution, and disability as determining factors.

Second hit hypothesis in dystonia: Dysfunctional cross talk between neuroplasticity and environment?

One of the great mysteries in dystonia pathophysiology is the role of environmental factors in disease onset and development. Progress has been made in defining the genetic components of dystonic syndromes, still the mechanisms behind the discrepant relationship between dystonic genotype and phenotype remain largely unclear. Within this review, the preclinical and clinical evidence for environmental stressors as disease modifiers in dystonia pathogenesis are summarized and critically evaluated. The potential role of extragenetic factors is discussed in monogenic as well as adult-onset isolated dystonia. The available clinical evidence for a "second hit" is analyzed in light of the reduced penetrance of monogenic dystonic syndromes and put into context with evidence from animal and cellular models. The contradictory studies on adult-onset dystonia are discussed in detail and backed up by evidence from animal models. Taken together, there is clear evidence of a gene-environment interaction in dystonia, which should be considered in the continued quest to unravel dystonia pathophysiology.

Electrophysiological signatures predict clinical outcomes after deep brain stimulation of the globus pallidus internus in Meige syndrome

OBJECTIVE

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been shown to be a safe and effective alternative therapy for ameliorating medically refractory primary Meige syndrome. However, the associations between DBS target position and surrounding electrophysiological properties as well as patients' clinical outcomes remains largely unknown. In a large number of patients, we investigated electrophysiological features around stimulation targets and explored their roles in predicting clinical outcomes following bilateral GPi-DBS.

METHODS

The locations of DBS active contacts along the long axis of the GPi in a standard space were calculated and compared among three groups with different clinical outcomes. The firing rates of individual neurons within the GPi were calculated for each patient and compared across the three groups.

RESULTS

Compared with the bad group (poor clinical outcome), active contacts in the good group (good clinical outcome) and the best group (best clinical outcome) were located in the more posterior GPi. The average firing rates in the good and best groups were significantly higher than in the bad group, and this difference was pronounced within the ventral GPi. For the bad group, the average firing rates were significantly lower in the ventral than in the dorsal GPi.

CONCLUSIONS

This study suggests that DBS of the posterior GPi may produce better clinical outcomes during primary Meige syndrome treatment and that higher GPi neuronal activity, particularly within the ventral part, can be used as a biomarker to guide DBS electrode implantation during surgery.

Mutational spectrum of GNAL, THAP1 and TOR1A genes in isolated dystonia: study in a population from Spain and systematic literature review

OBJECTIVE

We aimed to investigate the prevalence of TOR1A, GNAL and THAP1 variants as the cause of dystonia in a cohort of Spanish patients with isolated dystonia and in the literature.

METHODS

A population of 2028 subjects (including 1053 patients with different subtypes of isolated dystonia and 975 healthy controls) from southern and central Spain was included. The genes TOR1A, THAP1 and GNAL were screened using a combination of high-resolution melting analysis and direct DNA resequencing. In addition, an extensive literature search to identify original articles (published before 10 August 2020) reporting mutations in TOR1A, THAP1 or GNAL associated to dystonia was performed.

RESULTS

Pathogenic or likely pathogenic variants in TOR1A, THAP1 and GNAL were identified in 0.48%, 0.57% and 0.29% of our patients, respectively. Five patients carried the variation p.Glu303del in TOR1A. A very rare variant in GNAL (p.Ser238Asn) was found as a putative risk factor for dystonia. In the literature, variations in TOR1A, THAP1 and GNAL accounted for about 6%, 1.8% and 1.1% of published dystonia patients, respectively.

CONCLUSIONS

There is a different genetic contribution to dystonia of these three genes in our patients (about 1.3% of patients) and in the literature (about 3.6% of patients), probably due the high proportion of adult-onset cases in our cohort. As regards age at onset, site of dystonia onset, and final distribution, in our population there is a clear differentiation between DYT-TOR1A and DYT-GNAL, with DYT-THAP1 likely to be an intermediate phenotype.

Similar Long-Term Clinical Outcomes of Deep Brain Stimulation With Different Electrode Targets for Primary Meige Syndrome: One Institution's Experience of 17 Cases

OBJECTIVE

Deep brain stimulation (DBS) is considered an effective and safe treatment for patients with primary Meige syndrome (MS). Both the subthalamic nucleus (STN) and globus pallidus pars internus (Gpi) have been shown to be optional targets for electrode implantation to improve clinical symptoms, but the relationship between clinical outcomes and target is still unclear. The current study aims to compare the clinical outcomes of DBS with different electrode targets for primary MS.

MATERIALS AND METHODS

We performed a retrospective study to assess the clinical outcomes for 17 consecutive patients with primary MS in Wuhan Union Hospital from January 2016 to September 2019. Six patients were treated by Gpi-DBS and 11 patients were treated by STN-DBS. All patients were assessed before surgery and at the last follow-up after surgery. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) including the movement and disability scales was used to evaluate the dystonia severity of the eyes, the mouth, speech, and swallowing. The median follow-up duration was 30.1 ± 13.1 months (range 6 months-52 months).

RESULTS

In our study, DBS improved the BFMDRS-M scores by 70.52 ± 7.45% and the BFMDRS-D scores by 70.51 ± 8.38% for patients with MS. STN-DBS and Gpi-DBS had similar effects not only on the BFMDRS-M and BFMDRS-D scores, but also on the subitems including eyes, mouth, speech, and swallowing. The stimulation voltage for the Gpi was significantly higher than that for the STN. The improvements were similar in the general anesthesia and local anesthesia groups (p > 0.05).

CONCLUSION

The curative effects of STN-DBS and Gpi-DBS on patients with primary MS are similar. Both the STN and Gpi could be effective targets of DBS for primary MS.

Grey matter changes in Meige syndrome: a voxel-based morphology analysis

To investigate the changes and clinical significance of brain structural abnormalities in patients with Meige syndrome and related depressive symptoms. We retrospectively analysed clinical data, imaging examinations, and Hamilton Depression Rating scale scores in 46 patients with Meige syndrome from January 2017 to January 2019. We compared the Meige syndrome group with the healthy control group, and the definite depression group with the non-definite depression group. Voxel-based morphometry (VBM) was used to compare grey matter (GM) volumes. We conducted two-sample t-tests corrected for subject age and gender. We tested at a level of significance of p < 0.001 with a false discovery rate (FDR) correction. VBM demonstrated decreased GM volume (p < 0.001 and cluster size > 50 voxels) in the left hemisphere in the middle frontal orbital gyrus, temporal pole (superior temporal gyrus) and insula and in the right hemisphere in the temporal pole (middle temporal gyrus), precuneus, inferior parietal, inferior temporal and olfactory cortices in the Meige syndrome group. Comparing VBM-MRI measures in Meige syndrome patients with and without depression, decreased GM volume was found in the left hemisphere in the cuneus and hippocampus and in the right hemisphere in the angular gyrus, middle frontal gyrus and middle occipital gyrus in the definite depression group. Unlike other dystonia studies that have suggested an involvement of the basal ganglia and motor cortex in the pathophysiology of the disorder , we believe that the precuneus is involved in the development of Meige syndrome. Additionally, our findings suggest that the hippocampus plays a role in the pathogenesis of depression in patients with Meige syndrome.

Subthalamic Nucleus Deep Brain Stimulation in Primary Meige Syndrome: A 1-Year Follow-Up Study

OBJECTIVE

To investigate the efficacy of bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) in patients with Meige syndrome.

MATERIALS AND METHODS

Fifteen consecutive patients who underwent STN-DBS at the Peking University People's Hospital between September 2017 and June 2018 were included in this study. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) movement score and the BFMDRS disability score were obtained prior to surgery, and at specific time points after surgery. Patients' sleep status was also assessed before and after surgery.

RESULTS

The BFMDRS movement scores decreased from 15.3 ± 4.6 to 5.2 ± 6.2 after STN-DBS, with a mean improvement of 68.6% (p < 0.05). The BFMDRS disability scores were also significantly decreased, from 6.9 ± 3.3 to 3.5 ± 2.9, with a mean improvement of 51.7% (p < 0.05). The eye, mouth, speech, and swallowing movement scores also decreased significantly after STN-DBS compared to baseline (p < 0.05). The sleep quality of the patients was also improved after surgery.

CONCLUSIONS

These findings demonstrate that the STN is an effective brain target for the treatment of patients with Meige syndrome. STN-DBS was not only able to improve patients' motor symptoms, but also their sleep status.

Treatment of Blepharospasm and Oromandibular Dystonia with Botulinum Toxins

Blepharospasm and oromandibular dystonia are focal dystonias characterized by involuntary and often patterned, repetitive muscle contractions. There is a long history of medical and surgical therapies, with the current first-line therapy, botulinum neurotoxin (BoNT), becoming standard of care in 1989. This comprehensive review utilized MEDLINE and PubMed and provides an overview of the history of these focal dystonias, BoNT, and the use of toxin to treat them. We present the levels of clinical evidence for each toxin for both, focal dystonias and offer guidance for muscle and site selection as well as dosing.

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.

The Prevalence of Dystonic Tremor and Tremor Associated with Dystonia in Patients with Cervical Dystonia

The link between dystonia and tremor has been known for decades, but the question of whether they are two separate illnesses or just different manifestations of one disease with the same pathophysiological background remains unanswered. We distinguish two types of tremor in dystonia: dystonic tremor (DT), which appears on the body part affected by dystonia, and tremor associated with dystonia (TAWD), which appears in locations where the dystonia does not occur. In this study, the frequency of occurrence of different forms of tremor was determined by clinical examination in a group of adult-onset isolated cervical dystonia (CD) patients treated with regular local injections of botulinum toxin A in our department. In total, 120 patients were included in the study, of which 70 (58.3%) had DT of the head. TAWD was, in all 14 cases (11.7%), observed on the upper limbs, in the form of static or intentional tremor. The aim of this study was to point out the presence of TAWD as one of the clinical signs of CD. DT occurred in more than half of the patients and appears to be a relatively common part of the clinical picture in patients with CD.

Sex differences in movement disorders

In a range of neurological conditions, including movement disorders, sex-related differences are emerging not only in brain anatomy and function, but also in pathogenesis, clinical features and response to treatment. In Parkinson disease (PD), for example, oestrogens can influence the severity of motor symptoms, whereas elevation of androgens can exacerbate tic disorders. Nevertheless, the real impact of sex differences in movement disorders remains under-recognized. In this article, we provide an up-to-date review of sex-related differences in PD and the most common hyperkinetic movement disorders, namely, essential tremor, dystonia, Huntington disease and other chorea syndromes, and Tourette syndrome and other chronic tic disorders. We highlight the most relevant clinical aspects of movement disorders that differ between men and women. Increased recognition of these differences and their impact on patient care could aid the development of tailored approaches to the management of movement disorders and enable the optimization of preclinical research and clinical studies.

Long-term treatment of blepharospasm with botulinum toxin A: a service-based study over a 16-year follow-up in southern China

OBJECTIVE

To elucidate the effect of long-term treatment with botulinum toxin A (BTX-A) for blepharospasm. Prevalence data and clinical features in southern China and influencing factors for selecting BTX-A treatment were explored.

METHODS

We collected data retrospectively from 338 consecutive patients diagnosed with blepharospasm over 16 years to assess prevalence data and clinical features. Thereafter, all patients were classified into BTX-A (n = 135) or non-BTX-A (n = 203) treatment groups according to the patients' requests in order to explore the factors influencing whether BTX-A treatment was chosen. Furthermore, dynamic follow-up data were analyzed to evaluate the long-term efficacy in the BTX-A group.

RESULTS

The prevalence was 23.3 per million, with an onset age of 50.3 ± 12.3 years and a female:male ratio of 2.4:1; the most common symptom was excessive blinking (91.2%). The symptom severity and psychological assessment scores were significantly decreased by treatment with BTX-A (p < 0.01), and there was no significant difference in response duration with the prolongation of BTX-A injections. Adverse events occurred 52 times (5.0%) among 1038 injections. The symptom severity and psychological assessment scores and the occurrence of eye-opening difficulty were higher, and medical expenses and the symptom tolerability rate were lower in the BTX-A group than in the non-BTX-A group (p < 0.05).

CONCLUSION

The onset age was earlier than that in Western countries. However, starting BTX-A treatment early is justified, even though a higher dosage was needed to maintain reliable long-term efficacy. Additionally, symptom severity and medical expenses are the primary factors affecting whether patients select BTX-A treatment.

Defining differences in patient characteristics between spasmodic dysphonia and laryngeal tremor

OBJECTIVE

To compare presenting characteristics of patients with adductor spasmodic dysphonia (ADSD), ADSD with laryngeal tremor (ADSD + LT), and laryngeal tremor without ADSD (LT).

DESIGN

Cross-sectional analysis.

METHODS

Patients treated for laryngeal movement disorders (1990-2016) were included. Analysis of variance and chi square tests measured differences in patient characteristics across the three disease groups. Using ADSD as the referent, multivariable logistic regression models were used to determine whether potential risk factors including patient demographics, family history, presence of potential inciting events prior to disease onset, and coprevalent movement disorders were associated with ADSD + LT or LT.

RESULTS

In all, 652 patients with ADSD (n = 377), ADSD + LT (n = 98), and LT (n = 177) were included. ADSD patients were significantly younger than those with ADSD + LT and LT (52.5 ± 13.4, 63.9 ± 11.3, and 69.3 ± 10.5 years, respectively; P < 0.001). Coprevalent movement disorders were more common in ADSD + LT (38.7%) and LT (57.1%) groups than in the ADSD group (11.5%; P < 0.001). Compared to ADSD, patients with ADSD + LT and LT were more likely to develop an additional movement disorder during follow-up. In multivariable analyses, increasing age, female gender, and having a movement disorder at presentation were associated with significantly greater odds of having ADSD + LT or LT when compared to ADSD.

CONCLUSION

ADSD + LT patients demonstrate intermediate gender composition and age distributions between those with ADSD and LT. These findings suggest that ADSD + LT may be a distinct phenotype in the spectrum of laryngeal movement disorders.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:170-176, 2019.

Dystonia

Dystonia is a neurological condition characterized by abnormal involuntary movements or postures owing to sustained or intermittent muscle contractions. Dystonia can be the manifesting neurological sign of many disorders, either in isolation (isolated dystonia) or with additional signs (combined dystonia). The main focus of this Primer is forms of isolated dystonia of idiopathic or genetic aetiology. These disorders differ in manifestations and severity but can affect all age groups and lead to substantial disability and impaired quality of life. The discovery of genes underlying the mendelian forms of isolated or combined dystonia has led to a better understanding of its pathophysiology. In some of the most common genetic dystonias, such as those caused by TOR1A, THAP1, GCH1 and KMT2B mutations, and idiopathic dystonia, these mechanisms include abnormalities in transcriptional regulation, striatal dopaminergic signalling and synaptic plasticity and a loss of inhibition at neuronal circuits. The diagnosis of dystonia is largely based on clinical signs, and the diagnosis and aetiological definition of this disorder remain a challenge. Effective symptomatic treatments with pharmacological therapy (anticholinergics), intramuscular botulinum toxin injection and deep brain stimulation are available; however, future research will hopefully lead to reliable biomarkers, better treatments and cure of this disorder.

Sun exposure is an environmental factor for the development of blepharospasm

BACKGROUND

Adult-onset isolated focal dystonia may present with various phenotypes including blepharospasm and cervical dystonia. Although inherited in an autosomal dominant manner with a markedly reduced penetrance, environmental factors are considered important in disease penetrance and expression. We observed a marked variation by latitude in the reports of the frequency of patients with blepharospasm relative to those with cervical dystonia; we hypothesised that sun exposure is an environmental risk factor for the development of blepharospasm in genetically susceptible individuals.

METHODS

From published clinic cohorts and epidemiological reports, the ratio of the number of cases of blepharospasm to cervical dystonia (phenotype case ratio) at each study site was analysed with regard to latitude and measures of annual insolation. Meta-regression analyses of the phenotype case ratio to these environmental factors were performed.

RESULTS

The phenotype case ratio in 15 eligible study sites over 41° of latitude demonstrated a statistically significant inverse association with latitude (p=0.0004, R(2)=53.5%). There were significant positive associations between the phenotype case ratio and quarter-one (January-March) insolation (p=0.0005, R(2)=53%) and average annual insolation (p=0.003, R(2)=40%).

CONCLUSION

The increase in the blepharospasm: cervical dystonia case ratio with decreasing latitude and increasing insolation suggests that sunlight exposure is an environmental risk factor for the development of blepharospasm (rather than cervical dystonia) in individuals genetically susceptible to adult-onset dystonia.

Bruxism in craniocervical dystonia: a prospective study

AIMS

Bruxism pathophysiology remains unclear, and its occurrence has been poorly investigated in movement disorders. The aim of this study was to compare the frequency of bruxism in patients with craniocervical dystonia vs. normal controls and to determine its associated clinical features.

METHOD

This is a prospective-control study. A total of 114 dystonic subjects (45 facial dystonia, 69 cervical dystonia) and 182 controls were included. Bruxism was diagnosed using a hetero-questionnaire and a clinical examination performed by trained dentists. Occurrence of bruxism was compared between the different study populations. A binomial logistic regression analysis was used to determine which clinical features influenced bruxism occurrence in each population.

RESULTS

The frequency of bruxism was significantly higher in the dystonic group than in normal controls but there was no difference between facial and cervical dystonia. It was also higher in women than in men. Bruxism features were similar between normal controls and dystonic patients except for a higher score of temporomandibular jaw pain in the dystonic group.

DISCUSSION

The higher frequency of bruxism in dystonic patients suggests that bruxism is increased in patients with basal ganglia dysfunction but that its nature does not differ from that seen in bruxers from the normal population.

Age-Related Sexual Dimorphism in Temporal Discrimination and in Adult-Onset Dystonia Suggests GABAergic Mechanisms

Background

Adult-onset isolated focal dystonia (AOIFD) presenting in early adult life is more frequent in men, whereas in middle age it is female predominant. Temporal discrimination, an endophenotype of adult-onset idiopathic isolated focal dystonia, shows evidence of sexual dimorphism in healthy participants.

Objectives

We assessed the distinctive features of age-related sexual dimorphism of (i) sex ratios in dystonia phenotypes and (ii) sexual dimorphism in temporal discrimination in unaffected relatives of cervical dystonia patients.

Methods

We performed (i) a meta-regression analysis of the proportion of men in published cohorts of phenotypes of adult-onset dystonia in relation to their mean age of onset and (ii) an analysis of temporal discrimination thresholds in 220 unaffected first-degree relatives (125 women) of cervical dystonia patients.

Results

In 53 studies of dystonia phenotypes, the proportion of men showed a highly significant negative association with mean age of onset (p < 0.0001, pseudo-R² = 59.6%), with increasing female predominance from 40 years of age. Age of onset and phenotype together explained 92.8% of the variance in proportion of men. Temporal discrimination in relatives under the age of 35 years is faster in women than men but the age-related rate of deterioration in women is twice that of men; after 45 years of age, men have faster temporal discrimination than women.

Conclusion

Temporal discrimination in unaffected relatives of cervical dystonia patients and sex ratios in adult-onset dystonia phenotypes show similar patterns of age-related sexual dimorphism. Such age-related sexual dimorphism in temporal discrimination and adult-onset focal dystonia may reflect common underlying mechanisms. Cerebral GABA levels have been reported to show similar age-related sexual dimorphism in healthy participants and may be the mechanism underlying the observed age-related sexual dimorphism in temporal discrimination and the sex ratios in AOIFD.

A Clinical Profile of 125 Patients with Writer's Cramp

BACKGROUND

The characteristics of writer's cramp (WC) may vary according to native languages and scripts. We report the clinical profile of a large cohort of patients with WC from India.

METHODS

A chart review of 125 patients (F:M = 16:109) with WC seen over 10 years at the National Institute of Mental Health and Neurosciences (NIMHANS), India.

RESULTS

The mean age of patients was 36.8 ± 14.3, the mean age at onset (AAO) of symptoms was 31.5 ± 2.7 and the mean duration of difficulty in writing was 5.3 ± 6.3. The most common presenting complaint while writing was pain in the forearm (56%), followed by tremulousness of hand (28.8%) and abnormal posturing of hand (15.2%). Along with writing difficulty, 5.6% had difficulty in typing. The mean AAO of writing difficulty was significantly earlier in women than in men (22.8 ± 3.5 vs. 32.8 ± 4.2 years, p < 0.001). While writing, excessive extension (41.6%) of wrist was the most common abnormality, followed by excessive flexion (37.6%) and extension (19.2%) of index finger.

CONCLUSIONS

Women with WC have a significantly earlier age of onset than men. Excessive extension of wrist with flexion of thumb and index finger were the most common abnormalities noted in WC.

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 phenomenology and natural history of idiopathic lower cranial dystonia

Background

Many patients with lower cranial dystonia (LCrD) are misdiagnosed, and recognition of this condition by general practitioners and dental health professionals is limited.

Methods

We define the phenomenology and natural history of idiopathic LCrD, presenting in 41 patients with the disorder, the largest series of these patients reported to date.

Results

Phenomenology of dystonia included lower cranial and pharyngeal involvement, jaw opening and jaw closing dystonia, and tongue dystonia. Of 25 newly described patients, 72% (18) were female, average age at onset was 56 years, and delay before correct diagnosis was 3.8 years (0-25 years, median 2 years). Eleven patients (44%) reported a precipitating event, the most common of which was recent dental work. Geste antagonistes were found in 18 patients (72%). Response to treatment was mixed, indicating an unmet therapeutic need.

Conclusions

Idiopathic LCrD is often missed and institution of effective therapy is often delayed. The clinical features and natural history of LCrD are similar to other forms of focal dystonia.

Electronic supplementary material

The online version of this article (doi:10.1186/2054-7072-1-3) contains supplementary material, which is available to authorized users.

Cervical dystonia: about familial and sporadic cases in 88 patients

Cervical dystonia (CD) affects the musculature of the neck in a focal way or associated to other parts of the body. The aim of this study was to identify clinical differences between patients with dystonia patients without family history and with family history (sporadic). Eighty-eight patients with CD were recruited in a Movement Disorders Clinic between June of 2008 and June of 2009. Only patients with no etiological diagnosis were accepted for analysis. The age of onset of symptoms was later in patients with focal and segmental dystonia than in patients with generalized dystonia (p<0.001). The severity of symptoms was higher in patients with sporadic dystonia than in familial patients (p<0.01). Generalized cases were more severe in patients with a family history (p<0.01). Sporadic patients had higher levels of pain than familial cases (p<0.05). We expect soon to present the results of genetic analyzes of these patients.

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.

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.

Secondary dystonia in a botulinum toxin clinic: clinical characteristics, neuroanatomical substrate and comparison with idiopathic dystonia

The analysis of patients with secondary dystonia has been valuable to explore the anatomical, pharmacological and physiological bases of this disorder. The goal of this study is to compare the clinical characteristics of patients with primary and secondary dystonia and analyze the neuroanatomical bases of a subgroup of patients with lesion-induced dystonia. We identified patients evaluated in our Botulinum Toxin Clinic from 1/2000 to 7/2009 with an ICD code for "dystonia". Medical records of all subjects were reviewed, recording demographic, clinical, therapeutic and neuroimaging data. A total of 230 patients were included in the study. Idiopathic/primary dystonia was diagnosed in 162 and secondary dystonia in 58, while in 10 the etiology was uncertain. We found a female predominance (2.4:1 and 1.9:1 for primary and secondary dystonia, respectively). The cervical region was most commonly affected in primary dystonia and the limbs in secondary cases. The age at presentation was higher in primary (54.4 ± 14.1) than secondary (49 ± 17.9) dystonia. Among patients with secondary dystonia, a focal lesion was the presumed etiology in 32, with localizing diagnostic studies available in 16. The most common lesions were strokes involving the corticospinal pathway. All of those patients exhibited limb dystonia, except one with cervical dystonia following a thalamic infarct. In conclusion, primary and secondary dystonias are more prevalent in women, suggesting a sex-related predisposition to the development of this movement disorder. Lesion-induced dystonia most frequently involves the limbs and is caused by lesions in the cerebral cortex and subcortical white matter.

Efficacy and safety of incobotulinumtoxinA (NT 201, Xeomin) in the treatment of blepharospasm-a randomized trial

IncobotulinumtoxinA (NT 201, Xeomin) is a highly purified botulinum neurotoxin type A formulation, free from complexing proteins. A randomized, placebo-controlled, double-blind trial of efficacy and safety compared incobotulinumtoxinA (up to 50 U per eye) to placebo administered in a single treatment session to patients with blepharospasm. All patients had documented satisfactory response to 2 previous treatments with botulinum neurotoxin type A other than incobotulinumtoxinA and had Jankovic Rating Scale severity subscores ≥ 2. Patients (n = 109) were randomized in a 2:1 ratio to incobotulinumtoxinA or placebo and followed up to 20 weeks; 94% completed the study. A significant difference was observed in the primary efficacy variable (change in Jankovic Rating Scale severity subscore rated by an independent rater 6 weeks following treatment), favoring incobotulinumtoxinA by 1.0 point (95% CI [0.5-1.4]; P < .001). Functional impairment, as measured by the Blepharospasm Disability Index, improved by 0.5 points (95% CI [0.2-0.7]; P = .002) compared with placebo. There was a strong correlation between the 2 scale scores. In addition, all secondary outcome measures favored incobotulinumtoxinA. Patients rated the mean therapeutic effect of incobotulinumtoxinA significantly better than placebo (P < .001). Adverse events were reported in 70.3% of incobotulinumtoxinA patients and 58.8% of placebo patients. Eyelid ptosis (18.9% vs 5.9%), dry eye (18.9% vs 11.8%), and dry mouth (14.9% vs 2.9%) occurred most frequently. Tolerability was rated good/very good by 91.9% of incobotulinumtoxinA versus in 85.2% of placebo patients. In conclusion, incobotulinumtoxinA was well tolerated and was associated with statistically significant and clinically relevant reductions in blepharospasm severity and functional impairment.

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.

The entity of jaw tremor and dystonia

BACKGROUND

Jaw tremor in the context of dystonia is not well recognized.

METHOD

We describe 7 women (average onset age 70) with jaw tremor and dystonia.

RESULTS

All had features of primary dystonia. Applying MDS criteria for tremor, 3 had "dystonic jaw tremor"; 4 had "jaw tremor associated with dystonia". Drugs were unhelpful. Botulinum toxin injections proved effective in 1 case.

CONCLUSION

We propose the entity of "jaw tremor and dystonia". It is distinct from jaw tremor due to other causes including Parkinson's disease and essential tremor.

Secondary motor disturbances in 101 patients with musician's dystonia

OBJECTIVE

Musician's focal dystonia is usually considered to be task specific but secondary motor disturbances have been reported also. We carried out a detailed evaluation of the incidence of these secondary motor problems in 101 patients.

METHOD

Symptoms were assessed using clinical histories, neurological examinations and observation of instrumental manoeuvres.

RESULTS

53.5% of patients reported secondary motor disturbances in activities other than playing their main instrument, with the onset delayed in some cases by up to 12 years from the awareness of dystonic symptoms. 46.5% suffered from simple, 19.8% from complex and 33.7% from progressive cramps. Plucked string players (guitarists) mainly suffered from simple cramps while keyboardists more frequently displayed the progressive form. In all patients, symptoms were focal, and the type of cramp was unrelated to the severity of the perceived symptoms. Those patients playing a second instrument similar to their main instrument showed symptoms which worsened to a higher degree than those playing either only one instrument or whose second instrument was different.

CONCLUSIONS

Longer follow-up assessments may reveal secondary motor symptoms that are not visible over shorter examination periods. Therefore, a thorough evaluation of everyday life motor activities should be considered in any clinical and treatment protocol. We speculate that the avoidance of movements that are similar to the main affected task may be of help in limiting symptoms. Consequently, focal dystonia may be considered more movement than task specific.

Clinical profile of various sub-types of writer's cramp

We profiled 141 consecutive patients of writer's cramp (WC). Simple WC (n=108) had a mean (SD) disease duration of 3.65 (2.7) years and a severity score of 2.8 (0.91) by Burke-Fahn-Marden (BFM) scale (handwriting score: 0-4 ), whereas complex WC (n=33) had a disease duration of 5.8 (2.81) years and severity score of 3.6 (0.52). Compared with focal WC, generalized WC cases had longer disease duration, severer disability, and were older. Mirror dystonia was seen in 65 patients (46.1%). Co-existent Meige's syndrome (n=4) and cervical dystonia (n=6) were seen. Some patients had abnormal posturing of the neck (n=5) and of the oromandibular region (n=3) only while writing. Those receiving botulinum toxin fared significantly better than those on oral therapy, at 1 month post treatment.

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.

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.