The prevalence of primary dystonia: A systematic review and meta‐analysis

Abstract

Dystonia is a hyperkinetic movement disorder characterized by sustained muscle contractions that produce repetitive movements and abnormal postures. Specific information on the prevalence of dystonia has been difficult to establish because the existing epidemiological studies of the condition have adopted different methodologies for case ascertainment, resulting in widely differing reported prevalence. Medline and Embase databases were searched using terms specific to dystonia for studies of incidence, prevalence, and epidemiology. All population-based studies reporting an incidence and/or prevalence of primary dystonia were included. Sixteen original studies were included in our systematic review. Fifteen studies reported the prevalence of dystonia, including 12 service-based and three population-based studies. We performed a meta-analysis on the results of the service-based studies, and were able to combine data on the prevalence of several dystonia subtypes. From these studies, we calculated an overall prevalence of primary dystonia of 16.43 per 100,000 (95% confidence interval [CI]: 12.09-22.32). The prevalence of dystonia reported in the three population-based studies appears higher than that reported in the service-based studies. Only 1 of the 16 studies reported an incidence of cervical dystonia. This corresponded to a corrected incidence estimate of 1.07 per 100,000 person-years (95% CI: 0.86-1.32). Despite numerous studies on the epidemiology of dystonia, attempting to determine an accurate prevalence of the condition for health services planning remains a significant challenge. Given the methodological limitations of the existing studies, our own prevalence estimate of primary dystonia likely underestimates the true prevalence of the condition.

Botulinum toxin type A versus botulinum toxin type B for cervical dystonia

“…Dystonia is the third most common movement disorder, after Parkinson's disease and essential tremor, with an overall prevalence of 164 per million (Steeves 2012 Focal dystonia is a highly disabling movement disorder, with serious functional and social impairment. At the average age of 40 years, almost half of the patients quit working or retire early due to dystonia, and 10 years later, only 25% of patients are working compared to 62% of the general population (Zoons 2012).…”

Nonmotor symptoms in primary adult‐onset cervical dystonia and blepharospasm

“…According to the involvement of body region, dystonia can be classified into focal, segmental, multifocal, hemidystonia, and generalized dystonia (Albanese et al., 2013). Cervical dystonia (CD) and blepharospasm (BSP) are the most common forms of focal dystonia, with a prevalence of 4.98 per 100 000 and 4.24 per 100 000 separately (Steeves, Day, Dykeman, Jette, & Pringsheim, 2012). …”

The Role of Systematic Reviews and Meta-Analyses of Incidence and Prevalence Studies in Neuroepidemiology

“…The Q statistic provides a p value indicating the presence of heterogeneity and the I 2 statistic provides information on the percentage of heterogeneity that exists. Steeves et al [10] used this method to quantify the amount of heterogeneity present in a recent review on the prevalence of primary dystonia.…”

“…Recent systematic reviews and meta-analyses have explored the incidence and/or prevalence of movement disorders, including Huntington's disease [8], tic disorders [9] and primary dystonia [10], using meta-regression and stratification to establish subgroup differences. For example, in a study of tic disorders, Knight et al [9] used meta-regression to determine whether prevalence estimates differed between boys and girls, finding that boys had a significantly higher prevalence than girls.…”