Late-onset primary dystonia in Zhejiang province of China: a service-based epidemiological study

Abstract

Dystonia is characterized by sustained muscle contractions, causing repetitive movements and abnormal postures. The epidemiological study of dystonia of Chinese population was limited reported. In this study, we investigated the epidemiology of primary dystonia, and its clinical characteristics in an adult population in China. We identified all dystonia patients from the movement disorders database and botulinum toxin clinic between 2009 and 2013. The medical records were reviewed to verify the diagnosis of dystonia, and demographic and clinical data were collected. A total of 1481 patients with primary dystonia were studied. The most common focal dystonia were blepharospasm (56.4 %), cervical dystonia (36.7 %), limb dystonia (3.4 %), oromandibular dystonia (2.9 %) and laryngeal dystonia (0.6 %). Males with primary dystonia were found to have an earlier age of onset. A female predominance was noted for most of the primary dystonia, with a men to women ratio (M:F) of 1:2.01. The minimum estimate of prevalence of primary dystonia was 27.0 (95 % confidence interval: 25.6-28.3) per million persons in this study. Despite the difference in genetic background and geographic area, the epidemiological features of dystonia in China from our study share most features around the world, such as women dystonia dominance, early-onset age of dystonia with women, etc. But East Asia countries (China and Japan) may share more common features of dystonia.

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

“…The number of patients in the study from the genetically isolated Faroe Islands was small reflecting the size of the community [ 21 ]. Other dystonia prevalence studies excluding Finland reported prevalence of CD between 20 and 248 per million [ 5 , 9 , 10 , 12 – 17 , 19 , 22 , 23 , 26 ] ( Table 2 ). It is possible, that a positive selection bias occurs, when most CD patients in Finland are followed-up in specialized health care.…”

“…Regional variations in dystonia prevalence have been reported previously from other countries. In Japan and China, blepharospasm prevalence has been shown to exceed the prevalence of cervical CD [ 13 , 23 ], while in western countries focal CD is the most common form of dystonia [ 4 , 5 ]. Moreover, in southern parts of Europe, blepharospasm has been reported being more common than in northern parts.…”

Epidemiological, clinical and genetic aspects of adult onset isolated focal dystonia in Ireland

“…Prevalence rates of primary dystonia range from 30 cases per million to 7320 per million [14][15][16][17][18][19]. Prevalence estimates of AOIFD (formerly adult onset primary torsion dystonia) range from 20 to 137 cases per million [16,17,[20][21][22][23]. Genetic heterogeneity and variation in environmental exposures are possible explanations for this wide range [24,25].…”

Association Analysis ofNALCNPolymorphisms rs1338041 and rs61973742 in a Chinese Population with Isolated Cervical Dystonia

“…The possible reason is that the sample size is not enough to discover some SNPs with small effect on the disease according to the author. The prevalence of primary dystonia in China was 27.0 per million persons based on the minimum estimates [ 20 ]. Therefore, the present study had a probability of 80% power to detect genetic effects at an OR of 1.85 under an additive model in our sample (two-sided, P < 0.01) [ 13 ].…”