Abstract
BACKGROUND: A systematic review of epidemiological studies of primary dystonia from 1985 and 2010 found an overall prevalence of 16.43 per 100,000 (95% CI = 12.09-22.32). METHODS: We performed a systematic review of studies from 2010 and 2022 to determine if there are important differences in epidemiology between these time periods. RESULTS: Nineteen studies were included. Incidence of cervical dystonia, blepharospasm, and oromandibular dystonia were each reported in one study; one study reported incidence for all adult onset idiopathic focal dystonias combined. Using data from 11 studies, we performed random effects meta-analyses of the prevalence of cervical dystonia (9.95 per 100,000; 95% CI = 3.51-28.17), blepharospasm (2.82 per 100,000; 95% CI = 1.12-7.12), laryngeal dystonia (0.40 per 100,000; 95% CI = 0.09-1.83), upper limb dystonia (1.27 per 100,000; 95% CI = 0.36-4.52), oromandibular dystonia (0.57 per 100,000; 95% CI = 0.15-2.15), and idiopathic or inherited isolated dystonia all subtypes combined (30.85 per 100,000; 95% CI = 5.06-187.74). All studies reported more cases of dystonia in females. There was no significant difference in prevalence by subgroup analysis based on time of study publication (1985-2010 vs. 2010-2022). Subgroup analysis of differences in prevalence by dystonia subtype by continent using all studies published (1985-2022) revealed significant regional differences in the prevalence of cervical and laryngeal dystonia. CONCLUSION: The incidence and prevalence of idiopathic or inherited isolated dystonia in the last decade was not significantly different from earlier reports. Population-based studies across multiple geographic areas are needed to obtain a clearer understanding of the epidemiology of this condition.