The relationship between occupation and specific forms of idiopathic adult-onset dystonia

Background: The development of idiopathic adult-onset dystonia (IAOD) in different body parts is associated with specific demographic and clinical characteristics, as well as with specific risk factors. Objective: To investigate whether specific occupations are associated with specific forms of IAOD at onset, namely blepharospasm (BSP), cervical dystonia (CD), and task-specific upper limb dystonia (TS-ULD). Methods: Data from 905 IAOD patients enrolled in the Italian Dystonia Registry were analysed. Each patient was assigned to the corresponding occupational category by specialists in occupational medicine according to the classification of the Italian National Institute of Statistics. Logistic regression models (adjusted for sex, year of birth, Italian geographical areas, and age at dystonia onset) were computed to assess the association between occupation and specific dystonia at onset, using patients who developed focal dystonia in other body parts as controls. Results: Compared to other occupations, trades workers exhibited an increased risk for BSP at onset (OR = 2.6, 95% CI 1.6–4.2), cleaners for CD (OR = 3.4, 95% CI 1.2–9.9), and musicians for TS-ULD (OR = 36.3, 95% CI 11.3–117.1). The longer the duration of employment before the onset of dystonia, the greater the risk of dystonia. Conclusions: We provided novel information indicating that exposure to specific occupations may trigger specific forms of IAOD, namely BSP, CD, and TS-ULD. The associations highlighted by this study may reflect a common pathophysiological mechanism relying on the frequent performance of repetitive movements in a specific body part.