Phenotypic spectrum of musician's dystonia: A task-specific disorder?

Background: Musician's dystonia (MD) is traditionally considered a sporadic and task-specific movement disorder. Methods: The phenotypic spectrum of the disorder was studied in 116 patients suffering from MD including videotaping. Results: Based on the movement disorders observed, we categorized our patients into two different groups: (i) 65 patients with isolated MD, that is only present when playing the instrument and (ii) 51 patients with MD and one or more additional features of primary dystonia independent of MD (complex MD). Patients with a positive family history of movement disorders had an increased risk to develop complex MD [odds ratio = 4.80; 95% confidence interval: 1.94-11.92; P = 0.001]. Discussion: In previous studies, we recently identified 22 relatives with different types of movement disorders in the families of 28 MD patients. Taken together, our results further support a genetic contribution to MD with a broad individual and familial phenotypic spectrum consisting of MD, other dystonias and even other, non-dystonic movement disorders.