Early-onset primary dystonia.

"Dystonia" is the term used to describe abnormal movements consisting of sustained muscle contractions frequently causing twisting and repetitive movements or abnormal postures. Dystonia is classified partly by age at onset because this helps guide the diagnostic work-up and treatment decisions. This chapter focuses on early-onset (<26 years old) primary dystonia. The history, clinical features, genetics, pathophysiology, diagnosis, and treatment of early-onset primary dystonia are discussed. Special emphasis is placed on DYT1 dystonia, the most common, autosomal-dominant, early-onset, primary dystonia. A diagnostic algorithm is proposed for gene-negative early-onset dystonia, and treatment recommendations for generalized, early-onset dystonia are made.