[Focal dystonia: clinical, etiologic and therapeutic aspects]

Blepharospasm, spasmodic torticoli, and writer's cramp are the most frequently observed forms of focal dystonia. Primary dystonia is often a hereditary condition with a dominant autosomal mode of transmission and variable penetrance. Secondary conditions are generally the expression of a lesion to the basal ganglia due to an iatrogenic cause or exceptionally the inaugural sign of a metabolic disease. The basal ganglia play an important role in the pathophysiology of this reciprocal innervation disorder but progress in genetics may help better understand the different molecular mechanisms involved. Treatment relies on botulin toxin associated with physical therapy depending on the localization. Drug therapy is often disappointing due to minimal efficacy and poor tolerance.