Focal dystonia: clinical, etiologic and therapeutic aspects.

Blepharospasm, spasmodic torticoli, and writer's cramp are the most frequen tly observed forms of focal dystonia. Primary dystonia is often a hereditar y condition with a dominant autosomal mode of Transmission and variable pen etrance. Secondary conditions are generally the expression of a lesion to t he basal ganglia due to an iatrogenic cause or exceptionally the inaugural sign of a metabolic disease. The basal ganglia play an important role in th e pathophysiology of this reciprocal innervation disorder but progress in g enetics may help better understand the different molecular mechanisms invol ved. Treatment relies on botulin toxin associated with physical therapy dep ending on the localization. Drug therapy is often disappointing due to mini mal efficacy and poor tolerance.