A family with paroxysmal nonkinesigenic dyskinesia: genetic and treatment issues.

Paroxysmal nonkinesigenic dyskinesia is a condition characterized by attacks of sudden involuntary movements triggered by caffeine or alcohol intake, stress, or fatigue. The paroxysms are usually of the generalized type and may last up to an hour. Described here is a Polish family with this disorder seen in two children and their father. Variable expressivity as well as reduced penetrance of the causative mutation were noteworthy in this kindred. Treatment options included abortive diazepam and prophylactic levetiracetam, with the latter having a more pronounced effect in this family. Favorable response to levetiracetam is probably linked to action of the drug on calcium channels in neurons, muscle cells, or both.