Paroxysmal dyskinesias

BACKGROUND - Paroxysmal dyskinesias are a heterogenous group of disorders that are characterized by the sudden onset of a variety of abnormal movements out of a background of normal motor activity. REVIEW SUMMARY - Paroxysmal dyskinesias can be classified into four basic varieties: paroxysmal kinesigenic dyskinesia, paroxysmal nonkinesigenic dyskinesia, paroxysmal exertion-induced dyskinesia, and paroxysmal hypnogenic dyskinesia. Most cases are idiopathic and familial, but sporadic cases and symptomatic cases as a result of a number of different causes are well described. The familial cases are inherited in an autosomal dominant fashion, and the gene loci for some have been described. These disorders may belong to an ever- increasing family of episodic neurological disorders that are caused by a dysfunction of ion channels (channelopathies). CONCLUSIONS - Paroxysmal dyskinesias can be idiopathic or symptomatic. The identification of distinct genetic loci will lead to a new genetic classification and to a better understanding of the idiopathic disorders.