Unravelling of the paroxysmal dyskinesias

Paroxysmal dyskinesias (PxD) refer to a rare group of clinically and genetically heterogeneous disorders presenting with recurrent attacks of abnormal movements, typically dystonia, chorea or a combination thereof, without loss of consciousness. Classically, PxD have been categorised according to their triggers and duration of the attacks, but increasing evidence suggests that there is a certain degree of clinical and genetic overlap and challenges the concept that one phenotype is attributable to one single aetiology. Here we review the increasing spectrum of genetic conditions, as well as of other non-genetic disorders, that might present with PxD, provide criteria for case definition and propose a diagnostic workup to reach a definitive diagnosis, on which treatment is heavily dependent.