The paroxysmal dyskinesias (PD) are a group of movement disorders characterized by attacks of hyperkinesia with intact consciousness. Paroxysmal dyskinesia is a rare disorder, however the number of individuals it affects remains unclear. There are three different subtypes of PD that include paroxysmal kinesigenic dyskinesia (PKD), paroxysmal nonkinesigenic dyskinesia (PNKD), and paroxysmal exercise-induced dyskinesia (PED). Other neurological diseases have similar symptoms to PD, such as epilepsy and Parkinson's. The different subtypes make accurate and quick diagnosis of PD challenging. Thus, PD is often under reported and misdiagnosed, making it difficult to accurately study its prevalence in human populations. Onset of PD is usually in late childhood to early adolescence. New drug regimens help treat symptoms of PD, but no cure for the disorder is known.

Reference
Wiki: Paroxysmal kinesigenic dyskinesia