Phatophysiology of Paroxysmal Dykinesias; Paroxysmal Movement Disorders - A Practical, Concise Guide

Paroxysmal dyskinesias are a group of hyperkinetic movement disorders characterized by episodes of dystonia, chorea, athetosis, and ballism that appear isolated or in combination without loss of consciousness. We can differentiate various forms of paroxysmal dyskinesia based on genotypic and phenotypic features: Paroxysmal kinesigenic dyskinesia, paroxysmal non-kinesigenic dyskinesia, and paroxysmal exercise-induced dyskinesia. However, all disorders display common traits, such as the paroxysmal nature and the presence of triggering factors. The episodic nature of these diseases suggests that they result from neuronal network instability and from a general state of hyperexcitability. This augmented excitability is also responsible for the epileptic phenotype that is often associated with paroxysmal dyskinesia. In this chapter, we summarize the current knowledge on the main genetic factors responsible for paroxysmal dyskinesia and the underlying physiopathological mechanisms that converge into the final common pathway of neuronal network hyperexcitability.