Paroxysmal movement disorders are a heterogeneous group of diseases with recurring episodes of symptoms related to involuntary movements characterized by a sudden onset and a more or less abrupt disappearance after a variable period.
Strictly speaking, this definition includes several known forms of episodic dyskinesia, classified below according to their triggering factor:
- Paroxysmal kinesigenic dyskinesia (particularly associated with pathogenic variants in the PRRT2 gene)
- Paroxysmal non-kinesigenic dyskinesia (particularly associated with pathogenic variants in PNKD and KCNMA1)
- Exercise-induced dyskinesia (particularly associated with pathogenic variants in the SLC2A1 gene, also known as glucose transporter deficiency or GLUT-1 deficiency)
There are other clinical pictures that do not exactly constitute movement disorders, but they share the common characteristic of paroxysmal neurological symptoms with a fairly similar pathophysiological basis (many of them are channel-mediated) that, on occasion, can overlap to some degree in common clinical practice.