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 GLUT1, deficiency).
There are other clinical pictures that do not exactly constitute movement disorders, but 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.