Familial paroxysmal ataxia (Orphanet_97, an Orphanet rare-disease nomenclature entry) can be described as follows. Episodic ataxia type 2 (EA2) is the most frequent form of Hereditary episodic ataxia (EA; see this term) characterized by paroxysmal episodes of ataxia lasting hours, with interictal nystagmus and mildly progressive ataxia. Also known as: Episodic ataxia type 2.