Episodic ataxia (EA) is an autosomal dominant neurologic condition affecting less than 1 in 100,000 people. It is characterized by spells of incoordination and imbalance (ataxia) with or without myokymia. Type 2 episodic ataxia (EA2) is characterized by acetazolamide-responsive attacks of ataxia with or without migraine. Patients with EA2 may also present with progressive cerebellar atrophy, nystagmus, vertigo, visual disturbances and dysarthria. These symptoms last from hours to days, in contrast with EA1, which lasts from seconds to minutes. Like EA1, attacks can be precipitated by emotional or physical stress, but also by coffee and alcohol. EA2 is also referred to as episodic ataxia with nystagmus, hereditary paroxysmal cerebellopathy, familial paroxysmal ataxia and acetazolamide-responsive hereditary paroxysmal cerebellar ataxia (AHPCA).