 Also known as periodic vestibulocerebellar ataxia, type-4 episodic ataxia (EA4) is an extremely rare form of episodic ataxia differentiated from other forms by onset in the third to sixth generation of life, defective smooth pursuit and gaze-evoked nystagmus.Patients also present with vertigo and ataxia.There are only two known families with EA4, both located in North Carolina.