Aperiodic alternating nystagmus: report of two cases and treatment by baclofen.

We report two cases of non periodic alternating nystagmus, one of vascular origin (ischemia of the vertebrobasilar territory) and a second of traumatic origin (whiplash injury) with otoneurological signs, typical of lesions in posterior cranial fossa and in particular of vestibulum-cerebellum and brainstem: gaze paretic nystagmus, rebound nystagmus, saccadic dysmetria, vestibular hyperreflexia and impaired visual suppression test. In one case it was possible to give baclofen therapy, which yielded positive results. Suspension of drug administration resulted in the worsening of clinical signs. The mechanism of action of the drug will be discussed.