Acquired Periodic Alternating Nystagmus

ABSTRACT

Periodic alternating nystagmus is a rare form of horizontal jerk nystagmus characterized by a periodical reversal in the direction of nystagmus. It implies a cerebellar disorder or lesions involving the vestibulocerebellar connections. We report a patient with an acquired form of periodic alternating nystagmus associated with meningoencephalitis. Its waveform characteristics were demonstrated by a video-nystagmogram. The brainstem lesions in our patient were thought to be responsible for her nystagmus.