Geotropic central paroxysmal positional nystagmus in a patient with human immunodeficiency virus encephalopathy.

Central vestibular lesions may cause paroxysmal positional nystagmus (PPN) or paroxysmal positional vertigo as a result of lesions involving the brainstem dorsolateral to the fourth ventricle or the cerebellar nodulus/uvular region. PPN usually presents as persistent downbeating nystagmus during head hanging or as apogeotropic horizontal nystagmus during head turning in the supine position. Geotropic PPN during head turning in the supine position has not been previously reported. We report such a case in a patient with HIV encephalopathy.