Diagnostic criteria for central versus peripheral positioning nystagmus and vertigo: a review.

Head positioning can lead to pathological nystagmus and vertigo. In most instances the cause is a peripheral vestibular disorder, as in benign paroxysmal positioning vertigo (BPPV). Central lesions can lead to positional nystagmus (central PN) or to paroxysmal positioning nystagmus and vertigo (central PPV). Lesions in central PPV are often found dorsolateral to the fourth ventricle or in the dorsal vermis. This localization, together with other clinical features (associated cerebellar and oculomotor signs), generally allows one to easily distinguish central PPV from BPPV. However, in individual cases this may prove difficult, since the two syndromes share many features. Even if only BPPV as a peripheral lesion is considered, differentiation based on such features as latency, course, and duration of nystagmus during an attack, fatigability, vertigo, vomiting, and time period during which nystagmus bouts occur, may be impossible. Only the direction of nystagmus during an attack can allow differentiation.