Differentiating between peripheral and central causes of vertigo.

The history usually provides the key information for distinguishing between peripheral and central causes of vertigo. Probably the only central lesion that could masquerade as a peripheral vestibular lesion is cerebellar infarction because vertigo and severe imbalance may be the only presenting features. MRI is indicated in any patient with acute vertigo and profound imbalance suspected to be the result of cerebellar infarct or hemorrhage. Patients with chronic recurrent attacks of vertigo often have normal examination results, including normal vestibular function in between attacks. The duration of attacks is most helpful in distinguishing between central and peripheral causes; vertigo associated with vertebrobasilar insufficiency typically lasts minutes, whereas peripheral inner ear causes of recurrent vertigo typically last hours. Positional vertigo nearly always is a benign condition that can be cured easily at the bedside, but in rare cases it can be a symptom of a central lesion, particularly one near the fourth ventricle. Central positional nystagmus is nearly always purely vertical (either upbeating or downbeating), and there are usually associated neurologic findings.