Central and peripheral vertigo can be differentiated based on the type of nystagmus or abnormal eye movements. For example, in peripheral vertigo, the nystagmus lessens or disappears when the patient focuses the gaze. It does not lessen in central vertigo and persists for a longer time. Symptoms in central vertigo usually last for a longer duration. Peripheral vertigo usually has a more sudden onset than central vertigo; an exception to this is a stroke, which is a central cause of vertigo of sudden onset.