In this condition, the person has a sensation of turning or rotation in space in the absence of actual rotation. Usually, debris from the otolithic membrane, located in the saccule and utricle, accumulates at the ampulla of the posterior semicircular canal and adheres to the cupula, making it more sensitive to angular movement. Vertigo is often accompanied by nausea, vomiting, and gait ataxia. It can be caused by peripheral vestibular lesions that affect the labyrinth of the inner ear or the vestibular division of CN VIII. It can also be caused by central lesions that affect the brainstem vestibular nuclei or their connections. Vertigo due to peripheral lesions is usually intermittent, lasts for brief periods of time, and is always accompanied by unidirectional, but not vertical, nystagmus. Vertigo due to central lesions may or may not be accompanied by nystagmus. If nystagmus is present, it may be vertical, unidirectional, or multidirectional. Some HI receptor antagonists (., the piperazine derivatives, cyclizine, and meclizine) and promethazine (a phenothiazine) have proved to be beneficial in the treatment of vertigo. Promethazine has the added advantage of relieving vomiting, which commonly accompanies vertigo.