Chronic Dizziness of Central Origin

Abstract

Vestibulo-ocular reflex (VOR), one of brainstem reflexes that maintains balance, is controlled by the cerebellum. This cerebellar control system of VOR is further coordinated by the cerebrum (e.g., visual suppression of VOR). Therefore, in central lesions, dysregulated, abnormally increased VOR gain may be the underlying pathology of chronic dizziness, unlike in peripheral vestibulopathy, which always involves decreased VOR gain. The characteristics of VOR dysregulation are quite different between brainstem-cerebellar lesions and cerebral lesions. Abnormally increased VOR gain is the major mechanism underlying the chronic dizziness in patients with brainstem-cerebellar lesions, whereas decreased visual suppression rate of VOR is the major mechanism underlying the chronic dizziness in patients with cerebral lesions. Of course, there could be coexisting peripheral vestibulopathy (decreased VOR gain), so that it is necessary to consider all pathologies causing increased VOR gain, decreased visual suppression rate of VOR, and decreased VOR gain to identify the precise mechanism of dizziness, especially in eldery people.