Abstract

Differentiating peripheral from central pathology is most important in clinical practice of dizziness. The bedside examination for dizziness should include a systematic study of spontaneous and evoked nystagmus, head impulse test, evaluation of the ocular motilities including saccades, smooth pursuit, and optokinetic nystagmus. Examination of the balance and coordination function may disclose dysfunction of the cerebellar system. In contrast to the nystagmus of peripheral origin, the central nystagmus may show various patterns. Usually pure vertical and torsional nystagmus, direction-changing nystagmus, and nystagmus not suppressed by fixation indicates a central pathology. In case of positioning/ positional nystagmus which does not follow the characteristic patterns of benign paroxysmal positional vertigo and does not respond to repeated canalith repositioning maneuvers, a possibility of central positional vertigo should be considered. The patterns of head-shaking nystagmus (HSN) from central lesions include an unusually strong HSN elicited by weak head-shaking, initially ipsilesional HSN, strongly biphasic HSN, strong HSN in patients without caloric paresis, HSN in the opposite direction of spontaneous nystagmus and perverted HSN (e.g. downbeat nystagmus after horizontal head-shaking). Head impulse test is mostly negative in the central vestibulopathies, even in the presence of vertigo and spontaneous nystagmus. Disorders of ocular motility and coordination, and severe imbalance also suggest central lesions. Careful bedside evaluation provides valuable information on the underlying pathology of dizziness. Research in Vestibular Science 2009;8(2 suppl 1):S18-S21