The dizzy patient: don't forget disorders of the central vestibular system.

Vertigo and dizziness are among the most common complaints in neurology clinics, and they account for about 13% of the patients entering emergency units. In this Review, we focus on central vestibular disorders, which are mostly attributable to acute unilateral lesions of the bilateral vestibular circuitry in the brain. In a tertiary interdisciplinary outpatient dizziness unit, central vestibular disorders, including vestibular migraine, comprise about 25% of the established diagnoses. The signs and symptoms of these disorders can mimic those of peripheral vestibular disorders with sustained rotational vertigo. Bedside examinations, such as the head impulse test and ocular motor testing to determine spontaneous and gaze-evoked nystagmus or skew deviation, reliably differentiate central from peripheral syndromes. We also consider disorders of 'higher vestibular functions', which involve more than one sensory modality as well as cognitive domains (for example, orientation, spatial memory and navigation). These disorders include hemispatial neglect, the room tilt illusion, pusher syndrome, and impairment of spatial memory and navigation associated with hippocampal atrophy in cases of peripheral bilateral vestibular loss.