[Dizziness/vertigo caused by small cerebellar/brainstem strokes].

Unlike brainstem strokes, small cerebellar strokes can cause isolated dizziness/vertigo with horizontal nystagmus mimicking vestibular neuritis or direction-changing apogeotropic positional nystagmus mimicking benign paroxysmal positional vertigo. Horizontal nystagmus caused by cerebellar strokes were directed toward the side of the lesion, and enhanced when the patient lie on the non-affected side; the enhanced nystagmus were apogeotropic at this position. Direction-changing apogeotropic positional nystagmus, caused by similar cerebellar lesions, were also enhanced when the patient lie on the non-affected side. A possible mechanism of this enhancement of the two nystagmus may be a disinhibition of the otolich-ocular responses.