Vestibulo-oculomotor characteristics in surgically treated patients with cerebellar haemangioblastoma (Lindau tumor).

In a survey of 18 patients that were operated on because of a cerebellar haemangioblastoma (Lindau tumor) 94% showed characteristic cerebellar oculomotor deficits when DC EOG recordings were analyzed. Only 22.1% showed also clinically cerebellar deficits. We studied the vestibular ocular reflex (VOR) with and without visual interaction, and also saccades and pursuit eye movements in our patients with lesions involving one cerebellar hemisphere (n = 14) or the vestibulocerebellum (n = 4). Gain of dysmetric saccades ipsilateral to the side of the lesion was significantly increased; gain of pursuit eye movements, that were often saccadic, was decreased contralaterally. Our patients showed highly increased responses for all three conditions of visual-VOR-interaction (sinusoidal or steplike rotation in the dark, in the light with fixed surround, or in the dark with head fixed fixation point) ipsilateral to the lesion, together with a remarkable inability to modulate their VOR with vision on this side. With movements contralateral to the side of the lesion they showed a larger variability of test responses than normals, but only for fixation suppression of the VOR a significantly increased gain. The very similar time constants of slow phase decay after a step change in chair velocity indicated a similar poor modulation of visual-VOR-interaction under these 3 conditions for stimulations ipsilateral to the lesion. Contrariwise, optokinetic step stimulation demonstrated a generally impaired response that was significantly lowered towards the side contralateral to the lesion. Our results indicate the critical function of the cerebellum for voluntary fast and slow eye movements as well as for visual-vestibular interaction in humans.