Ｔｏｐｏｍａｐｐｉｎｇ Ｓｙｓｔｅｍによる眼球偏位の研究

Abstract

Eye deviation in the horizontal and vertical direction was studied with a topomapping system in normal subjects and patients with vestibular dysfunction in total darkness. The measurements were made under two conditions : (1) while looking straight ahead and (2) while moving the eyes up and down. Under the first con dition, the following results were obtained.1. In 20 normal subjects, horizontal eye position deviated 3 degrees or less and the vertical position 4 degrees or less, without showing any particular tendency to deviate from the median point.2. In normal subjects unilateral ice water irrigation caused the horizontal component to shift to the irrigated side in some subjects and to the contralateral side in others. The vertical component showed an upward deviation in most subjects, suggesting that this shift is caused by stimulation of the otolith organ.3. In 9 patients with vestibular neuronitis, all patients showed horizontal eye deviation to the affected side, vertical eye deviation was upwards in 6 patients and downwards in 3. All 3 patients with downward deviation had hypertension, cerebral arteriosclerosis and reduced brainstem blood flow on the affected side, and one of them had an abnormal ABR. These results suggest that downward eye deviation represents vestibular neuronitis complicated by brainstem impairment, as reported by Corvera, Wennmo and Pyykko.4. In patients with dead labyrinth, central compensation for eye deviation was examined with topomaps. The central nervous system's compensation was superior in the horizontal direction. It appears that 2 years are required for complete normalization of eye deviation. When the subjects moved their eyes up and down in total darkness, the following results were obtained.1. In 10 normal subjects, the width of the horizontal eye deviation was greater than that observed while they were looking straight ahead. The horizontal component of the center of gravity, however, was not differerent from the topomap when they were looking straight ahead. Large interindividual differences were observed in vertical eye movements.2. Topomapping was carried out in 7 patients who satisfied all of the following requirements : (1) equilibrium function tests revealed good vestibular compensation ; (2) the topomap with eyes looking straight ahead was normal or almost normal ; (3) unilateral vestibular dysfunction. In 5 subjects, the topomap was shifted to the affected side, and in 2 it was shifted to the healthy side.