A New Neurotological Test Using Vision Reversal Prisms

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  • 左右逆転視プリズムを用いた新しい神経耳科学検査法
  • サユウ ギャクテン シ プリズム オ モチイタ アタラシイ シンケイ ジカガク

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Abstract

The adaptation of the vestibulo-ocular reflex (VOR) was studied in 26 patients with cerebellar lesions, using horizontal vision-reversal prisms. In normal subjects, the adaptation of gain after wearing prisms for one hour was approximately 50% of the VOR value in the dark. In contrast to this, patients with cerebellar lesions showed less adaptation, approximately 20% after a one-hour forced adaptation task. From the analysis of the data, three different types of abnormalities were classified. These were: type A, higher gain in the initial level and abnormal adaptation; type B, higher gain in the initial level and normal adaptation; and type C, normal initial level and abnormal adaptation. Patients showing typical type A responses tended to have severe widespread or midline lesions of the cerebellum. Typical type B patients had mild cerebellar lesions, and typical type C patients tended to have lesions restricted to one side of the cerebellum. From these results, it can be speculated that the reduction of VOR adaptation occurs when one side of the cerebellum has severe lesions but that if at least the remaining half of the cerebellum is intact, it is sufficient to produce a normal vestibulo-ocular reflex.

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