小脳片葉と前庭動眼反射

概要

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Vestibulo-oculomotor functions were studied before and after the flocculus in rhesus monkeys was extirpated under the operating microscope by a sub-occipital approach in 28 cases. Eye movements and eye speed were recorded by needle electrodes on electronystagmography. In 10 cases, the flocculus were stereotaxically extirpated. In all cases, neither spontaneous nor positional nystagmus were markedly provoked. Optokinetic nystagmus (OKN) was not makedly changed in the cases with unilateral lesion. The slow phase velocity of OKN increased up to 50/sec even in the cases with bilateral lesion. Caloric response in the cases with unilateral lesion initially showed mild DP to the ipsilateral side. The duration and the maximum slow phase velocity of caloric nystagmus were within normal limits in the cases with bilateral lesion. Visual suppression of nystagmus at maximum amplitude was studied in the animals which were exposed to light for 10 sec in darkness during the maximum caloric test. Visual suppression of nystagmus in normal animals was about 50 %. Visual suppression of nystagmus to the ipsilateral side was reduced or lost in the cases with unilateral lesions and visual suppression to both sides were reduced or lost in the cases with bilateral lesions. The flocculus appeared to be essential for maintaining the visual suppression of vestibular nystagmus.
社団法人日本耳鼻咽喉科学会の論文