先天性眼運動失行例の内耳温度刺激検査所見

Caloric Response in a Case of Congenital Ocular Motor Apraxia

　I．はじめに

　内耳の温度刺激では律動的な衝動性眼振が発現し，その緩徐相は末梢器管である半規管のクプラの偏位により前庭―眼反射（VOR）が起こり，眼球が一方向へ偏位する。この偏位が中枢神経系で察知されると眼球偏位を是正するように正中位へ戻され急速相が発現する。この反射がクプラの偏位が続く限り繰り返され，律動的な衝動性眼振がみられる。さて，この急速相発現に関与する中枢系に関しては最近明らかにされつつある。今回，VORは保たれているが急速相発現に障害がみられた例を経験したので，その障害部位について考察し，さらに回転，温度，視刺激によって起こる眼振第2相についても少しく述べてみたい。

　In a case of hereditary cerebellar ataxia with congenital ocular motor apraxia, the cold caloric stimulation did not induce the jerking type nystagmus but only the deviation of the eyes to the side of irrigation. This deviation of the eyes is the vestibulo-ocular reflex which implies the slow phase lacking the fast phase of caloric nystagmus. According to this caloric response, the fast phase of vestibular nystagmus originates in the central nervous system which is supposed the parapontine reticular formation.

　After the caloric deviation of the eyes returned to the center, the eyes deviated again slightly to the opposite side of irrigation. This second deviation was supposed the secondary phase of caloric response, which is conceivable to originate in a part of the vestibulo-ocular reflex. We supposed that the occurence of secondary phase of caloric nystagmus was due to the interplay in the nuclei of eye movement which is common to the secondary phase of optokinetic nystagmus.