歯状核変性症と眼球運動障害

Oculomotor disturbances of the degenerative disease of the dentate nucleus.

I．はじめに

　小脳歯状核変性を主な特徴とする疾患として，Joseph病と歯状核・赤核・淡蒼球・ルイ体萎縮症（dentato-rubro-pallido-Luysian atrophy：DRPLA）が知られている。Joseph病は常染色体優性遺伝を示す。臨床的には小脳失調，錐体路徴候，眼球運動障害，ジストニアや固縮，筋萎縮，知覚障害などを特徴とし，病理学的には小脳歯状核，橋核，黒質，前角細胞，クラーク柱の神経細胞，脊髄小脳路，動眼神経・前庭神経などの脳神経核の変性や神経細胞の脱落を示す。一方，DRPLAは家族発症の濃厚なものと孤発例とがある。臨床的には（1）運動失調，舞踏病・アテトーゼなどの不随意運動，痴呆，眼球運動障害を示すataxo-choreoathetoid型，（2）舞踏病と知能障害，精神症状を呈するpseudo-Huntington型，（3）ミオクローヌス，てんかん，痴呆を呈するmyoclonic epilepsy型に分けられている^8）。病理学的にはいずれも歯状核，上小脳脚，赤核，淡蒼球外節，ルイ体の変性や細胞脱落を特微としている。ataxo-choreoathetoid型では眼球運動障害が強く，病理学的にも脳幹被蓋部の萎縮が認められ，責任病巣と考えられている。

　Oculomotor disturbances of the patients with Joseph's disease and dentato-rubro-pallido-Luysian atrophy (DRPLA) were studied and compared with those of the patients in literature. The subjects with Joseph's disease consisted of our 12 patients who belong to the same family and 86 patients in literature. The subjects with DRPLA consisted of our 10 patients and 43 patients in literature.

　Oculomotor characteristics of Joseph's disease included: 1) limitation of upward gaze and horizontal gaze nystagmus were present frequently and from the early stage of illness, 2) pupillary light reflex was normal in spite of upward gaze paralysis and convergence deficit, 3) pursuit and saccadic eye movements were also frequently disturbed as well as optokinetic nystagmus, caloric response and visual suppression of caloric nystagmus, 4) difficulty of eyelid opening, bulging eyes and involuntary eye movements such as square wave jerks and opsoclonus were present.