両側眼瞼下垂と両側眼球上転障害を呈し，瞳孔正常であった中脳出血の1例

Bilateral Ptosis and Upper Gaze Palsy with Pupil Sparing Caused by Midbrain Hemorrhage

要旨　症例は65歳女性。突発性の開眼困難を主訴に受診し，精査加療目的入院となった。神経学的には，両側眼瞼下垂，両側上転障害を認め，瞳孔径，対光反射・輻輳反射は正常であった。そのほか脳神経，運動，感覚障害を認めなかった。

　MRIにて中脳被蓋背側を中心とした出血と診断した。保存的療法施行にて，眼瞼下垂・眼球上転障害は改善した。瞳孔正常で外眼筋麻痺を呈した中脳出血の稀な症例を通して，ヒトにおける中脳動眼神経核の配列および上直筋の交叉性支配について考察したので報告した。

The arrangement within the midbrain oculomotor nerve complex and crossed innervation of the superior rectus muscle are not elucidated in humans. A 65-year-old woman visited our hospital complaining of difficulty opening her eyes. Neurological examination revealed bilateral ptosis and impaired supraduction. The pupils prompty constricted to light. Results of CT and MRI demonstrated that there was a hematoma located in the dorsal midbrain tegmentum that spared the rostral midbrain. It was presumed that the nerves of the superior rectus and levator palpebrae lie in the midbrain tegmentum more dorsally and medially than the others. Furthermore, crossed innervation of the superior rectus muscle can explain that lesions located in the dorsal midbrain tegmentum cause more often impaired supraduction.

（Received : May 9, 2005）