中脳小梗塞に伴う動眼神経不全麻痺が生じた糖尿病患者の1例

Midbrain infarction with oculomotor paresis in a diabetic patient

　糖尿病歴11年，高血圧歴2年の61歳女性に右眼瞼下垂が1週前に生じた。右眼に上転と内転障害があった。瞳孔反応は正常であった。頭部CT検査で異常がなく，虚血性の動眼神経麻痺が疑われた。MRI検査で中脳腹側に小病変が発見され，この部の右動眼神経線維束障害が動眼神経不全麻痺の原因であると推定された。下斜筋，上直筋，上眼瞼挙筋，内直筋に障害があり，下直筋と瞳孔が障害されていなかったことは，中脳の動眼神経線維東内でこれら障害筋の線維配列が近接しているとする従来の解剖学的知見に合致する所見であった。

A 61-year-old female presented with right blepharoptosis of one week's duration. She had had diabetes for 11 years and systemic hypertension for 2 years. She showed limited upgaze and abduction in the right eye. Pupillary reflexes were normal. Computed tomography showed normal findings. She was tentatively diagnosed as oculomotor paresis of ischemic origin. Magnetic resonance imaging (MRI) showed a small lesion in the ventral midbrain, suggesting impaired oculomotor nerve fascicles in this area as the cause of oculomotor paresis. The findings also suggest the proximity of nerve fibers for the affected extraocular muscles and are in agreement with the reported anatomical arrangement of fascicular fibers in the midbrain.