椎骨脳底動脈系の血管病変に起因したと考えられた外転神経麻痺の4症例

Four Cases of Abducens Palsy Caused by a Vascular Lesion of the Vertebrobasilar System

I．はじめに

　外転神経麻痺の原因として血管障害・脳動脈瘤・外傷・腫瘍・糖尿病・髄膜炎など様々な疾患がある^7）が，椎骨脳底動脈系の血管病変が外転神経麻痺の原因となることは一般的には知られていない．一方で，解離性椎骨動脈瘤に，外転神経麻痺を高率に合併したとの報告がある^5）．そこでわれわれは外転神経麻痺を認めた症例の脳血管撮影所見，特に椎骨脳底動脈系に着目し，外転神経麻痺の原因について検討したので報告する．

Several pathological conditions are responsible for abducens palsy, but a lesion of the vertebral artery(VA) has rarely been recognized as one of the causes. It has been reported that a high percentage of casesof abducens palsy are involved with ruptured dissecting aneurysms of the VA. We investigate the verte-brobasilar anatomy in 4 patients, suffering with abducens palsy. One patient revealed a fusiform dilatationof the vertebral artery on the same side as the abducens palsy. Three patients were noted to have stenosisof the vertebral artery from the origin of the posterior inferior cerebellar artery (PICA) to the union. Final-ly, four patients were found to have abnormal vertebrobasilar anatomy, which was on the same side as theabducens palsy. It is conceivable that changes of vertebrobasilar circulation may cause abducens palsythrough direct compression, or ischemic events.