[Agenesis of left internal carotid artery associated with megadolichobasilar anomaly and olivopontocerebellar atrophy].

A case of agenesis of the left internal carotid artery associated with megadolichobasilar anomaly (MDBA) and olivopontocerebellar atrophy (OPCA) was reported. A 73-year-old female had a three-year history of slowly progressing gait disturbance. On admission neurological examination revealed bilateral cerebellar ataxia and dysarthria with increased muscle stretch reflexes and extensor planter response in the left. CT and MRI showed marked atrophy of the brain stem and cerebellum with brain stem rotation and deviation to the right. Total absence of the left internal carotid artery was demonstrated angiographically. The left anterior and middle cerebral arteries were fed by the tortuous megadolichobasilar artery through the enlarged posterior communicating artery. The left ophthalmic artery was fed by the left middle meningeal artery. By the high resolution CT at the skull base, the lack of the carotid canal was demonstrated on the left side. The interesting clinical features of a case of agenesis of the left internal carotid artery were discussed. This case showed a clinical and radiological signs and symptoms of OPCA though any influences by MDBA could not be excluded.