Basal encephalocele associated with hypoplasia of the internal carotid artery.

A 22-year-old woman presented with a basal encephalocele associated with hypoplasia of the internal carotid artery (ICA) manifesting as a 6-year history of decreased vision in the right eye. She underwent encephalo-arterio-synangiosis under a diagnosis of hypoplasia of the ICA at age 6 years. Magnetic resonance imaging showed the encephalocele medial to the right temporal lobe. Frontotemporal craniotomy was performed for resection of the encephalocele and repair of the defect of the skull base. The pathogeneses of these developmental anomalies were probably related to developmental failure of the embryonic primordium during the 4th and 10th weeks.