Amnesia after operations on aneurysms of the anterior communicating artery.

All patients with ruptured aneurysms admitted to neurosurgical departments in Denmark after April, 1978, are the subjects in the prospective study that includes neuropsychological examinations. Data from 48 patients with aneurysms of the anterior communicating artery have been analyzed. Trapping of the aneurysm was done in 11 patients and resulted in an amnesic syndrome in 9. Thirty-seven patients were operated upon by ligation of the neck of the aneurysm or similar procedures, resulting in 6 cases of amnesia. Trapping invariably disrupts blood supply through newly described dorsal perforating branches from the anterior communicating artery. These perforating branches may supply areas of vital importance to memory function.