Introduction Complete occlusion of the internal carotid artery in a patient over 40 years of age often results in death or serious neurological deficit. The main features in the present case are the presence of the collateral circulation, which reduced the seriousness of complete occlusion, and the subsequent course, which included ipsilateral third nerve palsy, contralateral hemiparesis, peripheral visual field constriction, and facial pain resembling Sluder's sphenopalatine syndrome. Report of Case A 53-year-old white man was admitted to the hospital on May 22, 1957, with headache of one day's duration and transient numbness of the left arm and left side of the face. Family and past histories were noncontributory. Initial examination revealed a blood pressure of 140/80, weakness and a mildly hemiparetic gait on the left, arteriosclerotic changes in the ocular fundi, loss of response to pinprick on the left, and slightly hyperactive deep tendon reflexes on the right side.