Unusual aneurysms of the distal internal carotid artery.
BACKGROUND
Supraclinoid carotid aneurysms have traditionally been classified according to their relation to the major carotid branches, but considerable variation exists with respect to site of origin, projection, and relationship to the skull base. Distal internal carotid aneurysms with a superior or medial projection are uncommon vascular lesions, with an unusually high incidence of operative complications.


METHODS
Surgical experience with five patients suffering from subarachnoid hemorrhage due to ruptured aneurysms of the dorsomedial wall of the distal internal carotid artery is presented, with emphasis on their angiographic appearance, anatomical features, and operative management.


RESULTS
All five patients underwent surgical clipping. Intra-operative rupture occurred in two cases, with avulsion of the aneurysm from the internal carotid artery in both. A third patient experienced recurrent subarachnoid hemorrhage three days after uneventful surgery, due to the clip shearing off of the parent vessel.


CONCLUSIONS
Distal internal carotid aneurysms do not conform to the usual principles of aneurysm formation and are unique in their dorsomedial location unrelated to an arterial bifurcation. Although their anatomy is straightforward and exposure is not restricted by bone or dural structures of the skull base, they possess extremely fragile necks which make surgical management particularly hazardous.
Department of Surgery, University of British Columbia, Vancouver.
G J
GJ
Redekop
B
B
Woodhurst
D017542:Aneurysm, Ruptured / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D013345:Subarachnoid Hemorrhage / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D014057:Tomography, X-Ray Computed