Anterior Communicating Artery Aneurysm
Findings:
Axial noncontrast head CT shows hyperdense material in
the basal cisterns and sylvian fissures, consistent with subarachnoid hemorrhage.
AP right common carotid arteriogram shows a rounded contrast collection
in the region of the anterior communicating artery, consistent with aneurysm.
Discussion:
80-90% of nontraumatic SAH is due to aneurysm. ACOM aneurysms
are among the most common, representing approximately 1/3 of intracranial
aneurysms. Large ACOM aneurysms may present with an optic chiasmal syndrome
(bitemporal hemianopsia). 15-20% of pts will have multiple aneurysms. Although
any size aneurysm may rupture, those measuring greater than 3-5 mm are
at higher risk. Complications include communicating hydrocephalus, rebleeding
(20%), vasospasm (>7d) +/- infarct. 1/3 of pts die immediately, 1/3 have
long term deficit, and 1/3 have normal outcome. For further discussion
of aneurysms, please refer to unknown cases 77, 86, 88, 93, 96, 101, 105,
116, 126, 134, and 150.