Subarachnoid hemorrhage

1. Where are the majority of saccular (berry) aneurysms found?
2. What size aneurysms are most likely to rupture?
3. What is the peak age for rupture?
4. What are the symptoms due to aneurysm?
5. What are the symptoms of rupture?
6. What is the most common complications and how are they treated?

Answers:
1. 90-95% occur on the anterior circle of Willis.
2. If 10mm or larger, usually while active.
3. fifth and sixth decades.
4. Usually asymptomatic, may have compression of CN 3 (with posterior aneurysm).
5. Sentinel HA (50% of patients), LOC, CN 3 or 6 palsy, hemiparesis, aphasia, memory loss, seizures.
6. Risk of early rebleeding is 50-60%. Vasospasm occurs in 25%, caused by vasoactive blood breakdown products, 3-12 days after rupture. It is treated with nimodipine.