Most common cause of SAH over age 20 years
Berry aneurysm rupture
Most common cause of SAH under age 20 years
Cause of saccular (berry) vs. fusiform aneurysm
Saccular - congenital deficiency in muscle coat at vessel junctions
Fusiform - diffuse atheromatous degeneration of arterial wall often a/w HTN
Risk of hemorrhage in patients who have first-degree relatives with aneurysmal SAH
7x increased risk = 2-5% lifetime risk
Risk of rebleeding following SAH? Mortality associated with rebleed?
50% risk of rebleeding
50% will die from rebleed
Timeline of vasospasm after SAH
Typically occurs within 2-3 days, rarely after 14 days
Surgical procedures available for tx of cerebral aneurysm
- Occlusion of neck of aneurysm
- Reinforcement of aneurysmal sac
- Proximal ligation of feeding vessel
What is the most frequent sign of an AVM? Second most common sign?
1. Hemorrhage (SAH or intracerebral)
Chance of hemorrhage from ruptured or unruptured AVM
3% per year
Sudden onset of severe HA should be regarded as what, until proven otherwise?
What is a 'sentinel' HA?
Small leak from an aneurysm resulting in minor HA
Presenting features of SAH
HA, diminished conscious state, meningism (neck stiffness, vomiting, photophobia, fever), focal neurologic signs, fundal changes (e.g. retinal hemorrhage)
What lobe does a middle cerebral artery aneurysm frequently rupture into? What symptoms would you expect?
Temporal lobe - hemiparesis and aphasia if dominant hemisphere is involved
What lobe does an anterior communicating artery aneurysm frequently rupture into? What symptoms would you expect?
Frontal lobes - akinetic mutism
What neurological signs would you expect from a posterior communicating artery aneurysm?
Pressure on CN3 causing ptosis, mydriasis, and extraocular muscle palsy
DDx of an apparently isolated CN3 palsy?
Posterior communicating artery aneurysm OR ischemic lesion from DM or atherosclerosis - if there is ANY doubt then obtain angiography
Why does a transient communicating hydrocephalus often occur after SAH?
Blood blocks the arachnoid villi
What are the 2 major classification systems for SAH?
Hunt and Hess - based on symptoms
WFNS (World Federation of Neurological Surgeons) - based on GCS score and motor deficits
Best initial investigation in suspected SAH? If there is any doubt, what do you obtain next?
CT; if any doubt then lumbar puncture looking for xanthochromia
What is the most common location for cerebral aneurysms?
Equal frequency at internal carotid (posterior communicating), anterior communicating, and middle cerebral arteries
How common are multiple aneurysms?
15% of cases have aneurysms at more than one position
Why are cerebral arteries more susceptible to weakening/degeneration?
Elastic layer of these arteries is limited to internal lamina
What hereditary syndromes are associated with cerebral aneurysm?
Marfans, Ehlers-Danlos syndrome, coarctation of aorta, polycystic kidney disease
How common is angiographic vasospasm following SAH?
50% of cases but only 25% result in serious neurological complications
Blood in the basal cisterns after SAH is correlated with what?
Risk of developing vasospasms; amount of blood is DIRECTLY correlated with risk and severity
Tx of vasospasm after SAH
No good tx; if aneurysm was surgically occluded then hypertensive therapy + hypervolemia; can consider CCB (e.g. nifedipine)
Vein of Galen malformation
Arteries feed directly into vein of Galen (drains into sinuses of posterior cerebral fossa); most frequent AVM in infants
How often is the cause of SAH unknown?
15% of cases
Identify the lesion
Diffuse SAH in bilateral Sylvian fissures and basal cisterns
Identify the lesion
Diffuse SAH (including basal cisterns)