Subarachnoid Hemorrhage

Question 1

What is the most common cause of SAH? What are other causes?

Answer 1

80% are from ruptured saccular aneurysms
Other causes: AV malformation, cavernous angioma, mycotic aneurysm, neoplasm, blood dyscrasia.
Can be secondary to an intraparenchymal hemorrhage that has dissected to include the subarachnoid space

Question 2

What is the age range for classic SAH?

Answer 2

40–60 years

Question 3

What is a mycotic aneurysm?

Answer 3

Bacterial infection of an arterial wall that leads to an aneurysm

Question 4

SAH accounts for what percentage of strokes?

Answer 4

10%

Question 5

Why is SAH so important to catch?

Answer 5

It is the most common cause of sudden death from a stroke

Question 6

If SAH occurs in kids or adolescents, what is the most likely cause?

Answer 6

Aneurysms are rare in kids, more likely AV malformation

Question 7

What are the risk factors for SAH?

Answer 7

Age, smoking, HTN, excess etoh use, use of sympathomimetic drugs

Question 8

What familial diseases are associated with SAH?

Answer 8

Polycystic kidney disease
Coarctation of the aorta
Marfan
Ehlers-Danlos type IV

Question 9

What is the average mortality rate for SAH?

Answer 9

32%

Many die before reaching the hospital

Question 10

What are the classic clinical features of SAH? (Signs and symptoms)

Answer 10

80% Thunderclap headache: worst in life (severe), peaks within seconds to minutes, can be associated with exertion including sex
50% Meningismus
20% Focal neuro findings
Others: syncope, nausea, vomiting, neck stiffness, photophobia, seizures
50% of those with a ruptured aneurysm are restless or altered consciousness
1/3 have a sentinel headache days to weeks before

Question 11

What scale is used to predict outcome in SAH based on symptoms? What are the primary symptoms?

Answer 11

Hunt and Hess clinical grading scale
Grade 1: no symptoms or minimal HA and slight nuchal rigidity
Grade 2: mod to severe HA, nuchal rigidity, no neuro deficit other than CN palsy
Grade 3: drowsy, confused, mild focal deficit
Grade 4: stupor, mod to severe hemiparesis
Grade 5: deep coma, decerebrate posturing, moribund appearance

Question 12

Disorders that can mimic the headache of SAH

Answer 12

Cervical artery dissection
Cerebral venous thrombosis
Reversible cerebral vasoconstriction syndrome
Stroke
Migraines and cluster HA's

Question 13

Timing of head CT and reliability of results for SAH

Answer 13

Within 6 hours, considered 100% Sens and Sp.
Within 24 hours, considered greater than 90% sensitive
Drops to less than 50% at one week

Question 14

Workup to confirm SAH

Answer 14

Non-contrast head CT

If negative and still suspect, then an LP is recommended

Question 15

How to differentiate between SAH and traumatic LP

Answer 15

CSF should be spun down with the supernatant observed for xanthochromia which is a product of the breakdown of hemoglobin with yellow pigments that remain. This may take 12 hours to occur.
RBC less than 100 in tube 4 makes SAH unlikely