Subarachnoid hemorrhages:
Pathophysiology:
-Mean age 40-60, but can happen at any age; 1.6x more frequent in women than men.
-Etiologies: Main are sacular aneurysm rupture and trauma. Less common are perimesencephalic nonaneurysmal
subarachnoid hemorrhage (usually benign bleed), vascular malformations, intracranial dissections, amyloid angiopathy.
-Incidental aneurysms: Very common; most don’t bleed. If <6mm, refer to neurosurgery and monitor with yearly CTA.
Consider surgery if 7mm or greater.
-Most aneurysm ruptures only bleed for seconds (though under arterial pressure).
-Typical locations for aneurysms: ACA (40%), MCA bifurcation (34%), PCOMM (20%), basilar tip (4%).
-SAH risk factors: Smoking, HTN, heavy alcohol use, cocaine, Polycystic Kidney Disease, Ehler’s-Danlos Syndrome, family
hx of SAH.
Symptoms:
-Thunderclap “worst headache of life” (80%) , LOC (5%) , n/v (75%), nuchal rigidity (35%), seizures (20%).
-Can have mild headache from “sentinel bleed” a few days to weeks prior to aneurysm rupture.
Diagnosis:
STEP 1: Initially, NCHCT (sensitivity 98% at 12 hours, 93% at 24 hours, 57-85% at 6 days). If CT head neg, get LP.
STEP 2: Vessel angiography (conventional angio is gold standard and can do procedures based on results; CTA> MRA as
less ideal alternative).
-? MRA: sensitivity for detecting aneurysm >5mm is 85-100%; for aneurism <5mm is 56%.
-? CTA: sensitivity for detecting aneurysm >is 95-100%; for aneurism <5mm is 64-83%. In 74% of cases, angiography
after CTA did not provide any new information.
Management:
A) If ruptured aneurysm, and it is NOT YET SECURED:
-Avoid overstimulation, aggressive pain control, intubation if GCS <=8, reverse anticoagulation until aneurysm is secure,
control BP with systolic goal <140, using nicardipine gtt (avoid nitro gtt due to increased ICP).
-Perform coiling or clipping EARLY. The decision of which one to use is very situation-specific. In GENERAL, use clipping if
MCA or PCOMM, coiling if posterior circulation otherwise; unclear if ACA.
B) If ruptured aneurysm and it HAS BEEN SECURED, OR is non-aneurysmal SAH: Focus on medical management
-Nimodipine 60mg q4H x 21 days to prevent vasospasm/delayed cerebral ischemia/DCI (30-70% of cases; greatest
narrowing at days 4-14 after bleed); avoid hyperventilation
-Triple H therapy (hypertension, hypervolemia, hemodynamic stability)
-Permissive hypertension (causes profound reductions in cerebral blood flow, reduced cerebral autoregulation, and
acute ischemia)
-Bedrest
-Maintain euvolemia
-Tobacco cessation consult/modify risk factors
-Maintain hemoglobin > 8-10
- Antiepileptic prophylaxis PROBABLY NOT WARRANTED
- Start SQH prophy 24 hours after surgery; start SCDs immediately.
Monitor for:
1) Delayed cerebral ischemia (DCI)/vasospasm: Get daily TCDs to monitor (Lindegaard ratio of 5-6 strongly suggests
severe vasospasm; if concern, get repeat angiogram). If present, take to angio lab and do balloon angioplasty for
treatment of focal vasospasm, and intra-arterial vasodilators (ie, nicardipine) for treatment of diffuse vasospasm.
2) Rebleeding (mortality 70% if present; max risk of 4% is in first 24 hours, increasing by 1% per day for 30 days, then by
3% every year) this is why you want to secure aneurysm fast.
3) Increased ICP: If concerned, put ICP monitor. Consider ventriculostomy if evidence of hydrocephalus on CT, or WFNS
>= 3. May do hemicraniectomy if refractory to medical management with drainage/hypertonic saline/mannitol.
=Obstructive hydrocephalus: 15% of patients. Classically present with decreased level of consciousness, enlarged
ventricles on CT, and downward-going eyes. Major risks are intraventricular extension of hemorrhage, and posterior
circulation aneurysms. Treat with ventriculostomy for drainage. 1/3 will develop shunt-dependant chronic
hydrocephalus.
=Seizures: 0.2% have GTCs, 7% have subclinical seizures. Can be MAJOR concern if aneurysm is not secured yet due to BP
rise during seizure. Usually, no prophylaxis is warranted, but treat with AEDs if clinical seizures noted.
=Cardiac abnormalities (ie, fatal arrhythmias or stunned myocardium; 40% have EKG changes, namely ST depressions,
QTc prolongation, transient diffuse T wave inversions) 2/2 sympathetic surge
=Pulmonary abnormalities (pulmonary edema) 2/2 sympathetic surge.
= Hyponatremia from SIADH (from hypothalamic damage, euvolemic) vs. cerebral salt wasting (from excess BNP causing
salt loss and fluid loss, hypovolemic), treat with isotonic saline +/- salt tabs. In certain circumstances, consider
hypertonic saline.
Prognosis:
-10% die before getting to hospital, 25% die in first 24 hours, and 50% dead within 30 days; only 1/3 have good
outcome.
-Predictors of poor outcome in acute setting: Level of consciousness/neurologic status, size of bleed, patient age.
-Risk of NEW aneurysm formation after ruptured aneurysm is 1-2% per year.
-prognostication: Not many good tools.
HUNT-HESS SCALE FOR RUPTURED ANEURYSMS:
WFNS SCORE FOR RUPTURED ANEURYSMS:
Fischer Grade (for risk of vasospasm):
(Risk of vasospasm 20%, 25%, 37%, and 31%, respectively)
Hyponatremia treatment:
For Na level <133 mEq/L or a decrease of 6 mEq/L in 24 to 48 hours:
1. NaCl tabs 3 g PO/NGT every 6 h
2. Initiate 3 percent NaCl infusion at 20 mL/h IV
3. Check serum Na every 6 hours
a. If Na <130 mEq/L:
Increase rate by 20 mL/h (max rate = 80 mL/h)
If on hold at present, initiate 3 percent NaCl infusion at 20 mL/h IV
b. If Na = 130 to 135 mEq/L:
Increase rate by 10 mL/h (max rate = 80 mL/h)
If on hold at present, initiate 3 percent NaCl infusion at 10 mL/h IV
c. If Na = 136 to 140 mEq/L:
No change
d. If Na ≥140 mEq/L:
Hold infusion
REFERENCES:
-Guidelines for Management of aneurysmal Subarrachnoid hemorrhage: A statement for health care professions from a
special writing group of the stroke council, American Heart Association (Stroke, 2009)
-Critical Care Management of Patients following aneurysmal subarachnoid hemorrhage; recommendations from the
neurocritical care society’s multidisciplinary consensus conference. (Neurocritical care, 2011)
Up-to-Date (duh)