Subarachnoid hemorrhage

Epidemiology

Risk Factors (in order of relative risk)

Sudden, severe headache (97% of cases)
Sudden onset is more important finding than worst HA
May be associated with syncope, seizure, nausea/vomiting, and meningismus
Meningismus may not develop until several hours after bleed (caused by blood breakdown > aseptic meningitis)
Retinal hemorrhages
May be the only clue in comatose patients
Approximately 30-50% will have sentinel bleed/HA 6-20 days before SAH

Non-Contrast Head CT
92% specific if performed w/in 24 hours of bleed
~100% sensitive if performed w/in 12 hours of bleed
91% sensitive in patients w/ normal neuro exam
Decreases to ~50% sensitive by day 5
Not as sensitive/specific for minor bleeds
SAH 2/2 aneurysm (90%) - look in cisterns (especially suprasellar cistern)
SAH 2/2 trauma - Look at convexities of frontal & temporal cortices
Lumbar Puncture
Mandatory if there is a strong suspicion of SAH despite a normal head CT
Findings:
Elevated RBC count that doesn't decrease from tube one to four
(Decreasing RBCs in later tubes can occur in SAH; only reliable if RBC count in final tube is nl)
Opening pressure > 20 in 60% of patients with SAH
Can help differentiate from a traumatic tap (opening pressure expected to be normal)
Elevated opening pressure also seen in cerebral venous thrombosis, IIH
Xanthrochromia
May help differentiate between SAH and a traumatic tap
Takes at least 2 hours after the bleed to develop (beware of false negatives)
Sensitivity (93%) / specificity (95%) highest after 12 hours
If unable to obtain CSF consider CTA

Nimodipine
Associated with improved neuro outcomes and decreased cerebral infarction
Must be given 60mg q4hr PO or NGT only! (never IV)
BP control
No consensus on HTN (incr BP may maintain CPP but may also increase rate of bleeding)
If pt is alert this means CPP is adequate so can try lowering sbp to < 140
If pt is ALOC consider leaving BP alone, as the ALOC may be 2/2 reduced CPP
If BP control is necessary, LABETALOL, ESMOLOL or NICARDIPINE is preferred
Avoid vasodilators such as nitroprusside or NTG (increase cerebral blood volume --> increased ICP)
Discontinue/reverse all anticoagulation!
Seizure prophylaxis
Controversial; some evidence suggests anti-epileptic drugs may worsen outcomes; 3 day course may be preferable
Glucocorticoid therapy
Controversial; available evidence suggests is neither beneficial nor harmful
Glycemic control
Controversial; consider sliding scale if long pt stay in ED while awaiting ICU bed
Avoid hypovolemia

Rebleeding
Risk is highest within first 24 hours (2.5-4%), particularly within first 6 hours
Usually diagnosed by CT after acute deterioration in neuro status
Only aneurysm treatment is effective in preventing rebleeding
Vasospasm
Leading cause of death and disability after rupture
Typically begins no earlier than day three after hemorrhage
Characterized by decline in neuro status
Aggressive treatment can only be initiated after the aneurysm has been treated (sx or intraluminal tx)
Triple-H therapy (hemodilution + induced hypertension (pressors) + hypervolemia)
Cardiac abnormalities (?2/2 release of catecholamines due to hypoperfusion of hypothalamus)
Ischemia
Elevated troponin (20-40% of cases)
ST segment depression
Rhythm disturbances
Torsades, a fib, a flutter
QT prolongation
Deep, symmetric TWI
Prominent U waves
Hydrocephalus
Consider ventricular drain placement for deteriorating LOC + no improvement within 24 hours
Hyponatremia
Usually due to SIADH
Treat via isotonic, or if necessary, hypertonic saline (do not treat via water restriction!)

Hunt and Hess

Grade 0: Unruptured aneurysm

Grade 1: Asymptomatic or mild HA and slight nuchal rigidity

Grade 1a: No acute meningeal/brain reaction, with fixed neurological def

Grade 2: Moderate to severe headache, stiff neck, no neurologic deficit except cranial nerve palsy

Grade 3: Mild mental status change (drowsy or confused), mild focal neurologic deficit

Grade 4: Stupor or moderate to severe hemiparesis

Grade 5: Coma or decerebrate rigidity

Grade 1 or 2 have curable dz, if dx missed pts return w/ higher grade (ie 3 or 4), 2/3 will be dead or vegetative at 6 mos if grade 3 or 4!

7/09 PANI (Adapted from Lampe, Birnbaumer), UpToDate, EB Emergency Medicine, July 2009