Subarachnoid hemorrhage: Difference between revisions
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== Background ==
==Background==
*Bleeding into the subarachnoid space (between arachnoid and pia mater)
*Ruptured cerebral aneurysm accounts for ~85% of nontraumatic SAH
**Most common locations: anterior communicating artery (30%), posterior communicating artery (25%), MCA bifurcation (20%)
*Other causes: arteriovenous malformation, perimesencephalic (benign, ~10%), vasculitis, coagulopathy, drug use
*Mortality: ~50% overall (25% die before reaching hospital, 25% die within 30 days)
*Risk factors:
**[[Hypertension]] (most important modifiable risk factor)
**Smoking, heavy alcohol use
**Family history of SAH or aneurysm (first-degree relative)
**Polycystic kidney disease, Ehlers-Danlos, connective tissue disorders
**Prior SAH (risk of rebleeding)
**Sympathomimetic drug use ([[cocaine]], [[amphetamines]])
*Peak incidence: age 40-60; female predominance (1.6:1)


=== Pearls ===
==Clinical Features==
*"Worst headache of my life" — sudden onset, maximal at onset (thunderclap headache)
*'''Sentinel headache''': warning leak days-weeks before major rupture (present in ~30-50%)
*Meningismus (neck stiffness, photophobia) — may take 6-12 hours to develop
*Loss of consciousness at onset (~50%)
*Nausea, vomiting (common)
*Focal neurologic deficits (CN III palsy → posterior communicating artery aneurysm)
*Seizures (~10% at onset)
*Terson syndrome: intraocular hemorrhage (subhyaloid/vitreous) associated with severe SAH
*'''May present as syncope, cardiac arrest, or altered mental status without headache'''


#Obtain GCS before intubation
===Hunt-Hess Grading===
#If intubate prevent hypertension (rebleeding)
*Grade I: asymptomatic or mild headache
##Pretreatment
*Grade II: moderate-severe headache, nuchal rigidity, CN palsy
###Lidocaine 1-1.5mg/kg (100mg) (blunts incr in BP)
*Grade III: drowsiness, confusion, mild focal deficit
###Fentanyl 200mcg (sympatholytic)
*Grade IV: stupor, moderate-severe hemiparesis
##Sedation
*Grade V: coma, decerebrate posturing
###If pt has high BP - use propofol
###If pt has good BP - use etomidate
#Treat pain
##Prevents incr catacholamines/ incr BP


=== Epidemiology ===
==Differential Diagnosis==
*Primary [[headache]] (migraine, tension, cluster)
*[[Meningitis]] / [[encephalitis]]
*[[Intracerebral hemorrhage]]
*[[Cerebral venous sinus thrombosis]]
*[[Hypertensive emergency]]
*Reversible cerebral vasoconstriction syndrome (RCVS)
*[[Cervical artery dissection]]
*[[Pituitary apoplexy]]


Of All pts in ED with c/o HA:
{{Headache DDX}}


*1% will have SAH
==Evaluation==
*10% will have SAH if c/o worst HA of life
===Non-Contrast CT Head===
*25% will have SAH if c/o worst HA of life + any neuro deficit
*First-line test
*Sensitivity ~98% within 6 hours of onset, ~93% at 12 hours, decreasing to ~50% by day 5-7<ref>Perry JJ, et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage. ''BMJ''. 2011;343:d4277. PMID 21768192</ref>
*Fisher grade: amount of blood predicts vasospasm risk
*Modern thin-cut CT with experienced radiologist within 6 hours may approach 100% sensitivity


=== Risk Factors ===
===Lumbar Puncture===
*Required if CT negative and clinical suspicion remains
*Classic finding: xanthochromia (yellow discoloration from bilirubin in CSF)
**Takes 6-12 hours to develop — LP performed <6 hours after onset may miss xanthochromia
*'''Elevated RBCs that do NOT clear''' across sequential tubes (vs traumatic tap which clears)
*Elevated opening pressure
*Traumatic tap vs SAH: controversial; visual xanthochromia and clinical context are most important


(in order of relative risk)  
===Ottawa SAH Rule===
*For alert patients >15 years with new severe nontraumatic headache reaching maximum intensity within 1 hour
*100% sensitivity (validation study) — if none present, SAH effectively ruled out<ref>Perry JJ, et al. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. ''JAMA''. 2013;310(12):1248-1255. PMID 24065011</ref>:
**Age ≥40
**Neck pain or stiffness
**Witnessed loss of consciousness
**Onset during exertion
**Thunderclap headache (instant peak)
**Limited neck flexion on exam


#Genetics (polycystic kidney disease, Ehler-Danlos, family hx)  
===CT Angiography (CTA)===
#Hypertension
*Obtain with initial CT if SAH confirmed or high suspicion
#Atherosclerosis
*Identifies aneurysm location and morphology for surgical/endovascular planning
#Cigarette smoking
*Sensitivity >95% for aneurysms >3 mm
#Alcohol
#Age &gt; 50
#Cocaine use
#Estrogen deficiency


== Clinical Manifestations ==
===Labs===
*CBC, BMP, coagulation studies (PT/INR, PTT)
*Type and screen
*Troponin (neurogenic myocardial stunning)
*Finger stick glucose


#Sudden, severe headache (97% of cases)
==Management==
##Sudden onset is more important finding than worst HA
===ED Management===
#May be associated with syncope, seizure, nausea/vomiting, and meningismus
*ABCs, IV access, continuous monitoring
##Meningismus may not develop until several hours after bleed (caused by blood breakdown &gt; aseptic meningitis)  
*Blood pressure control:
#Retinal hemorrhages
**Target SBP <160 mmHg until aneurysm secured (reduce rebleeding risk)
##May be the only clue in comatose patients
**Nicardipine infusion (5-15 mg/hr, titrate q5min) — preferred
#Approximately 30-50% will have sentinel bleed/HA 6-20 days before SAH
**Labetalol 10-20 mg IV q10-20min
**Avoid nitroprusside (increases ICP)
*Seizure management: benzodiazepines acutely; prophylactic AEDs controversial
*Treat headache: acetaminophen; short-acting opioids cautiously
**Avoid ketorolac (platelet inhibition)
*Aminocaproic acid (tranexamic acid): may reduce rebleeding risk before aneurysm secured — 4g IV loading dose (discuss with neurosurgery)
*Reverse anticoagulation if applicable


== Diagnosis ==
===Definitive Treatment===
*Neurosurgery/neurointerventional consultation emergently
*Aneurysm securing (within 24 hours ideally):
**Endovascular coiling (preferred for most aneurysms) OR
**Surgical clipping
*ICU admission


#Non-Contrast Head CT
===Complications (Post-Hemorrhage)===
##90%-98% specific if performed w/in 24 hours of bleed
*'''Rebleeding''': highest risk in first 24 hours (~4%); '''most devastating complication'''
##91% sensitive in patients w/ normal neuro exam
*Vasospasm: occurs days 3-14 (peak day 7); monitor with daily TCDs
###Decreases to ~50% sensitive by day 5
**Treat with nimodipine 60 mg PO/NG q4h x 21 days (improves outcomes; does not prevent vasospasm)
##Not as sensitive/specific for minor bleeds
**Triple-H therapy (hypertension, hypervolemia, hemodilution) — only after aneurysm secured
##SAH 2/2 aneurysm (90%) - look in cisterns (especially suprasellar cistern)
*Hydrocephalus: acute (requires EVD) or chronic (VP shunt)
##SAH 2/2 trauma - Look at convexities of frontal &amp; temporal cortices
*Hyponatremia: cerebral salt wasting vs SIADH
#Lumbar Puncture
*Neurogenic cardiac dysfunction: Takotsubo-like, neurogenic pulmonary edema
##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 &gt; 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


<br>
==Disposition==
*All confirmed SAH: emergent neurosurgical consultation and ICU admission
*Transfer to neurosurgical center if local capabilities unavailable
*SAH ruled out (negative CT + negative LP): may discharge with headache precautions and PCP follow-up


== Treatment  ==
== Calculators ==
{{Ottawa SAH Calculator}}
{{Fisher Scale Calculator}}


#Nimodipine
==See Also==
##Associated with improved neuro outcomes and decreased cerebral infarction
*[[Intracerebral hemorrhage]]
##Give 60mg q4hr PO or NGT only! (never IV)
*[[Subdural hemorrhage]]
#BP control
*[[Epidural hemorrhage]]
##No consensus on HTN (incr BP may maintain CPP but may also increase rate of bleeding)
*[[Headache]]
###If pt is alert this means CPP is adequate so consider lowering sbp to 120-140
*[[Thunderclap headache]]
####If pt has history of HTN consider lowering sbp to ~160
*[[Lumbar puncture]]
###If pt is ALOC consider leaving BP alone as the ALOC may be 2/2 reduced CPP
##If BP control is necessary use NICARDIPINE, LABETALOL, or ESMOLOL
###Avoid vasodilators such as nitroprusside or NTG (increase cerebral blood volume &gt; increased ICP)
##Avoid hypotension
###Maintain MAP &gt; 80
####Give IVF
####Give pressors if IVF ineffective
#Discontinue/reverse all anticoagulation
##Coumadin - give (prothrombin complex conc or FFP) and vit K)
##Aspirin - give DDAVP
##Plavix - give platelets
#Seizure prophylaxis
##Controversial; 3 day course may be preferable
##Phenytoin load
#Glucocorticoid therapy
##Controversial; evidence suggests is neither beneficial nor harmful
#Glycemic control
##Controversial; consider sliding scale if long pt stay in ED while awaiting ICU bed


== Complications ==
==References==
<references/>
*Connolly ES Jr, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline from the AHA/ASA. ''Stroke''. 2012;43(6):1711-1737. PMID 22556195
*Edlow JA, et al. Diagnosis of subarachnoid hemorrhage. ''Stroke''. 2023;54(4):1058-1072. PMID 36848423
*van Gijn J, et al. Subarachnoid haemorrhage. ''Lancet''. 2007;369(9558):306-318. PMID 17258671


#Rebleeding
[[Category:Neurology]]
##Risk is highest within first 24 hours (2.5-4%), particularly within first 6 hours
[[Category:Critical Care]]
##Usually diagnosed by CT after acute deterioration in neuro status
[[Category:Neurosurgery]]
##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!)
 
== Prognosis ==
 
=== 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!
 
^Add one grade for serious systemic dz (HTN, DM, severe atherosclerosis, COPD)
 
=== World Federation of Neurosurgical Societies (WFNS) ===
 
{| cellspacing="1" cellpadding="1" border="1" width="200"
|-
| '''Grade'''<br>
| '''GCS'''<br>
| '''Major Focal Deficit'''<br>
|-
| 0&nbsp;(unruptured)<br>
| NA<br>
| NA<br>
|-
| 1<br>
| 15<br>
| Absent<br>
|-
| 2<br>
| 13-14<br>
| Absent<br>
|-
| 3<br>
| 13-14<br>
| Present<br>
|-
| 4<br>
| 7-12<br>
| Present/absent<br>
|-
| 5<br>
| 3-6<br>
| Present/absent<br>
|}
 
<br>
 
== See Also ==
 
[[Intracranial Hemorrhage]]  
 
== Source ==
 
UpToDate
 
EB Emergency Medicine, July 2009
 
EMCrit Podcast 8
 
[[Category:Neuro]]

Latest revision as of 09:56, 22 March 2026

Background

  • Bleeding into the subarachnoid space (between arachnoid and pia mater)
  • Ruptured cerebral aneurysm accounts for ~85% of nontraumatic SAH
    • Most common locations: anterior communicating artery (30%), posterior communicating artery (25%), MCA bifurcation (20%)
  • Other causes: arteriovenous malformation, perimesencephalic (benign, ~10%), vasculitis, coagulopathy, drug use
  • Mortality: ~50% overall (25% die before reaching hospital, 25% die within 30 days)
  • Risk factors:
    • Hypertension (most important modifiable risk factor)
    • Smoking, heavy alcohol use
    • Family history of SAH or aneurysm (first-degree relative)
    • Polycystic kidney disease, Ehlers-Danlos, connective tissue disorders
    • Prior SAH (risk of rebleeding)
    • Sympathomimetic drug use (cocaine, amphetamines)
  • Peak incidence: age 40-60; female predominance (1.6:1)

Clinical Features

  • "Worst headache of my life" — sudden onset, maximal at onset (thunderclap headache)
  • Sentinel headache: warning leak days-weeks before major rupture (present in ~30-50%)
  • Meningismus (neck stiffness, photophobia) — may take 6-12 hours to develop
  • Loss of consciousness at onset (~50%)
  • Nausea, vomiting (common)
  • Focal neurologic deficits (CN III palsy → posterior communicating artery aneurysm)
  • Seizures (~10% at onset)
  • Terson syndrome: intraocular hemorrhage (subhyaloid/vitreous) associated with severe SAH
  • May present as syncope, cardiac arrest, or altered mental status without headache

Hunt-Hess Grading

  • Grade I: asymptomatic or mild headache
  • Grade II: moderate-severe headache, nuchal rigidity, CN palsy
  • Grade III: drowsiness, confusion, mild focal deficit
  • Grade IV: stupor, moderate-severe hemiparesis
  • Grade V: coma, decerebrate posturing

Differential Diagnosis

Headache

Common

Killers

Maimers

Others

Aseptic Meningitis

Evaluation

Non-Contrast CT Head

  • First-line test
  • Sensitivity ~98% within 6 hours of onset, ~93% at 12 hours, decreasing to ~50% by day 5-7[1]
  • Fisher grade: amount of blood predicts vasospasm risk
  • Modern thin-cut CT with experienced radiologist within 6 hours may approach 100% sensitivity

Lumbar Puncture

  • Required if CT negative and clinical suspicion remains
  • Classic finding: xanthochromia (yellow discoloration from bilirubin in CSF)
    • Takes 6-12 hours to develop — LP performed <6 hours after onset may miss xanthochromia
  • Elevated RBCs that do NOT clear across sequential tubes (vs traumatic tap which clears)
  • Elevated opening pressure
  • Traumatic tap vs SAH: controversial; visual xanthochromia and clinical context are most important

Ottawa SAH Rule

  • For alert patients >15 years with new severe nontraumatic headache reaching maximum intensity within 1 hour
  • 100% sensitivity (validation study) — if none present, SAH effectively ruled out[2]:
    • Age ≥40
    • Neck pain or stiffness
    • Witnessed loss of consciousness
    • Onset during exertion
    • Thunderclap headache (instant peak)
    • Limited neck flexion on exam

CT Angiography (CTA)

  • Obtain with initial CT if SAH confirmed or high suspicion
  • Identifies aneurysm location and morphology for surgical/endovascular planning
  • Sensitivity >95% for aneurysms >3 mm

Labs

  • CBC, BMP, coagulation studies (PT/INR, PTT)
  • Type and screen
  • Troponin (neurogenic myocardial stunning)
  • Finger stick glucose

Management

ED Management

  • ABCs, IV access, continuous monitoring
  • Blood pressure control:
    • Target SBP <160 mmHg until aneurysm secured (reduce rebleeding risk)
    • Nicardipine infusion (5-15 mg/hr, titrate q5min) — preferred
    • Labetalol 10-20 mg IV q10-20min
    • Avoid nitroprusside (increases ICP)
  • Seizure management: benzodiazepines acutely; prophylactic AEDs controversial
  • Treat headache: acetaminophen; short-acting opioids cautiously
    • Avoid ketorolac (platelet inhibition)
  • Aminocaproic acid (tranexamic acid): may reduce rebleeding risk before aneurysm secured — 4g IV loading dose (discuss with neurosurgery)
  • Reverse anticoagulation if applicable

Definitive Treatment

  • Neurosurgery/neurointerventional consultation emergently
  • Aneurysm securing (within 24 hours ideally):
    • Endovascular coiling (preferred for most aneurysms) OR
    • Surgical clipping
  • ICU admission

Complications (Post-Hemorrhage)

  • Rebleeding: highest risk in first 24 hours (~4%); most devastating complication
  • Vasospasm: occurs days 3-14 (peak day 7); monitor with daily TCDs
    • Treat with nimodipine 60 mg PO/NG q4h x 21 days (improves outcomes; does not prevent vasospasm)
    • Triple-H therapy (hypertension, hypervolemia, hemodilution) — only after aneurysm secured
  • Hydrocephalus: acute (requires EVD) or chronic (VP shunt)
  • Hyponatremia: cerebral salt wasting vs SIADH
  • Neurogenic cardiac dysfunction: Takotsubo-like, neurogenic pulmonary edema

Disposition

  • All confirmed SAH: emergent neurosurgical consultation and ICU admission
  • Transfer to neurosurgical center if local capabilities unavailable
  • SAH ruled out (negative CT + negative LP): may discharge with headache precautions and PCP follow-up

Calculators

Template:Ottawa SAH Calculator

Modified Fisher Scale

Modified Fisher Scale — SAH Vasospasm Risk
CT Findings Select Grade
Grade

1 Grade 0 — No SAH or IVH (0)

Grade 1 — Thin SAH, no IVH (1)

Grade 2 — Thin SAH with IVH (2)

Grade 3 — Thick SAH, no IVH (3)

Grade 4 — Thick SAH with IVH (4)

Modified Fisher Grade
Interpretation — Risk of Symptomatic Vasospasm
Grade Vasospasm Risk Description
0 | ~0% | No subarachnoid blood detected.
1 | ~24% | Focal or diffuse thin SAH, no intraventricular hemorrhage (IVH).
2 | ~33% | Focal or diffuse thin SAH with IVH.
3 | ~33% | Focal or diffuse thick SAH (>1mm), no IVH.
4 | ~40% | Focal or diffuse thick SAH with IVH. Highest vasospasm risk.
References
  • Fisher CM, Kistler JP, Davis JM. Relation of cerebral vasospasm to subarachnoid hemorrhage visualized by computerized tomographic scanning. Neurosurgery. 1980;6(1):1-9. PMID 7354892.
  • Frontera JA, Claassen J, Schmidt JM, et al. Prediction of symptomatic vasospasm after subarachnoid hemorrhage: the modified Fisher scale. Neurosurgery. 2006;59(1):21-27. PMID 16823296.

See Also

References

  1. ↑ Perry JJ, et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage. BMJ. 2011;343:d4277. PMID 21768192
  2. ↑ Perry JJ, et al. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013;310(12):1248-1255. PMID 24065011
  • Connolly ES Jr, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline from the AHA/ASA. Stroke. 2012;43(6):1711-1737. PMID 22556195
  • Edlow JA, et al. Diagnosis of subarachnoid hemorrhage. Stroke. 2023;54(4):1058-1072. PMID 36848423
  • van Gijn J, et al. Subarachnoid haemorrhage. Lancet. 2007;369(9558):306-318. PMID 17258671
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