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 HTN (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 adequate 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 who p/w HA:
{{Headache DDX}}
**1% will have SAH
**10% will have SAH if c/o worst HA of life
**25% will have SAH if c/o worst HA of life + any neuro deficit


=== Risk Factors  ===
==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<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


#Genetics (polycystic kidney disease, Ehler-Danlos, family hx)  
===Lumbar Puncture===
#Hypertension
*Required if CT negative and clinical suspicion remains
#Atherosclerosis
*Classic finding: xanthochromia (yellow discoloration from bilirubin in CSF)
#Cigarette smoking
**Takes 6-12 hours to develop — LP performed <6 hours after onset may miss xanthochromia
#Alcohol
*'''Elevated RBCs that do NOT clear''' across sequential tubes (vs traumatic tap which clears)
#Age &gt;50
*Elevated opening pressure
#Cocaine use
*Traumatic tap vs SAH: controversial; visual xanthochromia and clinical context are most important
#Estrogen deficiency


=== Etiology of Spontaneous SAH ===
===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


#Ruptured aneurysm (85%)  
===CT Angiography (CTA)===
#Nonaneurysmal (15%)
*Obtain with initial CT if SAH confirmed or high suspicion
##Perimesencephalic hemorrhage (10%)
*Identifies aneurysm location and morphology for surgical/endovascular planning
##Other: tumor, coagulopathy, dissection, vasculitis, SCD, venous sinus thrombosis
*Sensitivity >95% for aneurysms >3 mm


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


#Sudden, severe headache that reaches maximal intensity within minutes (97% of cases)
==Management==
##Sudden onset is more important finding than worst HA
===ED Management===
#May be a/w syncope, seizure, nausea/vomiting, meningismus
*ABCs, IV access, continuous monitoring
##Meningismus may not develop until hrs after bleed (blood breakdown -&gt; aseptic meningitis)
*Blood pressure control:
#Retinal hemorrhage
**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
#Sentinel bleed/HA 6-20d before SAH (30-50% of pts)
**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


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


#Other intracranial hemorrhage
===Complications (Post-Hemorrhage)===
#Drug toxicity
*'''Rebleeding''': highest risk in first 24 hours (~4%); '''most devastating complication'''
#Ischemic stroke
*Vasospasm: occurs days 3-14 (peak day 7); monitor with daily TCDs
#Meningitis
**Treat with nimodipine 60 mg PO/NG q4h x 21 days (improves outcomes; does not prevent vasospasm)
#Encephalitis
**Triple-H therapy (hypertension, hypervolemia, hemodilution) — only after aneurysm secured
#Intracranial tumor
*Hydrocephalus: acute (requires EVD) or chronic (VP shunt)
#Intracranial hypotension
*Hyponatremia: cerebral salt wasting vs SIADH
#Metabolic derangements
*Neurogenic cardiac dysfunction: Takotsubo-like, neurogenic pulmonary edema
#Venous thrombosis
#Primary headache syndromes (benign thunderclap headache, migraine, cluster headache)


== Diagnosis  ==
==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


'''If concerned for SAH and CT normal strongly consider LP'''
== Calculators ==
{{Ottawa SAH Calculator}}
{{Fisher Scale Calculator}}


#Non-Contrast Head CT
==See Also==
##Sensitivity
*[[Intracerebral hemorrhage]]
###Within 12hr of onset of symptoms: 98% Sn
*[[Subdural hemorrhage]]
###Within 24hr of onset of symptoms: 93% Sn
*[[Epidural hemorrhage]]
###Within 5d of onset of symptoms: 50% Sn
*[[Headache]]
###Not as sensitive/specific for minor bleeds
*[[Thunderclap headache]]
##Findings
*[[Lumbar puncture]]
###SAH due to aneurysm - look in cisterns (esp. suprasellar cistern)
###SAH due to trauma - look at convexities of frontal and temporal cortices
#Lumbar Puncture
##Findings:
###Elevated RBC count that doesn't decrease from tube one to four
####Note: decreasing RBCs in later tubes can occur in SAH; only reliable if RBC count in final tube is nl
###Opening pressure &gt;20 (60% of pts)
####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 2hr after bleed to develop (beware of false negative if measure early)
####Sn (93%) / Sp (95%) highest after 12hr
##If unable to obtain CSF consider CTA
###CTA also highly sensitive for predicting delayed cerebral ischemia


== Treatment  ==
==References==
Physiologic derangements, such as hypoxemia, metabolic acidosis, hyperglycemia, BP instability, and fever, can worsen brain injury and has been independently associated with increased M&M, but no studies showing benefit of corrections.
<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


#BP control
[[Category:Neurology]]
##No consensus on HTN (incr BP may maintain CPP but may also increase rate of bleeding)
[[Category:Critical Care]]
###If pt is alert this means CPP is adequate so consider lowering SBP to 120-140
[[Category:Neurosurgery]]
####If pt has history of HTN consider lowering SBP to ~160
###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 (incr cerebral blood volume -&gt; incr ICP)
##Avoid hypotension
###Maintain MAP &gt;80
####Give IVF
####Give pressors if IVF ineffective
#Discontinue/reverse all anticoagulation
##Coumadin - (Prothrombin complex conc or FFP) + vit K
##Aspirin - DDAVP
##Plavix - Platelets
#Nimodipine
##Prevents vasospasm (a/w improved neuro outcomes and decreased cerebral infarction)
##Give 60mg q4hr PO or NGT only (never IV) within 96hr of symptom onset. NNT 13 to prevent one poor outcome
##Keep an eye on BP for fluctuations
#Seizure prophylaxis
##Controversial; 3 day course may be preferable
##Keppra preferred. Phenytoin a/w worse neurologic & cognitive outcome
#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
#Keep head of bed elevated
#Aneurysm Tx
##Surgical clipping and endovascular coiling are definitive tx
##Antifibrinolytic - Controversial; if delayed aneurysmal tx, consider short term therapy (<72 hrs) with TXA or aminocaproic acid
 
== Complications  ==
 
#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 started after aneurysm has been treated (surgery or intraluminal tx)
###Tx for symptomatic vasospasm: Triple-H therapy (hemodilution + induced hypertension (pressors) + hypervolemia), ballon angioplasty, or intra-arterial vasodilators.
####Studies have not provided strong evidence of benefit Triple-H therapy
#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/flutter
##QT prolongation
##Deep, symmetric TWI
##Prominent U waves
#Hydrocephalus
##Consider ventricular drain placement for deteriorating LOC + no improvement w/in 24hr
#Hyponatremia
##Usually due to SIADH
###Treat via isotonic, or if necessary, hypertonic saline (do not treat via H2O restriction)
##Rarely due to cerebral salt-wasting
###Volume depleted, so treat with isotonic saline
 
== 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 HA, stiff neck, no neurologic deficit except CN 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
 
<br>
 
*Grade 1 or 2 have curable disease
*Add one grade for serious systemic disease (HTN, DM, severe atherosclerosis, COPD)
 
=== World Federation of Neurosurgical Societies (WFNS)  ===
 
*Grade 1: GCS of 15, no motor deficits
*Grade 2: GCS of 13 or 14, no motor deficits
*Grade 3: GCS of 13 or 14, with motor deficits
*Grade 4: GCS of 7–12, with or without motor deficits
*Grade 5: GCS of 3–6, with or without motor deficits
 
First-degree relatives are at 2-5 fold increase in SAH, so screening is possibility.
 
== See Also  ==
*[[Intracranial Hemorrhage (Main)]]
*[[Head Trauma]]
 
== Source  ==
*UpToDate
*EB Emergency Medicine, July 2009
*EMCrit Podcast 8
*Tintinalli
*www.epmonthly.com/features/current-features/lp-for-subarachnoid-hemorrhage-the-700-club
 
[[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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