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==Background==
==Background==
[[File:Meninges-en.svg|thumb|Anatomy of the meninges]]
*Bleeding into the subarachnoid space (between arachnoid and pia mater)
Defined as hemorrhage into the subarachnoid space (between the arachnoid membrane and the pia mater ). This may occur spontaneously, usually from a ruptured cerebral aneurysm, or may result from head injury.
*Ruptured cerebral aneurysm accounts for ~85% of nontraumatic SAH
===Epidemiology===
**Most common locations: anterior communicating artery (30%), posterior communicating artery (25%), MCA bifurcation (20%)
The prevalence of SAH in patients presenting with true thunderclap headache is estimated at ~10%. <ref>Dubosh NM et al. Sensitivity of Early Brain Computed Tomography to Exclude Aneurysmal Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis. Stroke 2016. PMID: 26797666</ref>
*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)


===Risk Factors===
==Clinical Features==
*Genetics (polycystic kidney disease, Ehler-Danlos, family history)  
*"Worst headache of my life" — sudden onset, maximal at onset (thunderclap headache)
*Hypertension
*'''Sentinel headache''': warning leak days-weeks before major rupture (present in ~30-50%)
*Atherosclerosis
*Meningismus (neck stiffness, photophobia) — may take 6-12 hours to develop
*Cigarette smoking
*Loss of consciousness at onset (~50%)
*[[Alcohol]]
*Nausea, vomiting (common)
*Age &gt;50
*Focal neurologic deficits (CN III palsy → posterior communicating artery aneurysm)
*[[Cocaine]] use
*Seizures (~10% at onset)
*Estrogen deficiency
*Terson syndrome: intraocular hemorrhage (subhyaloid/vitreous) associated with severe SAH
*'''May present as syncope, cardiac arrest, or altered mental status without headache'''


===Etiology of Spontaneous SAH===
===Hunt-Hess Grading===
*Ruptured aneurysm (85%)
*Grade I: asymptomatic or mild headache
*Nonaneurysmal (15%)
*Grade II: moderate-severe headache, nuchal rigidity, CN palsy
**Perimesencephalic hemorrhage (10%) - lower risk of complications
*Grade III: drowsiness, confusion, mild focal deficit
**Other: tumor, coagulopathy, dissection, vasculitis, SCD, venous sinus thrombosis
*Grade IV: stupor, moderate-severe hemiparesis
 
*Grade V: coma, decerebrate posturing
===Traumatic Subarachnoid Hemorrhage===
*Differentiate from aneurysmal rupture
*Supportive care with prevention of hypertension, elevated ICP, and vasospasm with PO nimodipine
*Observation and repeat head CT for stable patients
 
==Clinical Features==
*Sudden, severe [[headache]] that reaches maximal intensity within minutes (97% of cases)
**Sudden onset is more important finding than worst [[headache]]
*May be associated with [[syncope]], [[seizure]], [[nausea/vomiting]], meningismus
**Meningismus may not develop until hrs after bleed (blood breakdown -&gt; aseptic meningitis)
*[[Retinal hemorrhage]]
**May be the only clue in comatose patients
*Sentinel bleed headache 6-20 days before serious SAH in 30-50% of patients


==Differential Diagnosis==
==Differential Diagnosis==
{{Intracranial hemorrhage DDX}}
*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]]


===Other===
{{Headache DDX}}
*Drug toxicity
*Ischemic [[Stroke (Main)|Stroke]]
*[[Meningitis]]
*[[Encephalitis]]
*Intracranial tumor
*Intracranial hypotension
*Metabolic derangements
*[[Cerebral venous thrombosis]]
*Primary headache syndromes (benign thunderclap headache, [[Migraine]], [[Cluster Headache]])


==Evaluation==
==Evaluation==
[[File:SubarachnoidP.png|thumb|Noncontrast CT showing subarachnoid hemorrhage (white area in the center stretching into the sulci).]]
===Non-Contrast CT Head===
===Ottawa SAH Rules<ref>Ottawa SAH Rule JAMA. 2013 Sep 25;310(12):1248-55. doi: 10.1001/jama.2013.278018</ref>===
*First-line test
''Never has been externally and prospectively validated, authors caution implementation into routine use''
*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>
*100% sensitive to rule out SAH (97.1%-100%)
*Fisher grade: amount of blood predicts vasospasm risk
*Can exclude SAH if all of the following are true
*Modern thin-cut CT with experienced radiologist within 6 hours may approach 100% sensitivity
**Age < 40
**No Neck pain or stiffness
**No Witnessed LOC
**No onset during exertion
**No Thunderclap symptomatology (max intensity at onset)
**No limited neck flexion on physical exam


'''If concerned for SAH and CT normal strongly consider LP'''
===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


===Non-Contrast Head CT===
===Ottawa SAH Rule===
{| class="wikitable"
*For alert patients >15 years with new severe nontraumatic headache reaching maximum intensity within 1 hour
| align="center" style="background:#f0f0f0;"|'''Time from onset of symptoms'''
*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>:
| align="center" style="background:#f0f0f0;"|'''Sensitivity of CT'''
**Age ≥40
|-
**Neck pain or stiffness
| <6 hours||~100%<ref>Perry JJ, et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. BMJ. 2011; 343:d4277.
</ref>  
**Witnessed loss of consciousness
|-
**Onset during exertion
| 6-12 hours||98%
**Thunderclap headache (instant peak)
|-
**Limited neck flexion on exam
| 12-24 hours||93%<ref>van Gijn J and van Dongen KJ. The time course of aneurysmal haemorrhage on computed tomograms. Neuroradiology. 1982; 23:153–156.</ref>
|-
| 24 hours - 5 days||<60%
|}


*SAH due to aneurysm - look in cisterns (esp. suprasellar cistern)  
===CT Angiography (CTA)===
*SAH due to trauma - look at convexities of frontal and temporal cortices
*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


===Lumbar Puncture===
===Labs===
*Elevated RBC count that does not decrease from tube one to four
*CBC, BMP, coagulation studies (PT/INR, PTT)
**Note: decreasing RBCs in later tubes can occur in SAH; only reliable if RBC count in final tube is nl
*Type and screen
*Opening pressure &gt;20 (60% of patients)
*Troponin (neurogenic myocardial stunning)
**Can help differentiate from a traumatic tap (opening pressure expected to be normal)
*Finger stick glucose
**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
*If traumatic tap is suspected
**Tube 4 RBC count <500 has negative predictive value of 100% for SAH. Tube 4 RBC decrease of 70% compared to tube 1 excludes a radiographically detectable SAH.<ref>Gorchynski J, Oman J, and Newton T. Interpretation of traumatic lumbar punctures in the setting of possible subarachnoid hemorrhage: who can be safely discharged? Cal J Emerg Med. 2007; 8(1): 3–7.</ref>
**One study found that >2000 RBCs had a sensitivity of 93% and specificity of 93% for SAH, sensitivity increased to 100% when xanthochromia added.<ref>Perry JJ, Alyahya B, Sivilotti MLA, et al. Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study. BMJ : British Medical Journal. 2015;350:h568.</ref>
 
===CT Angiogram===
*A CT followed by CTA is an acceptable alternative to CT and LP<ref>Walsh B, Vilke GM, Coyne CJ. Clinical Guidelines for the Emergency Department Evaluation of Subarachnoid Hemorrhage. Meurer WJ, JEM. 2016; 50(4) 696-701.</ref>
*CTA has a 98% sensitivity for aneurysms >3mm


==Management==
==Management==
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.
===ED Management===
 
*ABCs, IV access, continuous monitoring
#Avoid hypotension
*Blood pressure control:
#*Maintain MAP>80 (CPP of 60 as long as ICP<20)
**Target SBP <160 mmHg until aneurysm secured (reduce rebleeding risk)
#*Give [[IVF]]
**Nicardipine infusion (5-15 mg/hr, titrate q5min) — preferred
#*Give [[pressors]] if IVF ineffective
**Labetalol 10-20 mg IV q10-20min
#Hypertension
**Avoid nitroprusside (increases ICP)
#*AHA/ASA has no formal recommendations but states that decreasing to SBP <160 is reasonable<ref>Connolly ES Jr, Rabinstein AA, Carhuapoma JR, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/american Stroke Association. Stroke. 2012; 43(6):1711-1737.</ref>
*Seizure management: benzodiazepines acutely; prophylactic AEDs controversial
#*Rapid SBP lowering <140 has been advocated with early research showing improved functional outcome<ref>Anderson CS, Heeley E, Huang Y, et al. Rapid blood-pressure lowering in patients with acute intracerebral hemorrhage. N Engl J Med. 2013; 368:2355-2365.</ref>, but more recent work has found no difference between SBP <140 and <180<ref>Qureshi AI, Palesch YY, Barsan WG, et al. Intensive Blood-Pressure Lowering in Patients with Acute Cerebral Hemorrhage. N Engl J Med. 2016; 1-11. [Epub ahead of print].</ref>
*Treat headache: acetaminophen; short-acting opioids cautiously
#*Ensure appropriate pain control and sedation before adding antihypertensives
**Avoid ketorolac (platelet inhibition)
#Discontinue/reverse all anticoagulation
*Aminocaproic acid (tranexamic acid): may reduce rebleeding risk before aneurysm secured — 4g IV loading dose (discuss with neurosurgery)
#*[[Coumadin]] --> (Prothrombin complex conc or [[FFP]]) + vitamin K
*Reverse anticoagulation if applicable
#*[[Aspirin]] --> [[DDAVP]]
#*[[Plavix]] --> [[Platelets]]
#*Dabigitran ([[Pradaxa]]) --> [[Idarucizumab]] (Praxbind): 5 grams IV
#[[Nimodipine]]
#*Only CCB studied that has been shown to prevent vasospasm (associated with 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
#[[Magneisum sulfate]]
#*Controversial; prevents vasospasm acting as NMDA antagonist and a calcium channel blocker; maintain between 2-2.5 mmol/L
#Seizure prophylaxis
#*Controversial; 3 day course may be preferable
#*[[Phenytoin]], [[levetiracetam]], [[carbamazepine]] and [[phenobarb]]. Phenytoin can be associated with worse neurologic & cognitive outcome
#Glucocorticoid therapy
#*Controversial; evidence suggests is neither beneficial nor harmful
#Glycemic control
#*Controversial; consider sliding scale if long patient stay in ED while awaiting ICU bed
#Keep head of bed elevated
#Aneurysm treatment
#*Surgical clipping and endovascular coiling are definitive treatment
#*Antifibrinolytic - Controversial; if delayed aneurysmal treatment, consider short term therapy (<72 hrs) with TXA or aminocaproic acid


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


{{AHA SAH BP Guidelines}}
===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==
==Disposition==
*Admit
*All confirmed SAH: emergent neurosurgical consultation and ICU admission
 
*Transfer to neurosurgical center if local capabilities unavailable
==Complications==
*SAH ruled out (negative CT + negative LP): may discharge with headache precautions and PCP follow-up
===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
**treatment for symptomatic vasospasm: Triple-H therapy (hemodilution + induced hypertension (pressors) + hypervolemia), balloon angioplasty, or intra-arterial vasodilators{{Citation needed|reason=Reliable source needed|date=February 2016}}
**Studies have not provided strong evidence of benefit Triple-H therapy{{Citation needed|reason=Reliable source needed|date=February 2016}}
 
===Cardiac abnormalities===
Most likely related to the 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 within 24hr


===[[Hyponatremia]]===
== Calculators ==
*[[Hyponatremia]] is seen in 10%-40% of the patients with subarachnoid hemorrhage who are admitted to the ICU.<ref>Woo, M.H, Kale-Pradhan, P.B. Fludrocortisone in the treatment
{{Ottawa SAH Calculator}}
of subarachnoid hemorrhage-induced hyponatremia. Annals of Pharmacotherapy. 1997.  31, 637–639.</ref>
{{Fisher Scale Calculator}}
*Cerebral Salt Wasting and [[SIADH]] are the two most common causes<ref>Albanese, A. et al. . Management of hyponatremia in patients with acute cerebral insults. Archives of Disease in Childhood, 85. (2001). 246–251.</ref>
 
==Prognosis==
===Hunt and Hess===
Subjective terminology, but good interobserver variability
{| class="wikitable"
| align="center" style="background:#f0f0f0;"|'''Grade'''
| align="center" style="background:#f0f0f0;"|'''Description'''
| align="center" style="background:#f0f0f0;"|'''Survival Rate'''
|-
|0 ||Unruptured aneurysm||-
|-
|1 ||Asymptomatic or mild HA and slight nuchal rigidity||70%
|-
|1a ||No acute meningeal/brain reaction, with fixed neurological def||-
|-
|2 ||Moderate to severe HA, stiff neck, no neurologic deficit except CN palsy||60%
|-
|3 ||Mild mental status change (drowsy or confused), mild focal neurologic deficit||50%
|-
|4 ||Stupor or moderate to severe hemiparesis||20%
|-
|5 ||Coma or decerebrate rigidity||10%
|}
 
:Grade 1 or 2 have curable disease
 
:Add one grade for serious systemic disease (hypertension, DM, severe atherosclerosis, COPD)
 
===World Federation of Neurosurgical Societies (WFNS)===
Objective terminology, and fair interobserver variability
{| class="wikitable"
|-
!width="50"| Grade
! GCS
! Focal neurological deficit
|-
! 1
| 15 || Absent
|-
! 2
| 13–14 || Absent
|-
! 3
| 13–14 || Present
|-
! 4
| 7–12 || Present or absent
|-
! 5
| <7 || Present or absent
|}
 
Other scales are also available, including the Ogilvy and Carter scale (comprehensive, yet complex), and the Fisher scale or Claassen grading system (vasospasm index risk).
 
Note: First-degree relatives are at 2-5 fold increase in SAH, so screening is considered on individual basis.


==See Also==
==See Also==
*[[Intracranial Hemorrhage (Main)]]
*[[Intracerebral hemorrhage]]
*[[Head Trauma]]
*[[Subdural hemorrhage]]
 
*[[Epidural hemorrhage]]
==External Links==
*[[Headache]]
*[http://emcrit.org/podcasts/sah/ EMCrit Podcast - Subarachnoid Hemorrhage]
*[[Thunderclap headache]]
*[[Lumbar puncture]]


==References==
==References==
<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
[[Category:Neurology]]
[[Category:Neurology]]
[[Category:Critical Care]]
[[Category:Neurosurgery]]

Revisión actual - 09:56 22 mar 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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