II. Epidemiology

  1. Represent 10% of all Cerebrovascular Accidents
  2. Represents 1-3% of Headache presentations to U.S. emergency departments (20,000 cases/year)
    1. Subarachnoid Hemorrhage diagnosis is missed in up to 30% of cases on initial evaluation

III. Causes

  1. Cerebral Aneurysm (e.g. Berry Aneurysm) rupture
    1. Incidence: 50 per 100,000 patients over age 30 years old
    2. Age: Rupture peaks at 40-60 years old (mean age 53 years old)
    3. Gender: Women represent 70% of ruptured SAH
    4. Higher Incidence in African American
  2. Congenital Arteriovenous Malformation (AVM)
    1. Most common cause of Subarachnoid Hemorrhage in children (rare event)
  3. Trauma
    1. See Head Injury
    2. Fall with Head Injury in the elderly
    3. Motor Vehicle Accident in younger patients

IV. Risk factors

V. Symptoms

  1. Classic presentation (highly suggestive of Subarachnoid Hemorrhage)
    1. Thunderclap Headache
    2. Vomiting
    3. Altered Level of Consciousness
  2. Headache Characteristics: Severe, sudden, atypical and unrelenting
    1. Sudden onset Thunderclap Headache
    2. "Worst Headache of my life" (+LR 1.20, less predictive than other red flags as below)
    3. Headache reaches maximum intensity in minutes (<10 to 60 minutes)
    4. Continued unrelenting Headache
    5. Headache different in characteric than prior Headaches (or no Headache History previously)
      1. Different location is less predictive of SAH
      2. Inadequate pain response to typical Headache Management is less predictive of SAH
      3. Adequate Headache response to analgesia does not exclude Subarachnoid Hemorrhage
  3. Headache regions most common
    1. Orbital Headache
    2. Occipital Headache with neck stiffness
  4. Associated symptoms
    1. Nausea and Vomiting (75% of cases)
    2. Dizziness
    3. Loss of consciousness (may be fleetingly brief) at Headache onset
    4. Altered Level of Consciousness
    5. Transient motor deficits (e.g. buckling of legs)
    6. Vision change
    7. Incoordination
    8. Seizure
  5. Initial herald bleed (sentinel Hemorrhage)
    1. Warning leak of small volume
    2. May precede full Cerebral Aneurysm rupture in >30-50% of cases
    3. Present as atypical, new or different Headaches with rapid onset
      1. May last days at a time
      2. May occur weaks before a major SAH

VI. Signs

  1. Identify subtle focal neurologic changes
    1. Anterior Cerebral Artery CVA
    2. Middle Cerebral Artery CVA
    3. Vertebro-Basilar CVA
    4. Posterior Cerebral Artery CVA
    5. Posterior Inferior Cerebellar Artery CVA
  2. Meningismus (e.g. Nuchal Rigidity)
  3. Ocular Motor Nerve palsy (especially third Cranial Nerve palsy)
  4. Ataxia
  5. Fundoscopic exam
    1. Papilledema
    2. Subhyaloid Hemorrhage (red blood layering behind the eye)
    3. Intraocular Hemorrhage (found in 1 in 7 patients with Subarachnoid Hemorrhage)

VIII. Grading: Hunt and Hess Classification

  1. Grade 1: Minimal Headache, slightly stiff neck (may represent sentinel bleed)
  2. Grade 2: Moderate to severe Headache, stiff neck, Cranial Nerve palsy
  3. Grade 3: Drowsy
  4. Grade 4: Stuporous. Moderate to severe Hemiparesis
  5. Grade 5: Deep coma. Decerebrate rigidity
  6. Hunt (1968) J Neurosurg 28(1): 14-20 [PubMed]

IX. Precautions: Red Flags suggestive of further evaluation for SAH

  1. Ottawa Subarachnoid Hemorrhage Rule (all absent excludes nearly 100% of SAH cases)
    1. Age over 40 years old
    2. Witnessed loss of consciousness (+LR: 3.77)
    3. Neck Pain or stiffness (more suggestive of severe SAH, +LR 2.29)
    4. Limited neck flexion on exam
    5. Thunderclap headadache (severity peaks rapidly, within 15-60 minutes)
    6. Onset during exertion (Exertional Headache, +LR 2.16)
  2. Other red flag findings (outside Ottawa Rules)
    1. Arrival to Emergency Department via Ambulance
    2. Hypertension (>160/100)
  3. References
    1. Landtblom (2002) Cephalgia 22(5): 354-60 [PubMed]
    2. Perry (2010) BMJ 341: c5204 +PMID:21030443 [PubMed]
    3. Perry (2013) JAMA 310(12):1248-55 +PMID:24065011 [PubMed]

X. Course

  1. Subarachnoid Hemorrhage diagnosed at initial medical contact
    1. Good or excellent outcome: 91% (contrast with 53% for incorrect initial diagnosis)
    2. Mayer (1996) Stroke 27(9): 1558-63 [PubMed]
  2. Missed Subarachnoid Hemorrhage
    1. Mortality risk at 2 hours: 20%
    2. Mortality risk at 7 days: 40%
    3. Rebleeding risk: 20% in first 2 weeks (1.5% risk per day)

XI. Differential Diagnosis

  1. See Headache Red Flag (includes Thunderclap Headache)
  2. See Headache Causes
  3. Tension Headaches may present in similar fashion to a herald bleed
    1. Do not miss herald bleed phase of Subarachnoid Hemorrhage

XII. Diagnosis

  1. CT Head without contrast
    1. Overall misses 5% of Subarachnoid Hemorrhage (may be 2% with new 5th generation CT scans)
      1. False Negative Rate increases if Hemoglobin <10 g/dl (results in isodense SAH appearance)
      2. False Negative Rate also increased with delay of CT from time from onset of Headache (see below)
      3. Despite this, ED physicians performed CT without LP in 50% of "worst Headache of life" patients
        1. Morgenstern (1998) Ann Emerg Med 32(3 Pt 1): 297-304 [PubMed]
    2. Third generation CT scans read by a qualified radiologist are very accurate when performed early after Headache
      1. CT Head within 6 hours of acute onset severe Headache in neurologically intact patient
        1. Test Sensitivity and Specificity were 100%
        2. Perry (2011) BMJ 343: d4277 [PubMed]
        3. Backes (2012) Stroke 43(8): 2115-9 [PubMed]
      2. Caveats
        1. Lumbar Puncture should still be performed after negative CT Head in high suspicion cases
        2. Studies excluded high risk patients
          1. Neurologic deficits
          2. Prior Subarachnoid Hemorrhage
          3. Papilledema
          4. Ventricular Shunt
          5. Brain Neoplasms
        3. Backes paper was in Netherlands at referral center
          1. High SAH Incidence, with imaging read by neuroradiology
        4. Reviews of the Perry paper suggest flaws (inconsistent follow-up and LP protocol)
          1. Newman (2012) EM:RAP 12(3): 6-7
        5. Later study showed 5% miss rate with early CT Head
          1. Perry (2020) Stroke 51(2):424-30 PMID:31805846 [PubMed]
      3. Indications for Head CT without LP (expert opinion)
        1. Head CT within 6 hours of Thunderclap Headache onset AND
        2. Normal Neurologic Exam AND
        3. CT read by radiologist AND
        4. No Neck Pain (Head CT may miss spinal AVM) AND
        5. Informed Consent with reliable patient
          1. Risk of missed SAH on CT Head alone is at least 1 in 700 within first 6 hours
        6. Edlow (2012) Stroke 43(8): 2031-2 [PubMed]
    3. Head CT Test Sensitivity for SAH decreases within days of event (most sensitive closest to Headache onset)
      1. CT sensitivity decreases after first 6-12 hours
      2. Day 3: 95% Test Sensitivity
      3. Day 5: 85% Test Sensitivity
      4. Day 7: 50% Test Sensitivity
      5. Day 14: 30% Test Sensitivity
  2. Lumbar Puncture
    1. Indicated for high clinical suspicion for SAH but negative CT Head (esp. >6 hours from Headache onset)
    2. Most useful in Hunt and Hess Scale 1 and 2 (more severe events are typically seen on CT)
    3. Findings consistent with Subarachnoid Hemorrhage
      1. CSF RBCs: >2000 within 2-12 hours after Headache
      2. CSF Leukocytes and Protein may also be increased
      3. Xanthochromia in centrifuged Cerebrospinal fluid (may be absent in first 12 hours)
        1. Most sensitive CSF finding for SAH
    4. Efficacy for diagnosis of SAH
      1. Perry study used<2000 CSF RBCs in last tube AND no Xanthochromia
        1. Negative Predictive Value: 100%
        2. Test Sensitivity: 100%
        3. Test Specificity: 91.2%
        4. Perry (2015) BMJ 350:h568 +PMID:25694274 [PubMed]
      2. Dupont study used <100 CSF RBCs in last tube AND no Xanthochromia
        1. Negative Predictive Value: 99%
        2. Test Sensitivity: 93%
        3. Test Specificity: 95%
        4. Dupont (2008) Mayo Clin Proc 83(12): 1326-31 [PubMed]
    5. SAH diagnosis made by LP when CT Head was negative
      1. True positive Lumbar Puncture for SAH: 0.4% (PPV 9.8%)
      2. False positive Lumbar Puncture: 4.2%
      3. Sayer (2015) Acad Emerg Med 22(11): 1267-73 +PMID:26480290 [PubMed]
  3. Cerebral CT Angiogram (CTA)
    1. Indicated for equivocal Lumbar Puncture (differentiate from bloody tap)
    2. Avoid using CTA instead of LP
      1. CT increases risk to 1% for False Positives (small insignificant aneurysms)
      2. Incidental, unrelated aneurysms are identified in 2.3% of patients
      3. CT Angiogram is poorly sensitive for blood
      4. Unnecessary radiation exposure
      5. LP remains the standard of care for ruling out Subarachnoid Hemorrhage
        1. Indicated when clinical suspicion is high, but noncontrast CT Head is normal
      6. Bederson (2009) Stroke 40(3): 994-1025 [PubMed]
      7. Worrall in Majoewsky (2012) EM:Rap 12(12): 3 [PubMed]
    3. Efficacy: Aneurysms 4 mm or larger
      1. Test Specificity: 100%
      2. Tests Sensitivity: 96-99.7%
  4. Catheter angiography
    1. Indicated by neurosurgery to identify source of bleeding if not identified on CTA
    2. Source may not be identified in up to 20-25% of cases with first catheter angiography
      1. Repeat catheter angiography in 7 days if initial angiography negative for SAH aneurysmal source
  5. Magnetic Resonance Imaging
    1. May be an alternative to non-contrast Head CT in a stable patient
    2. Consider in delayed presentation due to its sustained abnormal patterns after SAH (see efficacy below)
      1. MRI Test Sensitivity for SAH increases with time (while CT Head sensitivity decreases after 6 hours)
    3. Disadvantages compared with Head CT
      1. Much longer acquisition times are not viable for an unstable patient
      2. CT Head is better at imaging acute Intracerebral Hemorrhage
    4. Efficacy
      1. Flair Sequences
        1. Day 0 to 5 of Headache: 100% Test Sensitivity for SAH
        2. Best Test Sensitivity for frontoparietal, tempero-occipital and Sylvan cistern bleeding events
      2. Susceptibility Weighted Images (SWI)
        1. Best Test Sensitivity for interhemispheric and intraventricular Hemorrhage
      3. T2-Weighted gradient echo
        1. Days 6 to 30 of Headache: 100% Test Sensitivity for SAH
      4. References
        1. Yuan (2005) J Chin Med Assoc 68(3): 131-7 [PubMed]
  6. Magnetic Resonance Angiography
    1. Not routinely recommended as an alternative to CT angiogram in identifying SAH source
    2. Indicated for stable patients in whom iodinated contrast for CTA is contraindicated
    3. Efficacy
      1. Aneurysm 5 mm or larger: 85-100% Test Sensitivity
      2. Aneurysm less than 5mm: 56%

XIII. Management: General

  1. Neurosurgery Consultation (emergent)
    1. Endovascular coiling may be preferred over surgery
      1. Higher one year survival: 23.7% versus 30.6%
      2. Shorter delay to procedure: 1.1 versus 1.7 days
      3. (2002) Lancet 360:1267-74 [PubMed]
  2. Head of Bed at 30 degrees
    1. Indicated in most cases of Intracranial Hemorrhage
    2. Avoid if hypotensive
    3. See Increased Intracranial Pressure below
  3. Consider RSI and intubation
  4. Prevent vasospasm with good hydration
  5. Blood Pressure management
    1. See Hypertension Management for Specific Emergencies
    2. Overall goals (balance two juxtaposed criteria)
      1. Cerebral Perfusion Pressure >60 mmHg
      2. Avoid worsening bleeding into Hemorrhagic CVA
      3. Avoid recurrent Hemorrhage if bleeding has stopped
    3. Normal Intracranial Pressure
      1. Target Systolic Blood Pressure <140 mmHg
      2. Contrast with Spontaneous Intracerebral Hemorrhage, where target is <180 mmHg
        1. Qureshi (2016) N Engl J Med 375(11):1033-43 [PubMed]
    4. Increased Intracranial Pressure (suspected or confirmed)
      1. Systolic Blood Pressure >180 mmHg (or MAP >130 mmHg)
        1. Intermittent Intravenous Antihypertensives (e.g. Labetalol)
        2. Consider continuous antihypertensive infusion (e.g. Nicardipine) - preferred
      2. Systolic Blood Pressure >200 mmHg (MAP<150 mmHg)
        1. Continuous antihypertensive infusion (e.g. Nicardipine)
  6. Seizure Management
    1. Treat Seizures as they occur
    2. Prophylaxis is no longer recommended
    3. Electroencephalogram (EEG) monitoring if Decreased Level of Consciousness
  7. Other measures
    1. Minimize cough with Cough Suppressants
    2. Minimize Pain (Dilaudid, Morphine sulphate)
    3. Minimize Constipation

XIV. Management: Intracranial Pressure

  1. Signs of Increased Intracranial Pressure
    1. Papilledema
    2. Hypertension with Bradycardia (Cushing Reflex)
    3. Contralateral paralysis with dilated pupil (Uncal Herniation)
    4. Head CT with signs of Hemorrhage
  2. Indications for monitoring Intracranial Pressure (pressure catheter)
    1. Glasgow Coma Scale <8
    2. Transtentorial Herniation signs
    3. Significant intraventricular Hemorrhage
    4. Hydrocephalus
  3. Management
    1. Elevate head of bed to 30 degrees (see above)
    2. Target Cerebral Perfusion Pressure 50-70 mmHg
    3. Mannitol
      1. Start at 1 gram/kg and titrate
      2. Check Serum Osmolality (keep 305-315)
      3. Check Serum Sodium every 6 hours (keep >140)
    4. Hypertonic Saline
      1. Previously considered alternative to Mannitol in Increased Intracranial Pressure
      2. Does not improve Intracranial Pressure or benefit mortality in Severe Closed Head Injury
        1. Berger-Pelleiter (2016) CJEM 18(2): 112-20 +PMID:26988719 [PubMed]

XV. Management: Anticoagulant Reversal

  1. See Anticoagulant Reversal
  2. General agents
    1. Tranexamic Acid (not FDA approved)
  3. Warfarin
    1. Prothrombin Complex Concentrate 4 (PCC4) or if not available, Fresh Frozen Plasma (FFP) AND
    2. Vitamin K 10 mg IV
  4. Heparin or Low Molecular Weight Heparin (e.g. Enoxaparin or Lovenox)
    1. Protamine
  5. Factor Xa Inhibitors (e.g. Rivoroxaban or Xarelto, Apixaban or Eliquis) or Direct Thrombin Inhibitors (e.g. Dabigatran)
    1. Factor VII Inhibitor Bypass Activity (FEIBA)
    2. Recombinant activated Clotting Factor VII (rFVIIa or NovoSeven)
    3. Prothrombin Complex Concentrate 4 (PCC4, Kcentra or outside U.S. Octaplex, Beriplex)
  6. Aspirin only
    1. Historical: Transfuse 1 unit (equivalent to 6 pack) of Platelets
      1. Platelet Transfusion associated with worse outcomes (death and worse neurologic function)
      2. Baharoglu (2016) Lancet 387(10038):2605-13 +PMID: 27178479 [PubMed]
  7. ADP Inhibitors (e.g. Clopidogrel)
    1. Historical: Transfuse 2 units (equivalent to 12 pack) of Platelets
      1. Repeat every 12-24 hours for a large Hemorrhage
      2. Platelet Transfusion associated with worse outcomes (see above, under Aspirin)
    2. Desmopressin (DDAVP) 0.3 mcg/kg

XVI. References

  1. Swaminathan and Marcolini in Herbert (2017) EM:Rap 17(6):17-18
  2. Burgess and Stowens (2014) Crit Dec Emerg Med 28(5): 2-13
  3. Levy (2015) Crit Dec Emerg Med 29(4): 10-4
  4. Bederson (2009) Stroke 40(3): 994-1025 [PubMed]
  5. Cohen-Gadol (2013) Am Fam Physician 88(7): 451-6 [PubMed]
  6. van Gijn (2007) Lancet 369(9558): 306-18 [PubMed]

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Related Studies

Ontology: Subarachnoid Hemorrhage (C0038525)

Definition (SNOMEDCT_US) Bleeding into the intracranial subarachnoid space
Definition (SCTSPA) Sangrado en el espacio subaracnoideo intracraneal
Definition (NCI_FDA) Intracranial hemorrhage into the subarachnoid space.
Definition (NCI) Intracranial hemorrhage into the subarachnoid space.
Definition (CSP) hemorrhage within the intracranial or spinal subarachnoid space.
Definition (MSH) Bleeding into the intracranial or spinal SUBARACHNOID SPACE, most resulting from INTRACRANIAL ANEURYSM rupture. It can occur after traumatic injuries (SUBARACHNOID HEMORRHAGE, TRAUMATIC). Clinical features include HEADACHE; NAUSEA; VOMITING, nuchal rigidity, variable neurological deficits and reduced mental status.
Concepts Disease or Syndrome (T047)
MSH D013345
ICD9 430
ICD10 I60 , I60.9
SnomedCT 21454007, 195153006, 195162008, 155390007
English Hemorrhage, Subarachnoid, Hemorrhages, Subarachnoid, Subarachnoid Hemorrhage, Subarachnoid Hemorrhages, SUBARACHNOID HAEMORRHAGE, Subarachnoid haemorrhage NOS, Subarachnoid haemorrhage, unspecified, Subarachnoid hemorrhage, unspecified, Subarachnoid hemorrhage NOS, subarachnoid hemorrhage, subarachnoid hemorrhage (diagnosis), meningeal subarachnoid hemorrhage, meningeal subarachnoid hemorrhage (diagnosis), Hemorrhage subarachnoid, SAH (Subarachnoid Hemorrhage), Subarachnoid Hemorrhage [Disease/Finding], Haemorrhage;subarachnoid, hemorrhage subarachnoid, subarachnoid hemorrhages, SAHs (Subarachnoid Hemorrhage), Subarachnoid bleeding, Subarachnoid intracranial hemorrhage (disorder), Subarachnoid intracranial haemorrhage, Subarachnoid intracranial hemorrhage, Subarachnoid hemorrhage (disorder), Subarachnoid haemorrhage (disorder), Subarachnoid hemorrhage NOS (disorder), Haemorrhage subarachnoid, HEMORRHAGE, SUBARACHNOID, SUBARACHNOID HEMORRHAGE, Subarachnoid hemorrhage, Subarachnoid haemorrhage, SAH - Subarachnoid haemorrhage, SAH - Subarachnoid hemorrhage, hemorrhage; subarachnoid, subarachnoid haemorrhage, Hemorrhage;subarachnoid
French HEMORRAGIE SOUS-ARACHNOIDIENNE, Hémorragie sous-arachoïdienne, Hémorragie sous-arachnoïdienne SAI, Saignement sous-arachnoïdien, Hémorragie sous-arachnoïde, Hémorragie meningée, Hémorragie sous-arachnoïdienne
Spanish HEMORRAGIA SUBARACNOIDEA, Hemorragia subaracnoidea NEOM, Sangrado subaracnoideo, hemorragia subaracnoidea intracraneal (trastorno), hemorragia subaracnoidea intracraneal, hemorragia subaracnoidea (trastorno), hemorragia subaracnoidea, hemorragia subaracnoidea, SAI (trastorno), hemorragia subaracnoidea, SAI, Hemorragia subaracnoidea, Hemorragia Subaracnoidea
Dutch hemorragie subarachnoïdaal, subarachnoïdale bloeding NAO, bloeding; subarachnoïdaal, Subarachnoïdale bloeding, niet gespecificeerd, subarachnoïdale bloeding, Bloeding, subarachnoïdale, Subarachnoïdale bloeding
German subarachnoidale Blutung NNB, BLUTUNG SUBARACHNOIDAL, Subarachnoidalblutung, nicht naeher bezeichnet, Bluten im Subarachnoidalbereich, Subarachnoidalblutung, Blutung, subarachnoidale, Hämorrhagie, subarachnoidale
Italian Emorragia all'interno dello spazio subaracnoideo, Emorragia dello spazio subaracnoideo, Emorragia, subaracnoidea, Emorragia subaracnoidea NAS, Emorragia subaracnoidea SAH, Sanguinamento subaracnoideo, Emorragia subaracnoidea
Portuguese Hemorragia subaracnoideia, Hemorragia subaracnoideia NE, HEMORRAGIA SUBARACNOIDEIA, Hemorragia Subaracnóidea, Sangramento subaracnoideio, Hemorragia subaracnóide
Japanese くも膜下出血NOS, クモマクカシュッケツ, クモマクカシュッケツNOS, 出血-くも膜下, クモ膜下出血, くも膜下出血, 出血-クモ膜下
Swedish Subaraknoidalblödning
Czech subarachnoidální hemoragie, Subarachnoidální krvácení NOS, Krvácení subarachnoidální, Subarachnoidální krvácení, SAK, subarachnoidální krvácení, Subarachnoidální hemoragie
Finnish Lukinkalvonalainen verenvuoto
Korean 거미막밑 출혈, 상세불명의 거미막밑 출혈
Polish Krwotok podpajęczynówkowy
Hungarian Subarachnoidealis haemorrhagia, Subarachnoidealis vérzés k.m.n., Subarachnoideális vérzés, Subarachnoidealis vérzés
Norwegian Subaraknoidalblødning, Hjernehinneblødning