Author:
Thien H.Nguyen
Binh T.Ly
Description
- Bleeding into the subarachnoid space and CSF:
- Spontaneous:
- Results from ruptured cerebral artery aneurysm in up to 80% of cases
- Aneurysms that are >25 mm are more likely to rupture
- Traumatic:
Epidemiology
- Incidence is 6-16 per 100,000 individuals
- Affects 21,000 in the U.S. annually
- Associated mortality in 30-50% of patients with 1 in 4 dying within 1 d
- Uncommon prior to third decade of life; incidence peaks in sixth decade
Risk Factors
- Aneurysms ≥7 mm have greater risk for rupture
- After adjustment for size and location, aneurysm aspect ratio >1.3 and irregular shape also significantly associated with rupture
- Family history
- Hypertension
- Smoking
- Alcohol abuse
- Sympathomimetic drugs:
- Cocaine, methamphetamine, and ecstasy (MDMA)
- Gender (female:male 1.6:1)
Genetics
- Three- to sevenfold increased risk in first-degree relatives with subarachnoid hemorrhage (SAH)
- Strongest genetic association represents only 2% of SAH patients:
Pediatric Considerations |
- Most often due to arteriovenous malformation in children
- Although rare in children, SAH is a leading cause of pediatric stroke
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Etiology
- “Congenital,” saccular, or berry aneurysm rupture (80-90%):
- Occur at bifurcations of major arteries
- Incidence increases with age
- Aneurysms may be multiple in 20-30%
- Nonaneurysmal perimesencephalic hemorrhage (10%)
- Remaining 5% of causes include:
- Mycotic (septic) aneurysm due to syphilis or endocarditis
- Arteriovenous malformations
- Vertebral or carotid artery dissection
- Intracranial neoplasm
- Pituitary apoplexy
- Severe closed head injury
Signs and Symptoms
History
- Classically a severe, sudden headache:
- Often described as “thunderclap” or “worst headache of life.” Usually develops within seconds and peaks within minutes
- Headache often maximal at onset
- Distinct from prior headaches
- Headache is often occipital or nuchal but may be unilateral
- During micturition, defecation, or other Valsalva maneuver
- During sexual activity including masturbation
- Sentinel headaches and minor bleeding occur in 20-50%:
- May occur days to weeks prior to presentation and diagnosis
- Seizures, transient loss of consciousness, or altered level of consciousness occur in >50% of patients
- Vomiting occurs in 70%
- Syncope, diplopia, and seizure are particularly high-risk features for SAH
Physical Exam
- Focal neurologic deficits occur at the same time as the headache in 33% of patients:
- Third cranial nerve (CN III) palsy (the “down and out” eye) occurs in 10-15%
- Isolated CN VI palsy or papillary dilation may also occur
- Nuchal rigidity develops in 25-70%, and is the most accurate finding on history or exam with a positive likelihood ratio [LR+] 4.12, 95% CI 2.24-7.59
- Retinal hemorrhage may be the only clue in comatose patient
Essential Workup
- Complete neurologic exam
- Fundoscopic exam may be helpful
- Emergent noncontrast head CT scan:
- If performed within 6 hr of headache onset has sensitivity of 97.0-100.0% and specificity of 99.5-100.0%
- Beyond 6 hr CT is still accurate to rule-in SAH but should not be used to rule-out SAH
- Thin cuts (3 mm) through base of brain improve diagnostic yield
- CT is less sensitive after 24 hr or if hemoglobin <10 g/L
- Before performing LP, consider risks and benefits:
- The number needed to LP (NNLP) to identify one additional aneurysmal SAH, which was missed by CT within 6 hr and requires neurosurgical intervention, ranges from 250 to 15,200
- Shared decision-making is advised
Pregnancy Prophylaxis |
- Incidence slightly increased in pregnancy
- Workup should include MRI (preferred) or CT and LP
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Diagnostic Tests & Interpretation
Lab
- Baseline CBC
- Electrolytes, renal function tests
- Coagulation studies
- Cardiac markers:
- Troponin I elevated in 10-40%
- CSF analysis (see below)
Imaging
- CXR for pulmonary edema:
- Occurs in up to 40% with severe neurologic deficit
- Spiral CT angiography:
- Useful for operative planning
- Quite sensitive for detection of aneurysms >4 mm, less with smaller aneurysms
- MR angiography:
- MRI is less sensitive for hemorrhage
- Very sensitive for detection of aneurysms >4 mm, less with smaller aneurysms
- Transcranial Doppler ultrasound:
- May be useful in detecting vasospasm
Diagnostic Procedures/Surgery
- LP:
- Presence of erythrocytes in CSF indicates SAH or traumatic tap:
- Recent literature suggests that patients with SAH are unlikely to have RBCs <100 in the final tube; alternatively RBCs >10,000 in the final tube increased the odds of SAH by a factor of 6
- If traumatic tap suspected, LP should be performed 1 interspace higher
- Diminishing erythrocyte count in successive tubes suggests but does not firmly establish a traumatic tap
- Xanthochromia can be used to rule-in SAH but is less accurate to rule it out
- An elevated opening pressure may indicate SAH, cerebral venous sinus thrombosis, or pseudotumor cerebri
- ECG:
- Q and QS abnormalities
- ST-segment elevation or depression
- QT prolongation
- T-wave abnormalities
- Often mimics ischemia or infarction
- Symptomatic bradycardia, ventricular tachycardia, and ventricular fibrillation
Differential Diagnosis
- Neoplasm
- Carotid or vertebral dissection
- Aneurysm (unruptured)
- Arteriovenous malformation
- Migraine
- Pseudotumor cerebri
- Meningitis
- Encephalitis
- Hypertensive encephalopathy
- Hyperglycemia or hypoglycemia
- Temporal arteritis
- Acute glaucoma
- Subdural hematoma
- Epidural hematoma
- Intracerebral hemorrhage
- Thromboembolic stroke
- Sinusitis
- Seizure disorder
- Cerebral venous sinus thrombosis
- Cavernous sinus thrombosis
- Carbon monoxide poisoning
Prehospital
- Initial assessment and history:
- Level of consciousness
- Mental status
- Glasgow coma score
- Gross motor deficits
- Other focal deficits
- Patients with SAH may need emergent intubation for rapidly deteriorating level of consciousness
- IV access should be established
- Monitor cardiac rhythm
- Patients should be transported to a hospital with emergent CT and ICU capability
Initial Stabilization/Therapy
- Manage airway, resuscitate as indicated:
- Rapid-sequence intubation (RSI)
- If using succinylcholine, consider a defasciculating dose of nondepolarizing paralytic to blunt increase in intracranial pressure (ICP) during intubation
- Consider RSI pretreatment with lidocaine and fentanyl for neuroprotection
- Cardiac pulse oximetry and end-tidal CO2 monitoring
- Obtain urgent neurosurgical consultation
ED Treatment/Procedures
- Prevent rebleeding:
- Risk of rebleeding highest in the first few hours after aneurysmal rupture
- ICP management:
- Elevate head of bed to 30°
- Prevent increases in ICP from vomiting and defecation with antiemetics and stool softeners
- Controlled ventilation to goal pCO2 = 30
- Meta-analyses suggest that boluses of hypertonic saline may have greater efficacy than mannitol; however, long-term clinical outcomes remain unclear
- Maintain urine output >50 mL/hr
- BP control:
- Balance HTN-induced rebleeding vs. cerebral hypoperfusion
- Goal mean arterial pressure 70-110 mm Hg, systolic BP <160:
- Correct hypovolemia:
- Treat hypotension with volume expansion
- Cerebral vasospasm:
- May cause secondary ischemia and infarction after SAH:
- Oral nimodipine improves functional outcome:
- Discuss with neurosurgeon prior to administration
- Consider monitoring with transcranial Doppler
- Adequately treat pain
- Seizures:
- Manage with IV benzodiazepine
- Consider prophylactic anticonvulsants in immediate posthemorrhagic period
- Correct temperature, electrolyte, glucose, or pH abnormalities
- Treat coagulopathy, thrombocytopenia, and severe anemia
- Monitor for cardiac dysrhythmias and treat noncardiogenic pulmonary edema
- Antifibrinolytic therapies:
- Discuss with neurosurgeon prior to initiation
- Consider administration immediately after aneurysmal rupture in patients at high risk of rebleeding when this is combined with treatment of aneurysm and monitoring for hypotension
- When patient is stable, expedited transfer to hospital with neurosurgical capabilities is mand atory
Medication
Anticonvulsants:
- Diazepam: 5-10 mg (peds: 0.2-0.3 mg/kg) IV, may repeat once in 5 min
- Fosphenytoin/phenytoin: 15-20 mg/kg IV × 1
- Lorazepam: 2-4 mg (peds: 0.03-0.05 mg/kg/dose; max 4 mg/dose) IV q15min p.r.n
- Midazolam: 1-2 mg (peds: 0.15 mg/kg IV × 1) IV/IM q10min p.r.n
- Morphine: 2-10 mg (peds: 0.05-0.2 mg/kg IV) q2-4h p.r.n
Antiemetics:
- Ondansetron: 4-8 mg (peds: 0.1-0.15 mg/kg max 4 mg) IV/IM/PO q4-6h p.r.n
- Metoclopramide: 5-10 mg (peds 1 mg/kg) IV/IM q8h p.r.n
- Prochlorperazine: 5-10 mg (peds: >2 yr and >9 kg: 0.1 to 0.15 mg/kg/dose) IV/IM q3-4h p.r.n
- Promethazine: 12.5-25 mg (peds >2 yr old: 0.25-1 mg/kg; max 25 mg/dose) IV/IM q4-6h p.r.n
Antihypertensives:
- Hydralazine: 10-20 mg (peds: 0.1-0.5 mg/kg IV) q30min-4h p.r.n
- Labetalol: 20 mg IV bolus, then 40-80 mg q10min; max 300 mg; follow with IV continuous infusion 0.5-2 mg/min (peds: 0.2-1 mg/kg IV q10min p.r.n, 0.4-1 mg/kg/hr IV continuous infusion; max 3 mg/kg/hr)
- Lidocaine: 1-1.5 mg/kg IV × 1 (adults and peds)
- Nicardipine: 5-15 mg/hr IV continuous infusion (peds: Safety not established)
- Nimodipine: 60 mg PO/gastric tube q4h; (peds: Safety not established)
- Nitroprusside: 0.25-10 mcg/kg/min IV continuous infusion (adults and peds)
ICP control:
- Fentanyl: 2-5 mcg/kg to blunt ICP during RSI; 1-3 mcg/kg IV q1-4h p.r.n
- Hypertonic saline: 250 mL 3% (513 mEq/L) or 30 mL 23.4% (4,000 mEq/L) by central line over 20 min (peds 2 mL/kg 3%); goal serum Na 145-150 mEq/L; avoid overcorrecting serum Na >12 mEq/24 hr to avoid osmotic demyelination
- Mannitol: IV: 0.25-1 g/kg/dose; may repeat q6-8h p.r.n, goal 300-320 mOsm/kg (same dose for peds)
Surgery/Other Procedures
- Per neurosurgical consultant, specifically aneurysm coiling or clipping if applicable
- Early operative or endovascular intervention may prevent vasospasm and improve outcome
Disposition
Admission Criteria
- All patients with SAH should be admitted to an ICU
- Consider consulting neurosurgery or observation admission for patients with negative CT findings and equivocal LP findings
Discharge Criteria
- Patients with negative CT and LP findings and onset of symptoms <2 wk
- Outpatient follow-up for headache treatment and further evaluation
Issues for Referral
Early referral to center with access to neurosurgeons and endovascular specialists
Prognosis
- Mortality is 12% before arrival to hospital
- Ultimately fatal in >50%
- In cases of “sentinel bleed” or early detection of aneurysmal rupture, outcomes are improved with early surgical or interventional approaches