SIGNS AND SYMPTOMS 
History
- Classically a severe, sudden headache:
- Often described as "thunderclap" or "worst headache of life"
- Headache is often occipital or nuchal, but may be unilateral.
- Usually develops within seconds and peaks within minutes
- Distinct from prior headaches
- Headache often maximal at onset
- 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 more than 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:
- 3rd 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%.
- Retinal hemorrhage may be the only clue in comatose patient.
ESSENTIAL WORKUP
- Complete neurologic exam and fundoscopic exam
- Emergent noncontrast head CT scan:
- Diagnoses 93–98% of SAH if performed within 12 hr
- Thin cuts (3 mm) through base of brain improve diagnostic yield.
- CT is less sensitive after 24 hr or if hemoglobin < 10 g/L.
- Lumbar puncture (LP) and CSF analysis must be performed if CT negative and history suggests possibility of SAH.
Pregnancy Considerations
- Incidence slightly increased in pregnancy
- Workup should include CT and LP
DIAGNOSIS TESTS & INTERPRETATION
Lab
- Baseline CBC and differential
- Electrolytes, renal function tests
- Coagulation studies
- Cardiac markers:
- Troponin I elevated in 10–40%
- CSF analysis (see below)
Imaging
- Chest radiograph for pulmonary edema:
- Occurs in up to 40% with severe neurologic deficit
- Traditional gold standard: 4-vessel digital subtraction cerebral angiography
- 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
- Quite 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:
- 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 is diagnostic of SAH if performed 12 hr after onset.
- An elevated opening pressure may indicate SAH, cerebral venous sinus thrombosis, or pseudotumor cerebri.
- ECG:
DIFFERENTIAL DIAGNOSIS
[Outline]
PRE-HOSPITAL
- Initial assessment and history:
- Level of consciousness
- Glasgow Coma Scale 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.
- Provide supplemental oxygen.
- 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
- Pretreat with lidocaine and defasciculating dose of nondepolarizing paralytic to blunt increase in intracranial pressure (ICP) during intubation.
- Cardiac monitoring and pulse oximetry
- Establish adequate IV access
- Obtain urgent neurosurgical consultation
ED TREATMENT/PROCEDURES
- Prevent rebleeding:
- Risk of rebleeding highest in the 1st few hours after aneurysmal rupture
- Manage ICP:
- Elevate head of bed to 30°.
- Prevent increases in ICP from vomiting and defecation with antiemetics and stool softeners.
- Treat increased ICP with controlled ventilation and mannitol.
- Maintain central venous pressure > 8 mm Hg and urine output > 50 mL/hr
- BP control:
- Balance HTN-induced rebleeding vs. cerebral hypoperfusion
- Goal mean arterial pressure 100–120 mm Hg, systolic BP < 160:
- Correct hypovolemia:
- Should start within 96 hr of SAH
- 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
- Monitor 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 and correct pulmonary edema and cardiac arrhythmias.
- 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 mandatory.
MEDICATION
- Diazepam: 5–10 mg (peds: 0.2–0.3 mg/kg) IV/IM q10–1min PRN; max. 30 mg (peds: 10 mg)
- Fentanyl: 1–3 µg/kg (adults and peds) IV q1–4h PRN
- Fosphenytoin: 15–20 phenytoin equivalents (PE) per kg (adults and peds) IV × 1; maintenance 4–6 mg/kg/d IV
- Hydralazine: 10–20 mg (peds: 0.1–0.5 mg/kg IV) q30min–4h PRN
- Labetalol: 20 mg IV bolus, then 40–80 mg q10min; max. 300 mg; follow with IV continuous infusion 0.5–2 mg/min (peds: 0.4–1 mg/kg/h IV continuous infusion; max. 3 mg/kg/h)
- Lidocaine: 1–1.5 mg/kg IV × 1 (adults and peds)
- Lorazepam: 2–4 mg (peds: 0.03–0.05 mg/kg/dose; max. 4 mg/dose) IV q15min PRN
- Midazolam: 1–2 mg (peds: 0.15 mg/kg IV × 1) IV q10min PRN
- Morphine: 2–10 mg (peds: 0.05–0.2 mg/kg IV) q2–4h PRN
- Nicardipine: 5–15 mg/h IV continuous infusion (peds: Safety not established)
- Nimodipine: 60 mg PO/NGT q4h; (peds: Safety not established)
- Nitroprusside: 0.25–10 µg/kg/min IV continuous infusion (adults and peds)
- Ondansetron: 4–8 mg (peds: 0.1–0.15 mg/kg max. 4 mg) PO/IM/IV TID PRN
- Phenytoin: 15–20 mg/kg IV load at max. 50 mg/min; max. 1.5 g; maintenance 4–6 mg/kg/d IV; (adult and pediatric)
- Promethazine: 12.5–25 mg (peds > 2 yr old: 0.25–1 mg/kg; max. 25 mg/dose) PO/IM/IV q4–6h PRN
SURGERY
- Per neurosurgical consultant
- Early operative or endovascular intervention may prevent vasospasm and improve outcome.
[Outline]
DISPOSITION
Admission Criteria
- All patients with SAH should be admitted to an ICU.
- Patients with negative CT findings and equivocal LP findings should be admitted for observation.
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 (if none at practicing institution)
PROGNOSIS
- Mortality is 12% before arrival to hospital.
- Ultimately fatal in more than 50%.
- In cases of "sentinel bleed" or early detection of aneurysmal rupture, outcomes are improved with early surgical or interventional approaches.
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