Basics
Description
- Bleeding into the subarachnoid space and CSF:
- Spontaneous:
- Most often results from cerebral aneurysm rupture
- Aneurysms that occur are more likely to rupture (>25 mm).
- Traumatic:
- Represents severe head injury
Epidemiology
- Incidence is 6 " 16 per 100,000 individuals.
- Affects 21,000 in US annually
- Associated mortality in 30 " 50% of patients
- Uncommon prior to 3rd decade; incidence peaks in 6th decade
Risk Factors
- Previous ruptured aneurysm who have other aneurysms
- Family history
- Hypertension
- Smoking
- Alcohol abuse
- Sympathomimetic drugs:
- Cocaine, methamphetamine, and ecstasy (MDMA) use
- Gender (female:male 1.6:1)
Genetics
- 3 " 7-fold increased risk with 1st-degree relatives with subarachnoid hemorrhage (SAH)
- Strongest genetic association represents only 2% of SAH patients:
- Autosomal dominant polycystic kidney disease, Ehlers " Danlos type IV, familial intracranial aneurysms
- Most often due to arteriovenous malformation in children
- Although rare in children, SAH is a leading cause of pediatric stroke.
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
Diagnosis
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.
- 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:
- 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
- Arterial 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
Treatment
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:
- Labetalol, hydralazine, nitroprusside, or nicardipine for hypertension
- 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 Όg/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 Όg/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/Other Procedures
- Per neurosurgical consultant
- Early operative or endovascular intervention may prevent vasospasm and improve outcome.
Follow-Up
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.
Pearls and Pitfalls
- Failure to consider SAH in differential diagnosis for new, acute headache
- Failure to assess previous headache workup as complete (CT and LP)
Additional Reading
- Bederson JB, Connolly ES Jr, Batjer HH, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: A statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke. 2009;40:994 " 1025.
- Edlow JA, Malek AM, Ogilvy CS. Aneurysmal subarachnoid hemorrhage: Update for emergency physicians. J Emerg Med. 2008;34(3):237 " 251.
- Rabinstein AA. The AHA Guidelines for the Management of SAH: What we know and so much we need to learn. Neurocrit Care. 2009;10(3):414 " 417.
- Uysal E, Yanbulo lu B, Ert Όrk M, et al. Spiral CT angiography in diagnosis of cerebral aneurysms of cases with acute subarachnoid hemorrhage. Diagn Interv Radiol. 2005;11(2):77 " 82.
- Wolfson A. Blunt neck trauma. In: Wolfson AB, Hendey GW, Hendry PL, et al., eds. Harwood-Nuss ' Clinical Practice of Emergency Medicine. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.
Codes
ICD9
- 430 Subarachnoid hemorrhage
- 852.00 Subarachnoid hemorrhage following injury without mention of open intracranial wound, unspecified state of consciousness
ICD10
- I60.9 Nontraumatic subarachnoid hemorrhage, unspecified
- S06.6X0A Traum subrac hem w/o loss of consciousness, init
SNOMED
- 21454007 Subarachnoid intracranial hemorrhage (disorder)
- 262955000 Traumatic intracranial subarachnoid hemorrhage (disorder)
- 270907008 Spontaneous subarachnoid hemorrhage
- 230719004 intracranial subarachnoid hemorrhage due to ruptured aneurysm (disorder)