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Subarachnoid Hemorrhage, Emergency Medicine

Basics

Description

- 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

- 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

- 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

- ECG: - ST-segment elevation or depression - QT prolongation - T-wave abnormalities - Often mimics ischemia or infarction - Symptomatic bradycardia, ventricular tachycardia, and ventricular fibrillation

- Initial assessment and history: - Level of consciousness - Glasgow Coma Scale score - Gross motor deficits - Other focal deficits

- 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

- 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

  • Bleeding into the subarachnoid space and CSF:Spontaneous:Most often results from cerebral aneurysm ruptureAneurysms 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 arteriesIncidence 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 endocarditisArteriovenous malformationsVertebral or carotid artery dissectionIntracranial neoplasmPituitary 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 minutesDistinct from prior headachesHeadache 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 hrThin 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 planningQuite sensitive for detection of aneurysms >4 mm, less with smaller aneurysms
  • MR angiography:MRI is less sensitive for hemorrhageQuite 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 depressionQT prolongationT-wave abnormalitiesOften mimics ischemia or infarctionSymptomatic 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 consciousnessGlasgow Coma Scale scoreGross motor deficitsOther 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 intubationPretreat with lidocaine and defasciculating dose of nondepolarizing paralytic to blunt increase in intracranial pressure (ICP) during intubation.Cardiac monitoring and pulse oximetryEstablish 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 hypoperfusionGoal mean arterial pressure 100 " 120 mm Hg, systolic BP <160:Labetalol, hydralazine, nitroprusside, or nicardipine for hypertensionCorrect hypovolemia:Should start within 96 hr of SAHTreat hypotension with volume expansion.
  • Cerebral vasospasm:May cause secondary ischemia and infarction after SAH:Oral nimodipine improves functional outcome:Discuss with neurosurgeon prior to administrationMonitor with transcranial Doppler.
  • Adequately treat pain.
  • Seizures:Manage with IV benzodiazepineConsider 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 initiationConsider 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)