Subarachnoid Hemorrhage (SAH) – quick review

19 Dec

submitted by Christina Brown, M.D.

Definition – Bleeding into the subarachnoid 300px-subarachnoidpspace and CSF:

  • Spontaneous – Most often results from cerebral aneurysm rupture.
  • Traumatic – Represents severe head injury.

 

Epidemiology – Although rare, SAH is a leading cause of pediatric stroke.

 

History

  • Headache is often occipital or nuchal, but may be unilateral.
  • Distinct from prior headaches.
  • Usually develops within seconds and peaks within minutes
  • Maximal at onset.
  • Can be associated w/ seizures, transient loss of consciousness, or altered level of consciousness occur in more than 50% of patients.
  • Vomiting occurs in 70%.
  • High risk features – Syncope, diplopia, and seizure.

 

Physical Exam

  • 33% – Focal neurologic deficits occur at the same time as the headache
  • 10-15% – Third cranial nerve (CN III) palsy (“down and out”)
  • 25%–70% – Nuchal rigidity.
  • Isolated CN VI palsy or papillary dilation may also occur.
  • Retinal hemorrhage may be only clue in comatose patient.

 

Work Up:

  • Emergent noncontrast head CT scan:
    • Diagnoses 93%–98% of SAH if performed within 12 hrs of onset.
    • 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.

Diagnostic Procedures

  • Lumbar puncture:
    • Presence of erythrocytes in CSF indicates SAH or traumatic tap:
      • If traumatic tap suspected, LP should be performed one inter-space higher.
      • Xanthochromia is diagnostic of SAH if performed 12 hours after onset.
    • An elevated opening pressure may indicate SAH, cerebral venous sinus thrombosis, or pseudotumor cerebri.

PRE-HOSPITAL

  • Manage airway, resuscitate as indicated:
    • Rapid sequence intubation

ED TREATMENT/PROCEDURES

  • Manage intracranial pressure (ICP):
    • Elevate head of bed to 30 degrees.
    • Consider pretreatment with lidocaine and defasciculating dose of nondepolarizing paralytic to blunt increase in intracranial pressure (ICP) during intubation.
    • Prevent increases in ICP from vomiting and defecation with antiemetics and stool softeners.
  • Blood pressure (BP) control:
    • Balance HTN-induced rebleeding vs cerebral hypoperfusion
    • Goal systolic BP <160, mean goal between 100-120.
      • Nicardipine, Labetalol
    • Correct hypovolemia:
      • Treat hypotension with volume expansion.
  • Seizure prophylaxis
  • Transfer to facility with neurosurgical capabilities.

 

DISPOSITION

  • All patients with SAH should be admitted to an ICU.
  • Patients with negative CT findings and equivocal LP findings should be admitted.

 

References:

  1. Edlow J A, Malek A M, and Ogilvy C S.: Aneurysmal subarachnoid hemorrhage: Update for emergency physicians. J Emerg Med.2008; 34(3):237–251.
  2. Schaider, J. & Barkin, R. & Hayden, S. & Wolfe, R. & Barkin, A. & Shayne, P. & Rosen, P. (2011). Subarachnoid Hemorrhage. Rosen and Barkin’s 5 minute Emergency Medicine Consult.
  3. Armin S S, Colohan A R, and Zhang J H.: Traumatic subarachnoid hemorrhage: Our current understanding and its evolution over the past half century. Neurol Res.2006; 28(4):445–452.
  4. Bederson J B and ConnollyES Jr. 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. 2009; 40:994–1025.
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