Subarachnoid Hemorrhage

Summary

Subarachnoid hemorrhages describe bleeding under the arachnoid layer of the meninges surrounding the brain. These most often occur due to rupture of a saccular, or berry, aneurysms. Subarachnoid hemorrhage clinically presents with a sudden severe headache, known as an acute thunderclap headache. The bleeding into the subarachnoid space can also cause meningeal irritation, leading to nuchal rigidity and photophobia. One serious complication of subarachnoid hemorrhages is vasospasm, in which constriction of cerebral arteries occur several days after the bleed to cause ischemia and stroke. To prevent vasospasm after a subarachnoid hemorrhage, patients are often treated with nimodipine. Hydrocephalus is another possible complication of subarachnoid hemorrhages, due to blood clotting in the passages normally reserved for CSF. Finally, subarachnoid hemorrhages can be diagnosed with a lumbar puncture, which reveals a xanthochromic CSF, with a red-yellow color due to the presence of blood.

Key Points

• Subarachnoid Hemorrhage
  • Cause
    • Bleeding (hemorrhage) due to arterial rupture in subarachnoid space
      • Usually due to rupture of an saccular (berry) aneurysm
        • Contrast vs. Charcot-Bouchard microaneurysm, which typically causes intraparenchymal hemorrhage
  • Presentation
    • Acute thunderclap headache
      • Usually described as sudden onset of “worst headache of my life”
    • Signs of meningeal irritation
      • Nuchal rigidity (stiff neck)
      • Photophobia, phonophobia
  • Complications
    • Vasospasm or rebleed 3-10 days later
    • Communicating and/or obstructive hydrocephalus
      • Due to blood accumulation and clotting in CSF
  • Diagnosis
    • CT Head without Contrast
    • Lumbar Puncture (LP)
      • Always rule out acute bleed before conducting LP
      • Bloody or yellow (xanthochromic) CSF retrieved
    • Angiogram
  • Treatment
    • Give nimodipine to prevent vasospasm
    • Surgical clipping or endovascular coiling (angiogram)