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V. Subarachnoid Hemorrhage and Intracranial Aneurysms

B. Aneurysm Rupture (rupture of a saccular aneurysm is the most common cause of spon­taneous subarachnoid hemorrhage)

1. Incidence: The age group 20-50 is most often affected but a ruptured aneurysm may occur at any age.

2. Clinical course: Rapidly developing severe headache (the "worst headache of my life"), nuchal rigidity (stiff neck),   unconsciousness (consciousness may return soon). CAT scan, arteriography, and bloody CSF on lumbar puncture are helpful in diagnosis. After 3 weeks the CSF becomes xanthochromic due to breakdown of hemoglobin.

3. Prognosis: One-third of patients die of initial rupture, one-third die of a subsequent rupture (recurrence is common within 2 weeks).

4. Complications:

  • Localized arterial vasospasm due to blood and its breakdown products in the subarachnoid space
  • Hydrocephalus from subarachnoid hemorrhage and reactive leptomeningitis

Blood fills the subarachnoid space at the base of the brain. The blood is more dense in the center, surrounding the circle of Willis.
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