Subarachnoid Hemorrhage

Suspect a SAH “warning leak” in any patient with an acute headache and both of the following parameters:

  • New onset of the “worst headache ever;”  AND
  • Sudden Onset: Pain reaches maximal intensity immediately, within 1-2 minutes.   Called “thunderclap.”

A non-contrast head CT is 100% sensitive within the first 12 hours, over 90% within the first 24 hours, but only 60% at one week, as blood is resorbed.  Similarly, a lumbar puncture is highly sensitive throughout the first week, much less so after two.  If you entertain the diagnosis at all, don’t delay.

Most commonly due to a ruptured cerebral aneurysm, though also AVMs, cocaine/amphetamine use, or even sympathomimetics in appetite suppressants / cold remedies (especially for women).  Aneurysm incidence is <1 of 4,000, but very common in polycystic kidney disease; also suspect if a positive family history.

See posting Acute Headache – 1.