How is Subarachnoid Hemorrhage diagnosed?
SAH due to aneurysm rupture classically presents with the worst headache of one’s life; loss of consciousness, nausea/vomiting, nuchal rigidity, and focal neurologic signs are also common.
Although large amounts of subarachnoid blood are readily apparent on CT, even small amounts of subarachnoid blood can provoke symptoms. Detection of these small “sentinel bleeds” are vital, as they herald aneurysm rupture.
Sensitivity of CT declines with time from symptom onset, so spinal fluid should be examined for red blood cells or xanthochromia if head CT is negative and clinical suspicion high.
Because of its ready availability, CT angiogram is often performed acutely in lieu of conventional angiogram for surgical planning.