Diagnosis
How is the diagnosis made? Clinical + CT head. If normal CT, do LP to look for Xanthochromia. The absence of Xanthochromia r/o subarachnoid hemorrhage.
–Headache Red Flags.
“Early diagnosis of a nontraumatic subarachnoid hemorrhage is paramount for achieving a good outcome when a patient presents with a headache that is unusually severe and feels different than other headaches.
Risk factors include smoking, hypertension, heavy alcohol use, and a family history of aneurysm or hemorrhagic stroke. The initial evaluation should consist of noncontrast CT of the head (SOR C). If it is negative or equivocal the next step would be to perform a lumbar puncture to determine whether or not the cerebrospinal fluid is xanthochromic. The absence of xanthochromia rules out subarachnoid hemorrhage (SOR C).” ABFM
Reference
Am Fam Physician 2013;88(7):451-456. http://www.aafp.org/afp/2013/1001/p451.html
JAMA 2013;310(12):1248-1255. Clinical Decision Rules to Rule Out Subarachnoid Hemorrhage for Acute Headache. http://jamanetwork.com/journals/jama/fullarticle/1741823