My Synopsis of AFP's "Recognition and Evaluation of Nontraumatic Subarachnoid Hemorrhage and Ruptured Cerebral Aneurysm"

Recognition and Evaluation of Nontraumatic Subarachnoid Hemorrhage and Ruptured Cerebral Aneurysm
AARON A. COHEN-GADOL, MD, MSc, and BRADLEY N. BOHNSTEDT, MD, Indiana University School of Medicine, Indianapolis, Indiana
Am Fam Physician. 2013 Oct 1;88(7):451-456.
http://www.aafp.org/afp/2013/1001/p451.pdf

     Nontraumatic subarachnoid hemorrhage is due to a ruptured aneurysm in the brain. If the clinician suspects an SAH, then the patient should be sent to the ER.  Most of the time the symptoms are generic and nonspecific. These kinds of patients are likely to be misdiagnosed. Common obvious symptoms include a thunderclap headache or the "worst headache on my life".  Patients may state that the headache feels "different" than ones previously experienced. Other less common symptoms include back pain, meningismus, dysphagia, lightheadedness, dizziness, nausea, weakness, or focal neurologic deficits. Patients with autosomal dominant polycystic kidney disease have an increased risk of SAH. Questions that you can ask to qualify the patient include asking about headache severity, headache onset, previous history of aneurysm or SAH, significant family history, smoking history, alcohol and illicit drug history, and history of hypertension.
     All patients with a suspected SAH should reflexively get a noncontrast CT head. The most common reason for misdiagnosis is not getting a CT. It is 85% sensitive if done within 5 days, but 50% sensitive if done after a week. It may also be hard to identify on CT if the patient has a hemoglobin below 10 g/dL. Negative CT results will trigger an LP. A positive LP will show xanthochromia (blood breakdown causing a yellow discoloration). If the LP or CT was positive, then the patient will be sent for a CT angiogram. If it is negative then it will be repeated in a week. If it is positive then the neurosurgeon can decide on the course of action.
     MRI and fluid-attenuated inversion recovery (FLAIR) are other image studies that can be considered, especially of the patient cannot tolerate contrast.