“Doctor, this is the worst headache of my life!” moans the 33 year old mother of three on a blustery winter evening. She reports that the “stabbing” left-sided frontal headache began at 4:03PM while driving her daughter to tennis practice. The headache is unremitting over the subsequent two-hours and she notes associated nausea. She denies any prior history of headache disorders (no migraines or tension headaches) and cannot remember any recent or remote head trauma. She takes birth control pills, but denies any other daily medication use. She denies any recent travel history or sick contacts. She has no family history of aneurysms. On review of symptoms, she denies any other symptoms, including no fever, cough, or sore throat. On physical exam you note an extremely uncomfortable and tearful adult without any obvious trauma. Her vital signs are unremarkable and a detailed neurological exam demonstrates no focal deficits.With this presentation, you are highly suspicious for subarachnoid hemorrhage. A Bayesian diagnostician, you develop the following list of diagnostic possibilities (with your gestalt-based pre-test probabilities): new-onset migraine (50%), tension headache (25%), subarachnoid hemorrhage (15%), cerebral venous sinus thrombosis (5%), CNS infection (3%), non-CNS infection (2%). In discussing these possibilities with your patient and her husband, you mention that a lumbar puncture will be essential to definitively exclude subarachnoid hemorrhage, even if a head CT is non-diagnostic/normal. Since she is not a big fan of long needles in her back, your patient tells you that she will not consent to a lumbar puncture for any reason. As you order an intravenous anti-emetic to provide her symptom relief from her headache and nausea, you contemplate on the diagnostic accuracy for subarachnoid hemorrhage of CT alone.
Search Strategy: Using the PUBMED Clinical Queries diagnosis/broad filter you conduct a search for “subarchnoid hemorrhage” yielding 7121 citations which you then combine with a search for “computed tomography” yielding 2305 citations. Because you are most interested in the newest generation CT scanners, you add limits for English-only and published in the last 5-years to yield 535 citations (see http://tinyurl.com/7wmbend) which contains all of the manuscripts below.
Population: ED headache patients with suspected subarachnoid hemorrhage
Intervention: Cranial CT alone
Comparison: Cranial CT + lumbar puncture
Outcome: Diagnostic accuracy, procedural morbidity
Second years: Is the combination of negative computed tomography result and negative lumbar puncture result sufficient to rule out subarachnoid hemorrhage? Ann Emerg Med 2008; 51: 707-713. (http://pmid.us/18191293)Fourth years: Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study, BMJ 2011; 343: d4277. (http://pmid.us/21768192)
Article 1 Answer Key - PGY-I: Answer Key - Determining the sensitivity of computed tomography scanning in early detection of subarachnoid hemorrhage, Neurosurgery 2010; 66: 900-903. (http://pmid.us/20404693)
Article 2 Answer Key - PGY-II: Answer Key - Is the combination of negative computed tomography result and negative lumbar puncture result sufficient to rule out subarachnoid hemorrhage? Ann Emerg Med 2008; 51: 707-713. (http://pmid.us/18191293)
Article 3 Answer Key - PGY-III: Answer Key - Sensitivity of noncontrast cranial computed tomography for the emergency department diagnosis of subarachnoid hemorrhage, Ann Emerg Med 2008; 51: 697-703. (http://pmid.us/18207607)Article 4 Answer Key - PGY IV: Answer Key - Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study, BMJ 2011; 343: d4277. (http://pmid.us/21768192)