title: Risk-benefit analysis of lumbar puncture to evaluate for nontraumatic subarachnoid hemorrhage in adult ED patients.
abstract: OBJECTIVE
  The objective of the study is to compare the risks and benefits of lumbar puncture (LP) to evaluate for subarachnoid hemorrhage (SAH) after a normal head computed tomographic (CT) scan.
  
  
  METHODS
  This was an observational study of adult emergency department patients at a single hospital who presented with headache and underwent LP after a normal head CT to evaluate for SAH. Lumbar puncture results classified as indicating a SAH included xanthochromia in cerebrospinal fluid (CSF) or red blood cells in the final tube of CSF with an aneurysm or arteriovenous malformation on cerebral angiography. An LP-related complication was defined as hospitalization or a return visit due to symptoms attributed to the LP. Proportions of the study patients who had SAH diagnosed by LP and who experienced an LP-related complication were compared.
  
  
  RESULTS
  The study included 302 patients, including 2 (0.66%) who were diagnosed with SAH based on LP (number needed to diagnose, 151); both of these patients had a known intracranial aneurysm. Eighteen (5.96%) patients experienced an LP-related complication (P < .01 compared with number with SAH diagnosed; number needed to harm, 17). Complications included 12 patients with low-pressure headaches, 4 with pain at the LP site, and 2 with contaminated CSF cultures.
  
  
  CONCLUSIONS
  The yield of LP for diagnosing SAH in adults with nontraumatic headache after a normal head CT was very low. The severity of LP-related complications was low, but complications were more common than SAH diagnoses. Lumbar puncture may not be advisable after a normal head CT to evaluate for SAH, particularly in patients with low-risk clinical features for SAH.
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Migdal
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: W Kelly
authors.initials: WK
authors.lastname: Wu
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Drew
authors.initials: D
authors.lastname: Long
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Candace D
authors.initials: CD
authors.lastname: McNaughton
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ward
authors.affiliation: Vanderbilt University School of Medicine, Nashville, TN, USA. Electronic address: wesley.self@vanderbilt.edu.
authors.forename: Wesley H
authors.initials: WH
authors.lastname: Self
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004636:Emergency Service, Hospital; D005260:Female; D006261:Headache / Q000209:etiology*; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D013129:Spinal Puncture / Q000009:adverse effects*; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed; D055815:Young Adult