title: Defending a traditional practice in the modern era: The use of lumbar puncture in the investigation of subarachnoid haemorrhage.
abstract: BACKGROUND
  Acute severe headache is a common medical presentation, and a common area of diagnostic uncertainty. Subarachnoid haemorrhage (SAH) is the cause in a minority of patients and has a high rate of morbidity and mortality. Therefore, its conclusive diagnosis with computed tomography (CT) or lumbar puncture (LP) is paramount. With advancement in imaging technology, emerging evidence now suggests that LP is no longer required for a subset of patients as CT has 100% sensitivity in detecting SAH, when performed under specific conditions.
  
  
  OBJECTIVE
  To assess the proportion of patients with conclusive CSF xanthochromia results following a negative CT scan in suspected SAH to determine the diagnostic efficacy of LP.
  
  
  METHODS
  CSF bilirubin and oxyhaemoglobin spectrophotometric absorbance data from all centres in a regional health board were identified for consecutive patients over a 6-month period. Results were stratified as conclusive (positive or negative), or inconclusive according to national guidelines.
  
  
  RESULTS
  239 of 255 (93.7%) results were conclusive: 89.0% were negative (227 of 255). 4.7% of results were positive (12 of 255), revealing 4 cerebral aneurysms requiring treatment. 16 out of 255 (6.3%) samples were inconclusive, yielding 1 aneurysm requiring treatment. In the same period, there were 27 CT-positive cases of SAH.
  
  
  CONCLUSIONS
  LP has a high diagnostic yield, eliminating the need for neurosurgical opinion or investigation in almost 90% of cases. The test is both cost and time efficient and subjects only a small number of patients to the radiation and contrast risks of angiography.
authors.affiliation: a Department of Acute Medicine , Wishaw General Hospital , Wishaw , UK.|b Department of Neurosurgery , Institute of Neurological Science , Glasgow , UK.|d Emergency Department, John Radcliffe Hospital , Oxford , UK.
authors.forename: Sean C G
authors.initials: SC
authors.lastname: Martin
authors.affiliation: b Department of Neurosurgery , Institute of Neurological Science , Glasgow , UK.
authors.forename: Mario K C H
authors.initials: MK
authors.lastname: Teo
authors.affiliation: b Department of Neurosurgery , Institute of Neurological Science , Glasgow , UK.
authors.forename: Adam M H
authors.initials: AM
authors.lastname: Young
authors.affiliation: c Department of Clinical Biochemistry , Monklands Hospital , Airdrie , UK.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Godber
authors.affiliation: d Emergency Department, John Radcliffe Hospital , Oxford , UK.
authors.forename: Sachin S
authors.initials: SS
authors.lastname: Mandalia
authors.affiliation: b Department of Neurosurgery , Institute of Neurological Science , Glasgow , UK.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: St George
authors.affiliation: a Department of Acute Medicine , Wishaw General Hospital , Wishaw , UK.
authors.forename: Calum
authors.initials: C
authors.lastname: McGregor
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001663:Bilirubin / Q000134:cerebrospinal fluid; D002648:Child; D002675:Child, Preschool; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D019635:Neurosurgical Procedures / Q000706:statistics & numerical data; D010108:Oxyhemoglobins / Q000134:cerebrospinal fluid; D015203:Reproducibility of Results; D013129:Spinal Puncture / Q000191:economics / Q000379:methods*; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis* / Q000401:mortality; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D010108:Oxyhemoglobins; D001663:Bilirubin
keywords: CT scan; aneurysm; cerebral angiography; spinal puncture; subarachnoid haemorrhage