title: Appreciation of CT-negative, lumbar puncture-positive subarachnoid haemorrhage: risk factors for presence of aneurysms and diagnostic yield of imaging.
abstract: OBJECTIVE
  Patients without a subarachnoid haemorrhage (SAH) on brain CT scan (CT-negative), but a lumbar puncture (LP)-proven SAH, are a challenging patient category. The optimal diagnostic approach is still a matter of debate. Also, there is little knowledge on the probability of finding an underlying vascular lesion.
  
  
  METHODS
  In this observational study, a consecutive cohort of 94 patients with CT-negative, LP-positive SAH was prospectively collected between 1998 and 2013. The yield of diagnostic modalities as well as patient outcome was studied. In addition, risk factors for the presence of a vascular lesion were analysed.
  
  
  RESULTS
  In 40 patients (43%), an intracranial vascular abnormality was detected: 37 aneurysms and three arterial dissections. Female gender was significantly associated with detection of a vascular lesion. Time between ictus and diagnosis of SAH was not associated with the presence of vascular pathology. Overall, 99% of patients had a modified Rankin Score of 0-2 after a median follow-up of 72 months. The yield of additional digital subtraction angiography in patients with a negative CT angiography was zero.
  
  
  CONCLUSIONS
  In this study, the chance of finding a vascular lesion in a patient with CT-negative, LP-positive SAH was 43%, underlining the need for an adequate diagnostic workup. In general, the patient outcome was favourable. Female gender was found to be predictive for detecting a vascular lesion. In contrast with previous reports, the interval between ictus and LP was not associated with the presence of an aneurysm.
authors.affiliation: Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Nicolaas A
authors.initials: NA
authors.lastname: Bakker
authors.affiliation: Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Rob J M
authors.initials: RJ
authors.lastname: Groen
authors.affiliation: Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Mahrouz
authors.initials: M
authors.lastname: Foumani
authors.affiliation: Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Uyttenboogaart
authors.affiliation: Department of Radiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Omid S
authors.initials: OS
authors.lastname: Eshghi
authors.affiliation: Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Jan D M
authors.initials: JD
authors.lastname: Metzemaekers
authors.affiliation: Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Gert Jan
authors.initials: GJ
authors.lastname: Luijckx
authors.affiliation: Department of Neurosurgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: J Marc C
authors.initials: JM
authors.lastname: Van Dijk
mesh_terms: D000328:Adult; D000368:Aged; D015901:Angiography, Digital Subtraction; D002533:Cerebral Angiography; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D019635:Neurosurgical Procedures / Q000379:methods; D012307:Risk Factors; D013129:Spinal Puncture; D013345:Subarachnoid Hemorrhage / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult