[Cranial computed tomography, lumbar puncture and clinical deterioration in bacterial meningitis: a nationwide cohort study].

BACKGROUND: Investigate how often cerebral herniation occurs following lumbar puncture (LP) in patients with bacterial meningitis, and whether cranial computed tomography (CT) can be used to identify patients at a higher risk of cerebral herniation. STUDY DESIGN: Prospective, nationwide cohort study covering the period March 2006 - November 2014. METHOD: We identified patients with community-acquired bacterial meningitis who showed signs of clinical deterioration, possibly caused by LP. For systematic evaluation of contraindications for LP on cranial CT, the included patients were matched to bacterial meningitis patients without deterioration. Four experts, blinded for patient outcome, scored cranial CT scan imaging for the cases as well as control patients in relation to contraindications for LP. Inter-assessor reliability was determined with Fleiss' generalized κ. RESULTS: Of the 1533 bacterial meningitis patients included, 47 (3.1%) exhibited clinical deterioration possibly caused by LP. Two patients deteriorated within 1 hour after LP (0.1%). In 43 of 47 patients that showed signs of clinical deterioration, cranial CT was performed prior to LP. The inter-rater reliability of assessment of contraindications for LP on cranial CT was moderate (Fleiss' generalized κ = 0.47). A contraindication for LP was reported by all four raters in 6 patients with clinical deterioration (14%) and in 5 patients without clinical deterioration (11%). CONCLUSION: LP can be performed safely in the large majority of patients with bacterial meningitis, as it only very rarely results in cerebral herniation. Cranial CT can be considered a screening method to identify patients who are at a higher risk of cerebral herniation, but the inter-rater reliability of the CT scan assessment for contraindications of LP is moderate.