A normal CT scan does not mean a safe lumbar puncture
There is a commonly held belief, reiterated by Dr Czech, one of your
correspondents, that it is safe to lumbar puncture patients with
meningitis provided they have normal CT scan appearances. This has led to
increasing numbers of requests for imaging to "exclude raised intracranial
pressure". There is no evidence base to support this assertion. In the
published series, almost all in the paediatric age group, there is
considerable evidence that the clinical features of depressed
consciousness, fits, papilloedema, and focal neurological signs are
contraindications to lumbar puncture (1,2,3). Even if the CT appearances
are normal patients have gone on to die from conning (1,4). We have found
evidence at our centre that the false reassurance of CT scanning appears
to be leading to neglect of the clinical contraindications (5).
A normal CT scan does not equal a safe lumbar puncture.
1. Rennick G, Shann F, de Campo J. Cerebral herniation during
bacterial meningitis in children. BMJ 1993;306;953-5
2. Mellor DH. The place of computed tomography and lumbar puncture in
suspected bacterial meningitis. Arch Dis Child 1992;67;1417-1419
3 Durand M, Calderwood S, Weber D et al. Acute bacterial meningitis
A review of 493 episodes. New Eng J Med 1993;328;21
4. Rosenberg et al Neurointensive care for cerebral herniation in
childhood meningitis. In Intracranial pressure. Proceedings of the 7th
international symposium on intracranial pressure. Springer Berlin 1989.
5. Cooper JR. Letter: Routine use of CT prior to lumbar puncture.
British Journal of Radiology 1999;72;319
Competing interests: No competing interests