Lumbar puncture and brain herniation in acute bacterial meningitis: a review.

There has been controversy regarding the risk of cerebral herniation caused by a lumbar puncture (LP) in acute bacterial meningitis (ABM). This review discusses in detail the issues involved in this controversy. Cerebral herniation occurs in about 5% of patients with ABM, accounting for about 30% of the mortality. In many reports, LP is temporally strongly associated with this event of herniation and is most likely causative based on pathophysiologic arguments. Although a computed tomography (CT) scan of the head is useful to find contraindications to an LP, a normal CT scan in ABM does not mean that an LP is safe. Clinical signs of "impending" herniation are the best predictors of when to delay an LP because of the risk of precipitating herniation, even with a normal CT scan. Some of these clinical signs to be considered are deteriorating level of consciousness (particularly to a Glasgow Coma Scale of