Neuroimaging in children with acute meningitis
Mactier et al's "lesson of the week" (1) concludes with a recommendation that all patients with suspected meningitis and decreased level of consciousness should have urgent brain imaging to exclude obstructive hydrocephalus before lumbar puncture.
It is most important to understand the limitations of neuroimaging in children with acute meningitis, and to avoid the commonly held misconception that lumbar puncture is safe if neuroimaging is normal. Lumbar puncture should be avoided in children with clinically diagnosed meningitis if consciousness is impaired or there are clinical signs of raised intracranial pressure, as it may precipitate herniation of the brain or coning. It has been clearly shown that coning may occur after lumbar puncture in children with meningitis even when neuroimaging has been normal (2).
Brain imaging is of no value in the immediate diagnosis of meningitis and is an insensitive method for the detection of raised intracranial pressure (3). The role of brain imaging is to identify complications of meningitis or to exclude focal brain pathology simulating meningitis. Positive indications for CT or MRI are progressive focal neurological signs, prolonged decreased level of consciousness, prolonged or focal seizures, increasing head circumference, evidence of continuing infection or recurrence of symptoms. Brain imaging should not be undertaken until after initiation of antibiotic therapy, control of raised intracranial pressure, and, if necessary, intubation and ventilation.
1. Mactier H, Galea P, McWilliam R. Lesson of the week. Acute obstructive hydrocephalus complicating bacterial meningitis in childhood.
2. Rennick G, Shann F, de Campo J. Cerebral herniation during bacterial meningitis in children. BMJ 1993;306:953-5
3. Heyderman RS, Robb SA, Kendall BE, Levin M. Does computed tomography have a role in the evaluation of complicated acute bacterial meningitis in childhood? Dev Med Child Neurol 1992;34:870-875
Competing interests: No competing interests