Diseases that mimic meningitis. Analysis of 650 lumbar punctures.

A retrospective review of charts for 650 children who had lumbar puncture for suspected meningitis was undertaken to determine the characteristics of patients with and without meningitis, identify other conditions suggesting meningitis, and evaluate the predictive value of signs and symptoms of meningitis. The incidence of positive lumbar punctures increased with patient age. Younger infants did not present with classical features of meningitis. Bulging fontanel, lethargy, and irritability were nonspecific symptoms. Vomiting and headache, although not specific, proved to be more sensitive indicators of meningeal infection. Most patients with meningitis (75%) had at least one sign of meningeal irritation, but so did 25% of patients without meningitis. Brudzinski's sign was not specific. In contrast, nuchal rigidity and Kernig's sign had high predictive value. Up to age five, the diseases most often suggesting meningitis were right-sided pneumonia, gastroenteritis, otitis, tonsillitis, exanthema subitum, and urinary tract infections. Of 171 patients with febrile convulsion, one (0.5%) had bacterial meningitis and four had aseptic meningitis.