Meningococcal meningitis and a negative cerebrospinal fluid: case report and its medicolegal implications

A normal result on the initial cerebrospinal fluid (CSF) study has been traditionally used to exclude the potential diagnosis of bacterial meningitis. However, there have been a number of case studies of bacterial meningitis confirmed by CSF culture, in which an initial lumbar puncture yielded completely normal parameters. A review of the literature reports the frequency of this scenario to arise in 0.5% to 12% of cases. This might result in the delay of appropriate treatment for this potentially fatal condition. We report a 21-year-old female patient who presented with a clinical picture compatible with bacterial meningitis but with a normal initial CSF result. Neisseria meningitidis was later cultured from her CSF. The medicolegal aspects surrounding such a scenario, and its implications towards clinical practice are discussed. We conclude that an abnormal initial CSF study might indicate a diagnosis of bacterial meningitis but a normal result does not exclude it and should not delay early institution of appropriate antimicrobial therapy.