Viral meningitis: Which patients can be discharged from the emergency department?

Background: Even in an era when cases of viral meningitis outnumber bacterial meningitis by at least 25:1, most patients with clinical meningitis are hospitalized. Objective: We describe the clinical characteristics of an unusual outbreak of viral meningitis that featured markedly elevated cerebrospinal fluid white blood cell counts (CSF WBC). A validated prediction model for viral meningitis was applied to determine which hospital admissions could have been avoided. Methods: Data were collected retrospectively from patients presenting to our tertiary care center. Charts were reviewed in patients with CSF pleocytosis (CSF WBC > 7 cells/mm³) and a clinical diagnosis of meningitis between March 1, 2003 and July 1, 2003. Cases were identified through hospital infection control and by surveying all CSF specimens submitted to the microbiology laboratory during the outbreak. Results: There were 78 cases of viral meningitis and 1 case of bacterial meningitis identified. Fifty-eight percent of the viral meningitis cases were confirmed by culture or polymerase chain reaction to be due to Enterovirus. Mean CSF WBC count was 571 cells/mm³, including 20 patients with a CSF WBC count > 750 cells/mm³ (25%) and 11 patients with values > 1000 cells/mm³ (14%). Sixty-four of 78 patients (82%) were hospitalized. Rates of headache, photophobia, nuchal rigidity, vomiting, and administration of intravenous fluids in the Emergency Department were no different between admitted and discharged patients. Only 26/78 (33%) patients with viral meningitis would have been admitted if the prediction model had been used. Conclusions: Although not all cases of viral meningitis are necessarily suitable for outpatient management, use of a prediction model for viral meningitis may have helped decrease hospitalization by nearly 60%, even though this outbreak was characterized by unusually high levels of CSF pleocytosis.