Clinical characteristics of enteroviral meningitis without pleocytosis in children: a retrospective single center observational study in the Republic of Korea

Background We aimed to study the prevalence of enterovirus (EV) meningitis without the presence of cerebrospinal fluid (CSF) pleocytosis and identify patient factors and clinical features associated with it. Methods This was a retrospective analysis of patients aged < 18 years old who were diagnosed with EV meningitis by CSF reverse-transcriptase polymerase chain reaction (RT-PCR) testing between January 2015 and December 2016. Clinical variables were compared with regard to the presence of CSF pleocytosis. Results A total of 305 patients were enrolled in study; 169 (55.4%) had no pleocytosis. Patients without pleocytosis were younger (median age 2 months vs. 67.0 months, p < 0.01) and had lower white blood cell (WBC) count (median, 8600/mm(3) vs. 10,300/mm(3), p < 0.01). Also absolute neutrophil (ANC) count were lower than pleocytosis group (median, 4674/mm(3) vs. 7600/mm(3), p < 0.01). Comparing three age groups, CSF apleocytosis was present in 106 of 128 patients (82.8%) aged <= 3 months, 7 of 13 patients (53.8%) aged 3 months-3 years and 56 of 164 patients (34.1%) aged > 3 years. Younger age groups had higher prevalence of CSF apleocytosis (p < 0.01). In patients aged <= 3 months, 94.5% underwent lumbar puncture within 24 h of symptom onset. The frequency of not having pleocytosis was higher than the frequency of having pleocytosis during peak EV infection prevalent months (summer and fall) (p < 0.01). Conclusion This study shows that EV meningitis in young infants, with early lumbar puncture, or occurring during peak EV meningitis prevalent seasons cannot be solely excluded by pleocytosis. Also, a confirmation test for EV meningitis should be performed using RT-PCR.