(P95) Enterovirus Meningitis Without Pleocytosis Is Not Only a Problem in Children: A Retrospective Observational Study in Adults

Objectives: We evaluated the prevalence of EV meningitis without pleocytosis and examined differences in characteristics among patients with EV meningitis according to the presence of CSF pleocytosis in adults who visited the ED.

Background: EV meningitis and encephalitis are diagnosed by inflammatory changes in the cerebrospinal fluid (CSF), including pleocytosis and abnormal protein and glucose levels. Viral culture was previously used to confirm EV meningitis, but in the 2000s, reverse-transcriptase polymerase chain reaction (RT-PCR) was shown to be as accurate as culture and became the new gold standard to confirm diagnosis. Previous studies have reported a lack of pleocytosis with EV meningitis. Most reported cases of EV meningitis without pleocytosis diagnosed by CSF RT-PCR have been studied in pediatric populations. However, we don't know the adult presentation.

Methods: The present study retrospectively analyzed the medical records of patients with EV meningitis confirmed by cerebrospinal fluid (CSF) RT-PCR. We reviewed the data of patients older than 19 years who visited the emergency department (ED) between May 2016 and May 2021. Clinical and laboratory variables were compared according to the presence of CSF pleocytosis.

Results: Among 17 patients included, 10 (58.8%) did not have pleocytosis. The mean age was not different between the pleocytosis and the non-pleocytosis group (37.50 vs 33.50 years old, P=0.22). There were no significant differences between two groups regarding clinical symptoms, such as headache, fever, and meningeal irritated signs. All patients visited the ED from April to October only. There were no statistically significant differences between the two groups in terms of seasonal variation or time from the onset of meningitis symptoms to undergoing lumbar puncture. The peripheral white blood cell (WBC) count of the pleocytosis group was 10.9 × 109/L with 81.95% neutrophils, which was significantly higher than in patients without pleocytosis (WBC, 7.15 × 109/L and 66.65% neutrophils, P=0.04). The median CSF pressure showed higher trend in the non-pleocytosis group than the pleocytosis group (175.00 vs 152.50 mmH2O, P=0.70). Patients whose CSF pressure was higher than the normal level of 200.00 mmH2O were more common in the non-pleocytosis group (40%). The median CSF protein values were higher than the normal values in both groups.

Conclusions: The present study confirmed a high frequency of EV meningitis without pleocytosis in adult patients. An accurate diagnosis using RT-PCR is necessary when meningitis symptoms are prominent during an EV epidemic and CSF protein levels and pressure are high, even if the CSF WBC count is normal.

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Funding (Optional): None