Herpes simplex virus 2 meningitis: a retrospective cohort study

Herpes simplex virus 2 is a leading cause of viral meningitis and the most commonly recognized infectious cause of benign, recurrent meningitis. We report a retrospective, observational cohort study of patients with herpes simplex virus type 2 (HSV-2) meningitis, confirmed by polymerase chain reaction (PCR) in the cerebrospinal fluid (CSF). The terms “herpes simplex,” “meningitis,” or “encephalitis” were searched in the medical records system of the Mayo Clinic in Rochester, Minnesota (1995–2008). Patients were included if they had a clinical diagnosis of meningitis and HSV-2 detected by PCR in the CSF. There were 28 patients with 33 episodes identified (83 % female; mean age at presentation of meningitis 36 years, range 17–53; mean time to HSV2 detection from symptom onset 3 days, range 0–6; history of genital herpes 23 %). No patient took oral antiviral treatment at the time of presentation. Episodes were most likely to include headache (100 %), photophobia (47 %), self-reported fever (45 %), meningismus (44 %), and nausea and/or vomiting (29 %). CSF at the time of meningitis was notable for elevated protein (mean 156 g/dL, range 60–258) and white cell count (mean 504 cells/μL, range 86–1,860) with normal glucose (mean 54 mg/dL, range 32–80). Mollaret cells were never detected. Neuroimaging was most often normal (83 %) when performed, although some cases showed nonspecific (14 %) or meningeal changes (3 %). There was no consistent relationship to genital herpes. The duration of treatment with intravenous acyclovir ranged from 3 to 14 days for the first meningitic episode (daily dose range from 500 to 1,000 mg and total dose range from 500 mg q8h for 3 days to 800 mg q8h for 14 days). For subsequent episodes, the duration of treatment of intravenous acyclovir ranged from less than 1 to 14 days (total dose range from 1,390 mg for 1 day to 900 mg q8h for 10 days). The dose of valacyclovir ranged from 500 mg once daily to 500 mg four times daily. The median duration of valacyclovir treatment following the first episode was 10 days (range 3 to 14 days, n = 13). The median duration of valacyclovir treatment following a subsequent meningitic episode was 9 days (range 7 days to indefinite period, n = 9). No patient was reported to have seizures, neurological disability, or death in extended follow-up (mean follow-up 3.4 years). Recurrence of meningitic symptoms was not universal.