Benign recurrent lymphocytic meningitis (Mollaret's meningitis) in Denmark: a nationwide cohort study

Abstract

Background and purposeData on clinical features and outcomes of benign recurrent lymphocytic meningitis (BRLM) are limited.MethodsThis was a nationwide population‐based cohort study of all adults hospitalized for BRLM associated with herpes simplex virus type 2 (HSV‐2) at the departments of infectious diseases in Denmark from 2015 to 2020. Patients with single‐episode HSV‐2 meningitis were included for comparison.ResultsForty‐seven patients with BRLM (mean annual incidence 1.2/1,000,000 adults) and 118 with single‐episode HSV‐2 meningitis were included. The progression risk from HSV‐2 meningitis to BRLM was 22% (95% confidence interval [CI] 15%–30%). The proportion of patients with the triad of headache, neck stiffness and photophobia/hyperacusis was similar between BRLM and single‐episode HSV‐2 meningitis (16/43 [37%] vs. 46/103 [45%]; p = 0.41), whilst the median cerebrospinal fluid leukocyte count was lower in BRLM (221 cells vs. 398 cells; p = 0.02). Unfavourable functional outcomes (Glasgow Outcome Scale score of 1–4) were less frequent in BRLM at all post‐discharge follow‐up visits. During the study period, 10 (21%) patients with BRLM were hospitalized for an additional recurrence (annual rate 6%, 95% CI 3%–12%). The hazard ratio for an additional recurrence was 3.93 (95% CI 1.02–15.3) for patients with three or more previous episodes of meningitis.ConclusionsClinical features of BRLM were similar to those of single‐episode HSV‐2 meningitis, whilst post‐discharge outcomes were more favourable. Patients with three or more previous episodes of meningitis had higher risk of an additional recurrence.