Evolving Diagnostic Approaches to Undocumented Lymphocytic Meningitis and Meningoencephalitis

Inclusion Criteria: * Individuals who have received full information regarding the organisation and conduct of the study * Adults or children * Hospitalised in a department of Nancy University Hospital with a diagnosis of lymphocytic meningitis or meningoencephalitis * Cerebrospinal fluid showing more than 5 cells/mm³, with either a negative FilmArray result or no FilmArray performed Exclusion Criteria: * Patients diagnosed with non-lymphocytic meningitis or meningoencephalitis * Patients with documented lymphocytic meningitis or meningoencephalitis of a known cause (excluding TBE) prior to the date the advisory was issued * Patients who have expressed opposition to the use of their data for this study