Seronegative neurobrucellosis-do we need new neurobrucellosis criteria?

Neurobrucellosis presents in various clinical forms and should always be considered in neurological patients in highly endemic areas such as the Mediterranean basin. Establishing a diagnosis can be challenging since serological testing can sometimes yield negative results. We present a rare case of a seronegative relapse of neurobrucellosis in a patient who had been successfully treated for systemic brucellosis. Oligoclonal bands, an agglutination test, and 16S rRNA sequencing of cerebrospinal fluid proved essential in unmasking a confined central nervous system relapse. This case reinforces the need for establishing diagnostic criteria for neurobrucellosis, which could potentially include oligoclonal bands and an agglutination test on the cerebrospinal fluid.