Beyond the Joints: Rheumatoid Meningitis as a Neurological Manifestation of Rheumatoid Arthritis.

Rheumatoid meningitis (RM) is a rare and severe extra-articular neurological manifestation of rheumatoid arthritis. Headache is one of the most common symptoms along with focal neurological deficits, neuroinfective symptoms, including seizures, and altered mental status are prevalent. We present a case of a 58-year-old Mexican woman with a history of rheumatoid arthritis since 2018, with positive cyclic citrullinated peptide antibodies and rheumatoid factor. Her clinical presentation began with a right-sided hemicranial headache, which was followed by an acute confusional state and discrete left-sided hemiparesis. The first magnetic resonance imaging (MRI) of the brain revealed meningeal enhancement throughout the right cerebral hemisphere. Cerebrospinal fluid (CSF) analysis showed hyperproteinorrhachia, pleocytosis, and hypoglycorrhachia. A biopsy ruled out infectious and neoplastic processes, leading to a diagnosis of rheumatoid meningitis (RM). This study represents the diagnostic challenge posed by rheumatoid meningitis in the presence of unspecific neurological symptoms due to its similarity with other etiologies, which may delay adequate treatment. It also highlights the usefulness of diagnostic tools that can guide physicians in the early recognition of this pathology, improving the patient's prognosis.