Rheumatoid Meningitis Presenting Without Apparent Joint Symptoms: A Case Report Highlighting the Usefulness of Musculoskeletal Ultrasound

Rheumatoid meningitis (RM) is a rare central nervous system complication of rheumatoid arthritis. Symptoms of RM are diverse, including headache, convulsions, hemiplegia, movement disorders, cognitive decline, and consciousness disorders. Sometimes, RM can present neurological symptoms prior to joint symptoms, which can be a diagnostic challenge. Here, we report a case of RM without obvious arthritis symptoms, which was later diagnosed as RM supported by musculoskeletal ultrasound findings. The diagnosis of RM was made based on characteristic brain MRI findings, positive anti-cyclic citrullinated peptide antibodies (ACPA) in both serum and cerebrospinal fluid, an elevated ACPA index, and exclusion of infections and malignancy. Treatment with high-dose intravenous corticosteroid led to rapid clinical improvement. Our case highlights the diagnostic utility of musculoskeletal ultrasound in detecting subclinical arthritis and suggests its potential role in evaluating suspected RM even in the absence of joint symptoms.