Rheumatoid meningitis: a rare cause of unilateral pachymeningitis.

An 87-year-old woman with quiescent rheumatoid arthritis, not on immunosuppressive therapy, presented with unilateral arm weakness, confusion and visual hallucinations. There were no infective symptoms or history of malignancy. Cerebrospinal fluid (CSF) analysis demonstrated lymphocytosis and raised protein, without flow cytometric or cytological abnormalities.