Mrs. Ellis (a pseudonym) is a 57-year-old woman with a 10-year history of rheumatoid arthritis (RA) and a previous episode of transverse myelitis with residual pain and weakness.After the patient's insufficient response to methotrexate (MTX) and upon realizing that tumor necrosis factor inhibitors are relatively contraindicated in demyelinating disease, I wrote a prescription for abatacept (ABA), which could conceivably help both her RA and her transverse myelitis.