Transverse Myelitis: An Adverse Reaction to Abatacept

Immunotherapies are powerful disease-modifying agents in treating autoimmune diseases like rheumatoid arthritis (RA). However, their unique mechanisms of action confer a broad spectrum of immune-related adverse events (irAEs), which tend to be rare but complex, with significant risk for morbidity and mortality. We report a case of transverse myelitis in a patient with RA whose joint disease had been well-controlled with long-term intravenous abatacept. Suspicion of an unusual irAE in this elderly patient, whose neurologic symptomatology was gradual and protracted, prompted the discontinuation of abatacept and the rapid initiation of corticosteroid therapy. These interventions yielded a favorable clinical outcome for the patient. We must draw clinicians' attention to this rare but potentially consequential adverse drug reaction.