# Transverse Myelitis: An Adverse Reaction to Abatacept

## TL;DR

A patient with rheumatoid arthritis developed transverse myelitis, a rare side effect, after long-term abatacept treatment, but recovered with corticosteroid therapy.

## Contribution

Highlights transverse myelitis as a rare but serious adverse reaction to abatacept in rheumatoid arthritis patients.

## Key findings

- The patient's transverse myelitis was linked to abatacept use.
- Discontinuing abatacept and starting corticosteroids led to a favorable outcome.
- This case underscores the need for awareness of rare immune-related adverse events with abatacept.

## Abstract

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.