Longitudinally extensive transverse myelitis associated with long-term adalimumab therapy: A diagnostic challenge.

A 48-year-old man with longstanding seronegative rheumatoid arthritis (RA) developed a progressive myelopathy characterized by sensory disturbances and gait ataxia. His symptoms emerged after four years of adalimumab therapy, prompting magnetic resonance imaging (MRI). MRI revealed a non-enhancing cervical cord lesion extending from C2 to C7. Testing for aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies was negative, and other etiologies were excluded. He showed a partial response to corticosteroids, and adalimumab was discontinued in favor of rituximab. This case underscores the importance of maintaining clinical vigilance for rare but serious neurological adverse effects associated with TNF-α inhibitors, particularly in cases of longitudinally extensive transverse myelitis (LETM).