To the Editor:
Anti-tumor necrosis factor-α (anti-TNF) therapy is a frequent therapeutic modality in patients with autoimmune disease. There is increased recognition that these agents may cause various inflammatory demyelinating neuropathies. We describe a 36-year-old man with Crohn’s disease who developed multifocal motor neuropathy with conduction block (MMNCB) after treatment with infliximab. He was diagnosed in 1997 with severe fistulizing Crohn’s disease. He was started on infliximab in hospital in February 2000 as he had not responded to treatment with azathioprine, metronidazole, and ciprofloxacin. He had 2 further infusions of infliximab in April and May 2000. On May 30, 2000, he underwent ileocolic resection. Preoperatively he reported mild hand numbness; postoperatively he developed progressive bilateral weakness of his wrists, finger extensors, and interossei as well as marked weakness in the extensors of his toes and moderate weakness of his ankle dorsiflexors. Sensation was preserved. Nerve conduction studies revealed mildly delayed ulnar F-wave latency at 32.7 ms. The remainder of the study was normal. Conduction block was not found. Electromyography revealed reduced recruitment in muscles of the upper and lower extremity, with fibrillation potentials and positive sharp waves identified in tibialis anterior, medial gastrocnemius, extensor digitorum, and first dorsal interosseus. The electrophysiological diagnosis was a motor neuropathy …
Address correspondence to Dr. Barber. E-mail: claire.barber{at}utoronto.ca