These results will help shape imaging protocols to better detect conditions with non-uniform nerve enlargements.

We report 2 cases of Lewis-Sumner syndrome (LSS) diagnosed in patients suffering from rheumatoid arthritis undergoing treatment with the antitumor necrosis factor alpha (TNF-alpha) monoclonal antibody infliximab. While experiencing clinical improvement in their arthritic symptoms, both patients experienced sensory deficits and weakness in multiple nerve distributions. They had electrodiagnostic evidence of motor conduction block and subsequent improvement with intravenous immunoglobulin (IVIg). We describe the details of the cases and review the literature on immune-mediated neuropathies associated with anti-TNF-alpha therapy.

A 52-year-old, previously healthy, right-handed male livestock trader woke in the middle of the night with acute, 9/10 right shoulder and forearm pain. He was unable to go back to sleep because of the pain, despite taking analgesics. The following day, he noticed weakness in his right hand and presented to the emergency department. He was found to have severe right shoulder pain and decreased active range of motion. Hand weakness was not documented. A presumptive diagnosis of inflammatory arthritis was made. Blood work showed normal complete blood count, electrolytes, creatinine kinase and erythrocyte sedimentation rate and elevated hepatic enzymes: aspartate aminotransferase 205 (normal range 16-51) U/L, alanine aminotransferase 472 (normal < 52) U/L, lactate dehydrogenase 861 (normal range 230-490) U/L, γ-glutamyl transferase 442 (normal range 5-38) U/L, and alkaline phosphatase 186 (normal range 36-144) U/L. The elevated hepatic enzymes were felt to be unrelated to the working diagnosis. The patient was prescribed prednisone 50 mg orally daily and analgesics and instructed to follow up with his family physician.The following day, he presented to the emergency department again. Pain had spread to his left arm and right-hand weakness had progressed, leading to difficulty performing activities of daily living. An examination showed that he was unable to flex the first or second digits of his right hand; no other neurologic abnormalities were noted. Radiographs of the upper extremity were unremarkable. The case was discussed over the phone with the on-call neurologist, who felt the symptoms were likely related to the peripheral nervous system. Referral to neuromuscular medicine was recommended.We assessed the patient in the neuromuscular medicine clinic 6 days after symptom onset. He had discontinued prednisone after 1 dose owing to perceived ineffectiveness. He described a constant, deep, aching 8/10 pain in both shoulders and forearms. He said he had no neck pain or sensory symptoms. Examination showed weakness in multiple nerve territories (Table 1), most notably in the anterior interosseous nerve (AIN) distribution, a branch of the median nerve. The patient could not flex the distal interphalangeal joints of digits 1 or 2 on the right (Figure 1) and had bilateral scapular winging (Figure 2). He had decreased sensation in the right axillary nerve territory. Reflexes were present (2+) and symmetric.

Discordance between patient perception and electrodiagnostic results regarding which hand is affected more severely in patients with CTS should alert the clinician to possible coexisting nonneurologic pathology and prompt regional musculoskeletal examination as indicated.