Chronic immune-mediated demyelinating polyneuropathy in the setting of cetuximab treatment.

Cetuximab, a chimeric mouse/human monoclonal antibody directed against the epidermal growth factor receptor, is commonly used in colorectal and head and neck cancer. We describe an acquired neuropathy associated with cetuximab treatment in a patient with squamous cell carcinoma of the tongue. Our patient was treated with cetuximab from May to July 2008. In December 2008, he first noticed numbness in his feet. He progressed over the next 5 months to develop weakness in both legs, a lack of sensation up to his knees, pain in the dorsum of his feet with a burning sensation, and difficulty ambulating to the point of requiring a walker. He also had numbness in his fingertips and was unable to use his hands for fine movements. Electrodiagnostic studies demonstrated prolonged distal latencies, conduction block, and prolonged F-wave latencies, consistent with a diagnosis of definite CIDP according to EFNS/PNS criteria. Low amplitude potentials were noted in nerves of the lower extremities, indicative of secondary axonal loss. Extensive workup for an alternative cause was negative. He improved clinically after IVIG and corticosteroid treatment. We cannot strongly establish a causal relationship in this case, as 5 months elapsed between cetuximab treatment and the onset of neuropathic symptoms. Nonetheless, clinical vigilance is recommended when evaluating patients for neuropathy who have received cetuximab.