[An uncommon form of delayed radio-induced brachial plexopathy].

Radiation therapy of the neck or axillary areas for cancer may result in delayed brachial plexus palsy. Differential diagnosis between radiation and tumor brachial plexopathy is difficult. We report the case of a 38-year-old woman, treated by radiation therapy for osteosarcoma of the humeral head 22 years before, who exhibited a rapidly progressive incomplete hand palsy. EMG study revealed a conduction block at the level of the lateral cord. In this case, MRI could not distinguish between a delayed radiation injury and tumor infiltration. The diagnosis was clarified with an ultrasonographic examination. Neurolysis and epineurotomy of the median trunk in the brachial and axillary areas were performed. Histological examination confirmed radiation-induced nerve injury. The characteristics of this uncommon form are reviewed with regard to the previously reported descriptions.