DORSAL-ROOT ENTRY ZONE LESIONS IN THE TREATMENT OF PAIN RELATED TO RADIATION-INDUCED BRACHIAL PLEXOPATHY

Radiation-induced brachial plexopathy (RBP) is a rare (1-2% of irradiated patients) but serious disorder associated with supramaximal irradiation of the brachial plexus. Nerve compression by radiation-induced fibrosis in the absence of tumor recurrence is the hypothesized mechanism of RBP. It appears as severe pain in up to 20% of cases. Current medical and surgical therapies are ineffective in obtaining long-term pain control. Dorsal root entry zone (DREZ) lesions represent a potential therapy for the pain associated with RBP. The records of two patients with RBP with severe pain successfully treated with DREZ lesions are reviewed. Each received supramaximal radiation to the brachial plexus following resection of the malignancy and had pain within the irradiated area approximately 1 year following radiation without evidence of tumor recurrence by either computed tomography or magnetic resonance imaging. Electromyography patterns consistent with RBP were detected within the irradiated area in both patients. Pain was in the C8-T1 distribution and described as sharp and burning. Both patients failed to obtain pain relief with prior medical and/or surgical procedures. Histologic sections of nerves were taken at surgery and confirmed the diagnosis of radiation-induced injury. Within the immediate postoperative period both patients experienced excellent pain relief and continue to be pain free at 29-48-month follow-up observation. The DREZ lesions provide a safe and effective therapy for the pain associated with RBP.