DORSAL ROOT ENTRY ZONE LESIONS FOR PAIN RELIEF

Arm pain due to avulsion of the cervical dorsal roots of the brachial plexus may become intractable, ameliorated little, if at all, by contemporary medical or surgical treatment. Severe and sudden trauma to the neck, shoulder, or arm is the usual cause of avulsion of the cervical rootlets. The injury may result in complete sensorimotor paralysis of the involved extremity, or a partial deficit if only a few rootlets are involved. Previous therapies have included stellate block, sympathectomy, high cervical cordotomy, rhizotomy, transcutaneous stimulation, dorsal column stimulation, mesencephalic tractotomy, cingulotomy, and the use of narcotics. The extent of the pathological change in the spinal cord following root avulsion is not completely known; at the time of operation, abnormalities frequently noted included ipsilateral atrophy of the dorsal aspect of the cord, dense arachnoid scarring, microcyst formation, and loss of both dorsal and ventral roots. The cervical myelogram is abnormal, although not necessarily pathognomonic of the extent of injury. The surgical technique of coagulation of the dorsal root entry zone is discussed, and the results and morbidity in 21 patients are reviewed. Thirteen patients (67%) continue to have good pain relief, with follow-up periods ranging from 6 months to 3 1/2 years. Three patients with extremity pain from other causes are included in the series. Clinical observations suggest the possibility that pain resulting from brachial plexus avulsion originates from pathophysiological changes in the injured dorsal horn of the spinal cord. This report is a discussion of a new technique aimed at destruction of the dorsal root entry zone for relief of chronic extremity pain.