Modified dorsal root entry zone lesioning for pain relief in cervical root avulsion injury Keisuke Takai, MD, PhD, and Makoto Taniguchi, MD, PhD Department of Neurosurgery, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan Neuropathic pain in the upper extremity due to cervical root avulsion injury is refractory to medical treatments. Superficial layers in the posterior horn of spinal gray matter, including the substantia gelatinosa, are the main target of dorsal root entry zone (DREZ) lesioning, which has been the most effective surgical treatment for the relief of intractable pain; however, residual pain and a decrease in pain relief during the long-term follow-up period have been reported. Based on pain topography in the most recent basic studies, the conventional DREZ lesioning procedure was modified to improve clinical outcomes.