Dorsal root entry zone microcoagulation for spinal cord injury-related central pain: operative intramedullary electrophysiological guidance and clinical outcome

Object. Surgically created lesions of the spinal cord dorsal root entry zone (DREZ) to relieve central pain after spinal cord injury (SCI) have historically resulted in modest outcomes. A review of the literature indicates that fair to good relief of pain is achieved in approximately 50% of patients when an empirical procedure is performed. This study was undertaken to determine if intramedullary electrical guidance in DREZ lesioning could improve outcomes in patients with SCI-induced central pain. Additionally, electrical data were used to determine if the spinal cord could be somatotopically mapped with regard to this pain of central origin. Methods. Forty-one patients with traumatic SCI and intractable central pain underwent DREZ lesioning in which intramedullary electrical guidance was conducted. In nine patients, recording of DREZ-related spontaneous electrical hyperactivity guided the lesioning process. In 32 patients, recording of DREZ-induced evoked electrical hyperactivity during transcutaneous C-fiber stimulation (TCS) additionally guided lesioning. The follow-up period ranged from 1 to 7 years. The analyzed electrical data allowed for somatotopic mapping of the spinal cord. Conclusions. Intramedullary electrical guidance of DREZ lesioning substantially improves pain outcomes in patients with traumatic SCI-induced central pain, compared with an empiric technique. The best outcome occurs when DREZ-related spontaneous electrical hyperactivity and evoked hyperactivity during TCS are both used to guide the DREZ lesioning procedure. With such guidance, 100% relief of pain was achieved in 84% of patients and 50 to 100% relief of pain in 88%. Somatotopic mapping of the electrical data led to a proposed pain mechanism for below-level pain, implicating the sympathetic nervous system.