Mapping dermatomes during selective dorsal rhizotomy: Case report and review of the literature

Background: Studies suggest that the pattern of dermatomal segmental innervation in any given patient, may differ from the classic dermatomal maps first described in the 1890s. Such variability may limit the effectiveness of selective dorsal rhizotomy for treatment of neurogenic pain. Case Description: A 46-year-old male presented with a 27-year history of intractable pain in his left arm after being shot during the Vietnam War; multiple surgical and medical therapeutic modalities failed to produce durable pain relief. The patient underwent selective dorsal rhizotomy, with intraoperative dermatomal and mixed somatosensory evoked potential recordings. Pre- and postrhizotomy recordings were compared, effectively mapping this patient's dermatomal pattern. At 4 years' follow-up, the patient remains pain free. Conclusion: Intraoperative monitoring of somatosensory evoked potentials during dorsal rhizotomy for neurogenic pain can be used to establish the degree to which an individual's pattern of segmental innervation conforms to the traditionally described dermatomes.