Phase reversal of somatosensory evoked potentials triggered by gracilis tract stimulation: case report of a new technique for neurophysiologic dorsal column mapping.

摘要: Background and importance : Reliable visual identification of the median raphae, essential for preservation function posterior dorsal columns during intramedullary spinal cord tumor resection, is not possible in many cases, because distorted local anatomy. In such intraoperative neurophysiologic mapping offers invaluable information to surgeon, guides myelotomy. We hereby describe a new technique. Clinical presentation A 41-year-old man with C3-C4 underwent successful myelotomy resection. Dorsal column was performed by use an 8-contact minielectrode strip placed on cord. Direct electrical stimulation applied via 2 adjacent contacts at time, attempt stimulate succession left right columns. Somatosensory evoked potentials (SSEPs) were recorded after each stimulation, scalp electrodes. sharp change polarity SSEPs (phase reversal) indicated when opposite occurred. Myelotomy between identified as being situated closest raphe. The tibial continuously monitored until dura closure. No changes from premyelotomy present. Postoperatively, patient had function. Conclusion SSEP phase-reversal technique promising method identify midline Fast easy perform, its final role awaits confirmation future applications.