Tactile stimulation of a coin-sized area in a T-2 dermatome consistently triggered a lancinating pain in the ipsilateral C-8 dermatome in a 38-year-old woman. The SEP and an MRI led to a diagnosis of a tumor at the left cervico-medullary junction, much higher than the clinically suspected level. Surgical exploration revealed an exophytic glioma, and the pain was abolished postoperatively. Ephaptic transmission at the tumor site was suspected as a pathophysiologic mechanism.