Short-term restoration of facial sensory loss by motor cortex stimulation in peripheral post-traumatic neuropathic pain

We report a case in which motor cortex stimulation (MCS) improved neuropathic facial pain due to peripheral nerve injury and restored tactile and thermal sensory loss. A 66-year-old man developed intractable trigeminal neuropathic pain after trauma of the supraorbital branch of the Vth nerve, associated with tactile and thermal sensory loss in the painful area. MCS was performed using neuronavigation and transdural electric stimulation to localize the upper facial area on the motor cortex. One month after surgery, pain was decreased from 80/100 to 20/100 on visual analogic scale, and sensory discrimination improved in the painful area. Two months after surgery, quantitative sensory testing confirmed the normalization of thermal detection thresholds. This case showed that MCS could restore tactile and thermal sensory loss, resulting from peripheral nerve injury. Although the mechanisms leading to this effect remain unclear, this observation enhanced the hypothesis that MCS acts through modulation of the sensory processing.