Abstract
Transcranial motor evoked potential (MEP) is a common method in spinal surgery but requires strong electrical stimulation. Frequent transcranial stimulations can cause bite injury. In addition, a facial pressure ulcer is a problem in spinal surgery requiring prone positioning. We present a case of bite injury and facial pressure ulcer in prolonged lumbar tumor surgery with repeated transcranial stimulations. A 74-year-old woman developed left lower limb and low back pain. MRI revealed an intradural extramedullary tumor at L1. We performed tumor resection surgery. A silicon bite block was used, and the patient's head was placed on a sponge headrest. The tumor was a schwannoma originating from the nerve root that innervated the left anal sphincter. Intracapsular resection was performed while referring to the frequent transcranial MEP monitoring. The left lower limb and low back pain improved after surgery; however, lip injury and facial skin ulcer occurred. The face showed marked swelling and was painful, so oral intake was difficult for a week. Wound healing was obtained three months postoperatively, but hypoesthesia remained. When using MEP in prolonged spine surgery with a headrest, it is necessary to pay attention to both bite injury and facial pressure ulcer. Intraoperative assessment of the face, number of transcranial stimulations, types of a bite block, and headrest may be important.