A0034 Chin Necrosis during Prone Positioning as a Consequence of Transcranial Motor Evoked Potential Monitoring in Spine Surgery: A Case Report

Background: Prone position is commonly used for surgeries of spine, posterior cranial fossa, retroperitoneal structures, gluteal region, and lower limbs. Incidence of iatrogenic neurological injuries is 23.8 to 65.4% for intramedullary spinal cord tumor resection without evoked potential monitoring. Transcranial motor evoked potential (TcMEP) monitoring is an important tool for intraoperative neurophysiological monitoring of corticospinal tract function during surgery.

Case Description: After taking written informed consent, a case of 40-year-old male, ASA I patient with D5–D7 intramedullary spinal cord tumor was posted for D5–D7 laminectomy and tumor excision. General anesthesia (GA) was induced, and after prone positioning was done with body supported on gel bolsters and head-on-head rest. Intraoperative TcMEP and SSEP monitoring was done, anesthesia was maintained with TIVA of propofol (100–200 µg/kg/min) and intermittent IV fentanyl. No neuromuscular blocker was used except during intubation. After completion of surgery, patient was turned supine. Redness, swelling, and paresthesia were found over the left side of the chin. All other neurological examinations were within normal limits. On postoperative day 1, the patch became black and necrotic. Intravenous dexamethasone 4 mg every 8 hours and oral chymotrypsin were given, and hydroheal ointment was applied locally. The patient was followed up, necrosis healed with scar formation after 2 months.

Conclusions: Prolonged surgeries in prone position need meticulous planning of patient positioning. Intermittent careful survey of positioning is important to prevent pressure-related complications, especially when TcMEP monitoring is used. Maintenance of proper hemodynamics, metabolic status, and good coordination with surgeons help avoid position-related complications.