Raising Mean Arterial Pressure Alone Restores 20% of Intraoperative Neuromonitoring Losses

Study Design. Multicenter prospective. Objective. To assess the effect of intraoperative interventions in restoring intraoperative neuromonitoring (IONM) signals in pediatric spine surgery. Summary of Background Data. No prior studies have prospectively examined the rate of return of IONM signals by increasing blood pressure (BP) alone. Methods. Patients undergoing posterior spinal deformity surgery were enrolled at their preoperative appointment. Surgeons completed an intraoperative data form on patients who experienced an IONM change defined as a 50% or greater decrease in either transcranial motor evoked potentials or somatosensory evoked potentials. Results. Four hundred fifty two patients were enrolled with 30 (7%) having IONM change. Thirty patients met inclusion criteria (mean age, 12 yrs, range, 5-19) and had the following diagnoses: idiopathic scoliosis (43%), neuromuscular scoliosis (13%), congenital scoliosis (10%), early onset scoliosis (7%), and other (27%). 20% (6/30) had return of signals due to an increase in BP alone with no other interventions (mean arterial pressure [MAP] increased from mean of 68 [range, 58-76] to 86 mmHg [range, 75-95]). Signals returned to baseline after mean of 16 minutes (range, 2-45). In 60% of patients (18/30), MAP was raised from a mean of 72 mmHg (range, 55-84) to 86 mmHg (range, 75-100) in conjunction with other interventions and had mean return of signals in 37 minutes (range, 8-210). Six (20%) of patients had signals return to baseline after a mean of 6 minutes (range, 3-13) in which MAP did not change appreciably. All patients had return of signals at the conclusion of the procedure with one patient having postoperative neurological sequale. Conclusion. In this prospective study of 452 pediatric spinal deformity surgeries, raising MAPs above 85 mmHg should be considered the first step in response to IONM signal changes, as this alone was successful in 20% of patients without sacrificing deformity correction.