title: Spinal Cord Monitoring With Transcranial Motor Evoked Potentials in Patients With Neural Axis Abnormalities Undergoing Spinal Deformity Surgery.
abstract: METHODS
  Retrospective, case-control study.
  
  
  OBJECTIVE
  To report the effectiveness of transcranial motor evoked potentials (TcMEPs) in patients undergoing scoliosis surgery with neural axis abnormalities (NAAs).
  
  
  BACKGROUND
  Transcranial motor evoked potentials are a safe and sensitive modality to identify impending spinal cord injury in adolescent idiopathic scoliosis (AIS). Previous studies have analyzed somatosensory evoked potentials (SSEPs) and neurogenic motor evoked potentials in NAA patients, but to our knowledge, no study has addressed the use of TcMEPs in these patients.
  
  
  METHODS
  We performed an institutional review board-approved retrospective review of a consecutive series of patients with NAA at a single institution and compared them with a consecutive series of AIS patients undergoing scoliosis surgery with spinal cord monitoring using TcMEP and SSEP. We compared the ability to obtain baseline data and the incidence of critical changes in TcMEPs and SSEPs between groups and examined a correlation with postoperative neurologic deficits.
  
  
  RESULTS
  We compared 38 patients with NAA (15 Chiari malformations, 12 syrinx, 7 tethered cords, and 4 spinal cord tumors) with 184 patients with AIS. The age was similar and preoperative curve magnitude was greater in the NAA group. Good baseline data were obtained less frequently in the NAA group for TcMEPs (94.7% vs. 100%; p < .001) and SSEPs (89.5% vs. 100%; p < .001). There was no statistical difference in critical deviation from baseline in the NAA group for TcMEPs (3 of 38 [7.9%] vs. 5 of 184 [2.7%]; p = .120) or SSEPs (0 of 38 vs. 3 of 184 [1.6%] (p = .430). There were no postoperative neurologic deficits in the NAA or AIS group.
  
  
  CONCLUSIONS
  The ability to obtain baseline spinal cord monitoring in patients with NAA approaches that of an AIS group and accurately identifies impending neurologic deficits with high sensitivity. Surgeons should be confident that TcMEP baseline data can be obtained in patients with spinal cord pathology and should trust critical changes in TcMEPs intraoperatively to prevent spinal cord injury.
authors.affiliation: Department of Orthopaedic Surgery, Lexington Shriners Hospitals for Children, 1900 Richmond Road, Lexington, KY 40502, USA. Electronic address: ryan.muchowrmuchow@shrinenet.org.
authors.forename: Ryan D
authors.initials: RD
authors.lastname: Muchow
authors.affiliation: Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: McClung
authors.affiliation: Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Rampy
authors.affiliation: Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Van Allen
authors.affiliation: Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Sparagana
authors.affiliation: Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn Street, Dallas, TX 75219, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Sucato
keywords: Neural axis abnormality; Neuromonitoring; Scoliosis; Transcranial motor evoked potential