title: Rare true-positive isolated SSEP loss with preservation of MEPs response during scoliosis correction.
abstract: METHODS
  Case report.
  
  
  OBJECTIVE
  To report a case of a true-positive isolated somatosensory evoked potential (SSEP) loss with preservation of motor evoked potential (MEP) response during scoliosis correction.
  
  
  BACKGROUND
  Combined intraoperative monitoring uses SSEPs and MEPs to decrease the probability of observing false-negative events. In combination, SSEPs and MEPs have become a standard of care for spinal deformity surgery. However, literature review reveals several cases of false-negative response with combined SSEPs and MEPs, raising the contention that intraoperative monitoring does not reliably identify all isolated selective spinal cord dysfunction.
  
  
  METHODS
  A 15-year-old female patient with a 65° right thoracic adolescent idiopathic scoliosis underwent correction and posterior spinal fusion with segmental pedicle screw instrumentation. After capture and derotation of the left concave rod, left-sided irreversible SSEP loss occurred whereas MEPs remained unchanged. After excluding systemic factors, anesthetic causes, or technical fault, deformity correction was released and instrumentation removed. No cortical breach was reported during pedicle screw removal.
  
  
  RESULTS
  Postoperatively, no clinical sensory or motor deficit was present; computed tomography demonstrated a burst left pedicle at T10 with the medial pedicle wall fragment in direct contact with the dorsal spinal cord. Magnetic resonance imaging excluded cord edema or other evidence of injury. Three days after surgery, intraoperative monitoring showed delayed latencies and amplitudes of the left SSEP. An uneventful reinsertion of instrumentation and correction excluding the left T10 pedicle screw was performed 7 days after the initial surgery.
  
  
  CONCLUSIONS
  This case report provides evidence of selective posterior spinal cord dysfunction with sparing of the anterior columns immediately after a correction maneuver and emphasizes the importance of simultaneous SSEP and MEP monitoring. To the authors' knowledge, there is no previous report of a true-positive isolated SSEP loss with preservation of MEP response during scoliosis correction.
  
  
  METHODS
  N/A.
authors.affiliation: From the Scottish National Spine Deformity Service Royal Hospital for Sick Children Edinburgh and Royal Infirmary of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Félix
authors.initials: F
authors.lastname: Tomé-Bermejo
authors.forename: Enrique
authors.initials: E
authors.lastname: Garrido
authors.forename: Michael
authors.initials: M
authors.lastname: Glasby
authors.forename: Sharon
authors.initials: S
authors.lastname: Thinn
mesh_terms: D000293:Adolescent; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D016343:Monitoring, Intraoperative; D012600:Scoliosis / Q000503:physiopathology / Q000601:surgery*; D013116:Spinal Cord / Q000503:physiopathology*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods; D013904:Thoracic Vertebrae / Q000601:surgery*; D016896:Treatment Outcome