title: Hypotension-induced loss of intraoperative monitoring data during surgical correction of scheuermann kyphosis: a case report.
abstract: METHODS
  Presentation of a case report of Scheuermann kyphosis surgical correction.
  
  
  OBJECTIVE
  To describe a scenario where both neurogenic mixed evoked potentials and somatosensory-evoked potentials were lost due solely to hypotension before any correction of a kyphotic spinal deformity was performed.
  
  
  BACKGROUND
  Multimodality intraoperative neurophysiologic monitoring of the spinal cord has become widely utilized during surgical correction of scoliotic and kyphotic deformities. Most spinal surgeries also benefit from a state of hypotension to minimize blood loss, but unchecked and persistent hypotension may lead to inadequate perfusion to the spinal cord, resulting in spinal cord dysfunction noted by diminution of neuromonitoring data.
  
  
  METHODS
  An 18-year-old boy with a 95 degrees Scheuermann kyphosis underwent a posterior spinal fusion for correction of his deformity. Intraoperative neurophysiologic monitoring consisting of neurogenic mixed evoked potentials and somatosensory-evoked potentials were performed throughout surgery.
  
  
  RESULTS
  After placement of segmental pedicle screw fixation points and multiple osteotomies, before any instrumented correction of the deformity, all lower extremity neuromonitoring data were acutely lost. The surgeon was immediately warned of the data loss, with the mean arterial pressure noted to be 50 mm Hg. The mean arterial pressure was raised with the use of epinephrine bolus and dopamine infusion. Subsequently, all lower extremity neuromonitoring data returned. A Stagnara wake-up test was performed, which the patient passed, and the surgical correction was performed with his pressure maintained on a dopamine infusion. He awakened without neurologic deficits and had an uneventful recovery.
  
  
  CONCLUSIONS
  Although a state of mild hypotension may be beneficial to limit blood loss during spinal deformity corrective surgery, acute and/or prolonged hypotension may jeopardize spinal cord vascularity and should be avoided especially during surgical treatment of high-risk deformities such as kyphosis. Early warning by multimodality physiologic neuromonitoring appears to be a useful method to alert surgeons of the potentially devastating problem of hypotension-induced spinal cord dysfunction and allows immediate corrective actions.
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Zanariah
authors.initials: Z
authors.lastname: Othman
authors.forename: Lawrence G
authors.initials: LG
authors.lastname: Lenke
authors.forename: Shelly M
authors.initials: SM
authors.lastname: Bolon
authors.forename: Anne
authors.initials: A
authors.lastname: Padberg
mesh_terms: D000293:Adolescent; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D007023:Hypotension, Controlled / Q000009:adverse effects*; D007738:Kyphosis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D016343:Monitoring, Intraoperative; D011859:Radiography