title: Alarm Value of Somatosensory Evoked Potential in Idiopathic Scoliosis Surgery.
abstract: BACKGROUND
  Somatosensory evoked potential (SSEP) monitoring is performed to examine postoperative clinical findings when a monitoring event was noted intraoperatively and to ascertain the alarm threshold for intraoperative neural damage.
  
  
  METHODS
  The tibial SSEP of both lower limbs was recorded intraoperatively in patients with idiopathic scoliosis. Change of SSEP amplitude as opposed to the baseline was categorized into 4 levels: decrease <40%, decrease of 40%-50%, decrease of 50%-60%, and decrease >60%. Postoperative neurologic function of patients was examined and compared with SSEP data.
  
  
  RESULTS
  The baseline amplitude before incision was significantly different from the amplitude after spine exposure. An amplitude reduction of >60% during scoliosis correction procedures was observed in 6 legs, and 4 of them had postoperative deterioration in motor status. As the measure of threshold for alarm, an amplitude reduction of >50% compared with baseline resulted in more false-positive outcomes compared with amplitude attenuation of >60%.
  
  
  CONCLUSIONS
  Compared with the traditional SSEP baseline before skin incision, the baseline acquired after spine exposure results in more accurate monitoring. A >60% decrease in SSEP amplitude could be a more suitable alarm threshold.
authors.affiliation: Department of Orthopaedics, the Second Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, China.
authors.forename: Sheng-Li
authors.initials: SL
authors.lastname: Huang
authors.affiliation: Department of Function Examination, Hong Hui Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, China.
authors.forename: Hua-Guang
authors.initials: HG
authors.lastname: Qi
authors.affiliation: Department of Neurology, the Second Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, China.
authors.forename: Jing-Jie
authors.initials: JJ
authors.lastname: Liu
authors.affiliation: Department of Function Examination, Hong Hui Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, China.
authors.forename: Jia-Liang
authors.initials: JL
authors.lastname: Li
authors.affiliation: Department of Orthopaedics, the Second Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, China.
authors.forename: Ya-Juan
authors.initials: YJ
authors.lastname: Huang
authors.affiliation: Department of Neurology, the Second Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, China. Electronic address: lixiangey@sina.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Xiang
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods*; D012189:Retrospective Studies; D012600:Scoliosis / Q000503:physiopathology* / Q000601:surgery*; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods*; D055815:Young Adult
keywords: Alarm criterion; Amplitude; Idiopathic scoliosis; Monitoring; Somatosensory-evoked potential