title: A new measure for monitoring intraoperative somatosensory evoked potentials.
abstract: OBJECTIVE
  To propose a new measure for effective monitoring of intraoperative somatosensory evoked potentials (SEP) and to validate the feasibility of this measure for evoked potentials (EP) and single trials with a retrospective data analysis study.
  
  
  METHODS
  The proposed new measure (hereafter, a slope-measure) was defined as the relative slope of the amplitude and latency at each EP peak compared to the baseline value, which is sensitive to the change in the amplitude and latency simultaneously. We used the slope-measure for EP and single trials and compared the significant change detection time with that of the conventional peak-to-peak method. When applied to single trials, each single trial signal was processed with optimal filters before using the slope-measure. In this retrospective data analysis, 7 patients who underwent cerebral aneurysm clipping surgery for unruptured aneurysm middle cerebral artery (MCA) bifurcation were included.
  
  
  RESULTS
  We found that this simple slope-measure has a detection time that is as early or earlier than that of the conventional method; furthermore, using the slope-measure in optimally filtered single trials provides warning signs earlier than that of the conventional method during MCA clipping surgery.
  
  
  CONCLUSIONS
  Our results have confirmed the feasibility of the slope-measure for intraoperative SEP monitoring. This is a novel study that provides a useful measure for either EP or single trials in intraoperative SEP monitoring.
authors: Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea. ; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Korea.
authors: Seung-Hyun
authors: SH
authors: Jin
authors: Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea. ; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, Korea. ; Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea. ; Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, Korea.
authors: Chun Kee
authors: CK
authors: Chung
authors: Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea. ; Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.
authors: Jeong Eun
authors: JE
authors: Kim
authors: Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea.
authors: Young Doo
authors: YD
authors: Choi
keywords: Intraoperative neurophysiological monitoring; Single trials; Slope-measure; Somatosensory evoked potentials; Temporary clipping
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