title: Descending spinal cord evoked potentials in cervical spondylotic myelopathy: characteristic waveform changes seen at the lesion site.
abstract: OBJECTIVE
  To characterize waveform changes of descending spinal cord evoked potentials (D-SCEPs) seen in cervical spondylotic myelopathy (CSM).
  
  
  METHODS
  Intraoperative D-SCEP recording from serial intervertebral discs after transcranial electrical stimulation in 19 CSM patients with cord compression at a single level.
  
  
  RESULTS
  Compared to the baseline (100%) obtained one level rostrally, the D-SCEP recorded at the compression site showed a significantly (p<0.001) decreased amplitude (48%) and area (48%) of negative peak and increased amplitude (171%) and area (279%) of initial-positive peak. The degree in reduction of negative peak remained the same irrespective of the cord level involved, whereas enhancement of the positive peak tended to diminish with a more caudal compression.
  
  
  CONCLUSIONS
  In intraoperative electrophysiological studies of CSM with D-SCEP, an abrupt reduction of the negative peak accompanied by an enhancement of the initial-positive peak helps identify the site of conduction block. We speculate that progressive loss of the descending motor volleys at the synapses in the cervical enlargement may account for limited or absent enhancement of positive peak seen caudally.
  
  
  CONCLUSIONS
  The current finding helps us understand the pros and cons of various electrophysiologic techniques for intraoperative localization of maximal cord involvement in CSM.
authors.affiliation: Department of Orthopaedic Surgery, Kochi Medical School, Japan. Electronic address: nobuaki.tadokoro@gmail.com.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Tadokoro
authors.affiliation: Department of Orthopaedic Surgery, Kochi Medical School, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Tani
authors.affiliation: Department of Orthopaedic Surgery, Kochi Medical School, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikeuchi
authors.affiliation: Department of Orthopaedic Surgery, Kochi Medical School, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Takemasa
authors.affiliation: Department of Orthopaedic Surgery, Kochi Medical School, Japan.
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Kida
authors.affiliation: Department of Orthopaedic Surgery, Kuroshio Hospital, Japan.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Ikemoto
authors.affiliation: Multidisciplinary Pain Center, Aichi Medical School, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ushida
authors.affiliation: Department of Orthopaedic Surgery, Kansai Medical University Takii Hospital, Japan.
authors.forename: Shinichirou
authors.initials: S
authors.lastname: Taniguchi
authors.affiliation: Department of Neurology, University of Iowa, United States.
authors.forename: Jun
authors.initials: J
authors.lastname: Kimura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013116:Spinal Cord / Q000503:physiopathology*; D013117:Spinal Cord Compression / Q000503:physiopathology* / Q000601:surgery
keywords: Conduction block; D-wave; Descending spinal cord evoked potential; Referential recording; Transcranial electrical stimulation