title: [Experimental research of myogenic motor evoked potentials to transcranial magnetic stimulation for spinal cord monitoring].
abstract: OBJECTIVE
  To evaluate the validity of intraoperative magnetic MEP (motor evoked potentials) monitoring in a spinal-cord-menaced surgery.
  
  
  METHODS
  32 rabbits were employed in weight-drop spinal cord contusion model. After anesthetized with a combination of Ketamine and Droperidol the spinal cords were surgically exposed with the dura intact, and the contusion injuries were delivered except the rabbits in control group. The MEPs were recorded and the relationship between the variation of the MEPs and the residual locomotor capacity after spinal cord injury was analyzed.
  
  
  RESULTS
  The 6 rabbits in mild-spinal-cord-injury group experienced transient attenuation of their TMS-MEPs, and the locomotor capacity remained intact (scores of 5) in almost all rabbits (5 of 6) when assessed 24 hours later; In the moderate-spinal-cord-injury group the 8 rabbits lost their TMS-MEP immediately after the weight-drop contusion, but they regained them partly in 1 hour one after another and scored 4 or 5 in the assessment of muscle power next day except for one score of 2; 8 rabbits had their spinal cords impaired severely in the contusion procedure and lost their TMS-MEP too but without recovery, their locomotor capacity outcomes were very poor, 5 of them had no response to transcranial magnetic stimulation next day, and in the other 3 rabbits we only found some polyphase waves with variant latency and lower amplitude which did not resemble common compound muscle action potential (CMAPs) evoked by TMS.
  
  
  CONCLUSIONS
  Myogenic TMS-MEPs was very sensitive to the spinal cord injury and should be a valid technique for intraoperative monitoring, and a slight change of them, even if a transient lose, should be unnecessarily related to a severe movement disorder. The warning threshold for a given patient should depend on the malady itself.
authors.affiliation: Department of Neurosurgery, Beijing Hospital, Beijing 100730, China.
authors.forename: Hong-wen
authors.initials: HW
authors.lastname: Xie
authors.forename: Shu-shan
authors.initials: SS
authors.lastname: Liu
authors.forename: Cheng-yuan
authors.initials: CY
authors.lastname: Wu
authors.forename: Cheng
authors.initials: C
authors.lastname: Sha
authors.forename: Da-ming
authors.initials: DM
authors.lastname: Wang
authors.forename: Chang-chun
authors.initials: CC
authors.lastname: Wang
authors.forename: Yu-ming
authors.initials: YM
authors.lastname: Yang
authors.forename: Ao
authors.initials: A
authors.lastname: Pei
mesh_terms: D000208:Acute Disease; D000818:Animals; D001921:Brain / Q000503:physiopathology*; D004195:Disease Models, Animal; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D008297:Male; D008991:Monitoring, Physiologic; D011379:Prognosis; D011817:Rabbits; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation