title: Methodology for intraoperatively eliciting motor evoked potentials in the vocal muscles by electrical stimulation of the corticobulbar tract.
abstract: OBJECTIVE
  To establish a methodology for recording corticobulbar motor evoked potentials (CoMEPs) from vocal muscles after transcranial electrical stimulation (TES) and direct cortical stimulation (DCS).
  
  
  METHODS
  Twenty-four patients were included in this study (22 for TES, 2 for DCS, 3 for TES plus DCS) that underwent different surgical procedures. We used two methods to elicit CoMEPs: (a) TES by stimulation over C3/Cz or C4/Cz and (b) DCS with a strip electrode placed over the primary motor area (M1) for laryngeal muscles. To record CoMEPs from vocal muscles we used two hook wire electrodes 76 microm of diameter passing through 27 gauge needle endotracheally placed in the vocal muscles after intubation.
  
  
  RESULTS
  Recording of CoMEPs in the vocal muscles after TES was successfully performed in 22 patients. TES over the right or left hemisphere elicit responses bilaterally. The onset latencies for the right vocal muscle was 12.4+/-3.1 ms (ipsilateral stimulation) and 12.7+/-2.2 ms (contralateral stimulation) while for the left vocal muscle, onset latency was 12.9+/-2.3 ms (ipsilateral stimulation) and 14.1+/-3.4 ms (contralateral stimulation). In five patients DCS elicited CoMEPs in right and left vocal muscle with latency of 16.6+/-4.7 and 15.6+/-3.7 ms, respectively.
  
  
  CONCLUSIONS
  The method to elicit and record CoMEPs in vocal muscles shows reliable results and adds one more tool in the armamentarium of intraoperative neurophysiology.
  
  
  CONCLUSIONS
  This method shows the ability to continuously monitor the functional integrity of corticobulbar pathways, vagal nucleus and laryngeal nerves.
authors.affiliation: Department of Intraoperative Neurophysiology, St. Luke's Roosevelt Hospital, 1000 Tenth Avenue, Suite 1C-02, New York, NY 10019, USA.
authors.forename: Vedran
authors.initials: V
authors.lastname: Deletis
authors.forename: Isabel
authors.initials: I
authors.lastname: Fernandez-Conejero
authors.forename: Sedat
authors.initials: S
authors.lastname: Ulkatan
authors.forename: Peter
authors.initials: P
authors.lastname: Costantino
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004558:Electric Stimulation / Q000379:methods*; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D007821:Laryngeal Muscles / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011712:Pyramidal Tracts / Q000601:surgery*; D011930:Reaction Time; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult