title: Human cortical motor representation of the larynx as assessed by transcranial magnetic stimulation (TMS).
abstract: OBJECTIVE
  To analyze characteristic features and details on motor-evoked potentials (MEPs) of the cricothyroid and vocalis muscles from single-pulse cortical transcranial magnetic stimulation (TMS) in normal subjects to characterize cortical motor representation of laryngeal muscles.
  
  
  METHODS
  Prospective, experimental investigation on healthy volunteers.
  
  
  METHODS
  MEPs of the cricothyroid and vocalis muscles elicited by cortical TMS with a figure-8-shaped coil were investigated in two groups of six healthy subjects each, with special regard to MEP amplitude as a function of the coil position on the head surface along the interaural line.
  
  
  RESULTS
  Bilateral reproducible responses of the cricothyroid and the vocalis muscles could be observed in all subjects. For the cricothyroid muscle, maximal responses were obtained at mean stimulus positions of 7.5 +/- 1.4 cm (contralateral) and of 7.3 +/- 1.3 cm (ipsilateral), respectively. For the vocalis muscle, we found maximal responses at mean stimulus positions of 10.3 +/- 1.9 cm (contralateral) and of 9.6 +/- 1.6 cm (ipsilateral), respectively. Despite a considerable overlap of these coil positions, from which reproducible MEPs could be elicited in both groups of the laryngeal muscles, statistically significant separation of the cricothyroid-and vocalis-associated cortical representation areas was possible.
  
  
  CONCLUSIONS
  Our observations point to two different cortical motor representation areas, with the cricothyroid muscle-related area being located more medially.
authors.affiliation: University of Gottingen, Gottingen, Lower Saxonia, Germany.
authors.forename: Ralph M W
authors.initials: RM
authors.lastname: Rödel
authors.forename: Arno
authors.initials: A
authors.lastname: Olthoff
authors.forename: Frithjof
authors.initials: F
authors.lastname: Tergau
authors.forename: Kristina
authors.initials: K
authors.lastname: Simonyan
authors.forename: Dorit
authors.initials: D
authors.lastname: Kraemer
authors.forename: Holger
authors.initials: H
authors.lastname: Markus
authors.forename: Eberhard
authors.initials: E
authors.lastname: Kruse
mesh_terms: D000328:Adult; D003413:Cricoid Cartilage / Q000502:physiology; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D007821:Laryngeal Muscles / Q000502:physiology; D007830:Larynx / Q000502:physiology*; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology; D014827:Vocal Cords / Q000502:physiology