Human cortical motor representation of the larynx as assessed by transcranial magnetic stimulation (TMS).
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.
Rödel
Ralph M W
RM
University of Gottingen, Gottingen, Lower Saxonia, Germany.
Olthoff
Arno
A
Tergau
Frithjof
F
Simonyan
Kristina
K
Kraemer
Dorit
D
Markus
Holger
H
Kruse
Eberhard
E
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