Determination of the optimal conditions for laryngeal pacing with the Itrel II implantable stimulator.
OBJECTIVE
To determine the optimal stimulus paradigm, electrode orientation, and configuration of an implantable stimulator used to reanimate the posterior-cricoarytenoid (PCA) muscle in case of bilateral vocal fold paralysis (BVFP).


METHODS
Acute studies were conducted on 13 canines implanted with Itrel II systems with or without PCA innervation. PCA stimulus-response characteristics were obtained by measuring stimulated vocal fold displacement endoscopically.


RESULTS
The denervated PCA was only 10% to 25% as responsive to stimulation as the innervated PCA. However, the response could be increased to 38% and 61% if the Itrel was modified to deliver 1 and 2 msec pulses, respectively. Stimuli delivered centrally to the muscle 5 mm from the median raphe improved performance.


CONCLUSIONS
The optimal stimulus paradigm identified in this study (1 msec pulses delivered at 30 to 40 Hz and 2 to 8.5 mA) has been applied to implanted BVFP patients and improved outcome. Information regarding optimal electrode orientation could also be important to future clinical trials.
Zealear
D L
DL
Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University, Nashville, Tennnessee 37232, USA. david.l.zealear@vanderbilt.edu
Swelstad
M R
MR
Sant'Anna
G D
GD
Bannister
R A
RA
Billante
C R
CR
Rodriguez
R J
RJ
Garren
K C
KC
Billante
M J
MJ
Champney
M S
MS
D000818:Animals; D004285:Dogs; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004566:Electrodes; D004576:Electromyography; D007821:Laryngeal Muscles / Q000503:physiopathology; D019736:Prostheses and Implants; D014826:Vocal Cord Paralysis / Q000628:therapy*