Artificial voice modulation in dogs by recurrent laryngeal nerve stimulation: electrophysiological confirmation of anatomic data.
OBJECTIVE
We hypothesized that voice may be artificially manipulated to ameliorate dystonias considered to be a failure in dynamic integration between competing neuromuscular systems.


METHODS
Orderly intrinsic laryngeal muscle recruitment by anodal block via the recurrent laryngeal and vagus nerves has allowed us to define specific values based on differential excitabilities, but has precluded voice fluency because of focused breaks during stimulation and the need to treat several neural conduits. Such problems may be obviated by a circuit capable of stimulating some axons while simultaneously blocking others in the recurrent laryngeal nerve, which carries innervation to all intrinsic laryngeal muscles, including the arguably intrinsic cricothyroideus. In 5 dogs, both recurrent laryngeal nerves received 40-Hz quasi-trapezoidal pulses (0 to 2000 microA, 0 to 2000 micros, 0 to 500 micros decay) via tripolar electrodes. Electromyograms were matched with audio intensities and fundamental frequencies recorded under a constant flow of humidified air. Data were digitized and evaluated for potential correlations.


RESULTS
Orderly recruitment of the thyroarytenoideus, posterior cricoarytenoideus, and cricothyroideus was correlated with stimulating intensities (p < .001), and posterior cricoarytenoideus opposition to the thyroarytenoideus and cricothyroideus was instrumental in manipulating audio intensities and fundamental frequencies.


CONCLUSIONS
Manipulation of canine voice parameters appears feasible via the sole recurrent laryngeal nerve within appropriate stimulation envelopes, and offers promise in human laryngeal dystonias.
Broniatowski
Michael
M
Department of Surgery (Otolaryngology-Head and Neck Surgery), Saint Vincent Charity Hospital, University Hospitals Health System, USA.
Grundfest-Broniatowski
Sharon
S
Tucker
Harvey M
HM
Tyler
Dustin J
DJ
D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D004576:Electromyography; D005240:Feasibility Studies; D007821:Laryngeal Muscles / Q000294:innervation* / Q000502:physiology; D007830:Larynx / Q000033:anatomy & histology* / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D012009:Recurrent Laryngeal Nerve / Q000033:anatomy & histology / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology; D014831:Voice / Q000502:physiology*