EFFECTS OF VAGAL NERVE-STIMULATION ON LARYNGEAL FUNCTION

Functional electrical stimulation is a developing methodology that sho ws significant potential in the management of peripheral neuromuscular deficits. Potential applications in the head and neck area, including control of bilateral vocal fold paralysis and spasmodic dysphonia, ha ve recently been explored. Despite promising early results, very littl e is known about the mechanisms of action or the long-term effects of electrical stimulation on human laryngeal function. Recent development of implantable vagal nerve stimulators as a method to control intract able seizures in individuals who have not responded to medication prov ides a unique opportunity to study its effect on the normal human lary nx. Laryngeal and vocal function testing was studied on five individua ls who had undergone vagal nerve stimulator implants for intractable s eizures. Consistent abduction/adduction of the left vocal fold was ach ieved at 20 and 40 Hz, respectively. Higher levels of electrical stimu lation produced hemispasm of the larynx. Results were consistent with studies in the literature of recurrent laryngeal nerve stimulation in animal and human models. The vagus nerve provides relatively easy acce ss for implantation of electrodes to provide electrical stimulation to the muscles of the larynx. Vagal nerve stimulation may prove efficaci ous in the treatment of movement disorders of the larynx; further stud y is needed.