Rehabilitation of the Paralyzed Larynx

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DESCRIPTION (provided by applicant): Functional electrical stimulation (FES) has promise as a therapy for restoring activity to a denervated muscle system. Recent studies in animals and patients have demonstrated the capacity for FES to reanimate paralyzed laryngeal abductor muscles, protect them from atrophy during regeneration, and promote selective reinnervation. In the present proposal, two lines of research, one applied and one basic, will be conducted. The overall goal of the applied research is to evaluate the capacity of FES to restore ventilation in canines with chronic bilateral laryngeal paralysis, implanted with electrical stimulation devices. In this model, the vocal fold abductor muscles will be stimulated bilaterally to reanimate glottal opening. The efficacy and safety of the device in restoring ventilation will be assessed. The overall goal of the basic research is to investigate the mechanisms by which FES facilitates reinnervation of a laryngeal muscle by its original motoneurons. Two hypotheses that could explain how FES confers neuromuscular specificity have been proposed. The first hypothesis holds that electrical stimulation maintains the motoneuron-muscle fiber specificity that was established during development, and prevents its loss upon denervation. The second hypothesis assumes that the concept of muscle plasticity extends to its synapse, and that electrical stimulation can modulate receptivity of the endplate for a particular type of motoneuron. The proposed research will distinguish between these two hypotheses. A set of related experiments will be performed to determine whether the selective effect of FES can be localized to either the nerve or muscle. Finally, with an understanding of the mechanisms for enhancing the quality of abductor muscle reinnervation, the capacity to selectively reinnervate and restore natural function in case of serious nerve lesions will be examined, to assess the clinical relevance of the approach to medicine. In general, the potential application of FES to other motor systems is limitless. With respect to the head and neck, FES could be employed initially to reanimate the unilaterally paralyzed face, larynx and pharynx, and in the process, direct natural reinnervation of these structures.