Morphologic Correlates for Laryngeal Reinnervation

OBJECTIVE: To describe morphologic correlates for laryngeal reinnervation. STUDY DESIGN: Review of anatomic experiments dealing with laryngeal innervation performed over a 25-year period. METHODS: Description of results from experimental studies on the cat and human laryngeal muscles and nerve supply. RESULTS: Despite separation of abductor and adductor laryngeal motor neurons in the central nervous system, the mixture of abductor and adductor axons in the recurrent laryngeal nerve indicates that selective re-innervation of an individual laryngeal muscle must be accomplished at the neuromuscular junction (NMJ) of the muscle. The optimal time for a reinnervating neural source to re-occupy vacated NMJ is at the time of denervation. If the reinnervation procedure is attempted long (>1 mo) after denervation, extraneous end plates of other neural systems must be eliminated to provide vacant NMJ. The nerve muscle pedicle (NMP) concept is an effective model for reinnervation of a laryngeal muscle provided its activity pattern is similar to that of the denervated muscle and its insertion into vacated NMJ is timely. CONCLUSION: NMP offers a logical method for selective laryngeal muscle reinnervation. Critical to the success of NMP are the physiological input to the NMP and timing of NMP implantation.