ELECTRONIC INTEGRATION OF GLOTTIC CLOSURE AND CRICOPHARYNGEAL RELAXATION FOR THE CONTROL OF ASPIRATION - A CANINE STUDY

Aspiration can result from muscular weakness or paralysis of laryngoph aryngeal muscles after lower motor neuron disorders (e.g., stroke) or unchecked gastroesophageal reflux, We submit that rehabilitation of th e finely tuned swallowing mechanism should provide at least restoratio n of the normal dynamic relationships between glottic closure and cric opharyngeal relaxation. In three dogs under general endotracheal anest hesia, the recurrent laryngeal nerves and the pharyngeal musculature w ere exposed through a midline cervical incision. A tracheotomy was per formed to allow unhindered laryngoscopic exposure of the vocal cords. A no. 9 endotracheal tube passed through the upper esophageal sphincte r was used as a pressure transducer by saline inflation of its cuff an d linked to an oscilloscope. The cricopharyngeus was placed under base line tension with pulse trains administered by an intramuscular needle electrode with a circuit previously used for agonist/antagonist coupl ing of reinnervated facial musculature. A second output channel was li nked to the contralateral recurrent laryngeal nerve by a bipolar elect rode, As the pulse width of the current to the recurrent laryngeal ner ve increased, that to the cricopharyngeus was reciprocally decreased, producing snug glottic closure and synchronous cricopharyngeal relaxat ion, Results were documented on videotape, These findings were highly reproducible. We believe that the novel approach proposed in the curre nt model offers an attractive solution to long-term aspiration problem s resulting from an imbalance between vocal cord and cricopharyngeal a ctivities.