Determination of the optimal conditions for laryngeal pacing with the Itrel II implantable stimulator

OBJECTIVE: To determine the optimal stimulus paradigm, electrode orientatio n, and configuration of an implantable stimulator used to reanimate the pos terior-cricoarytenoid (PCA) muscle in case of bilateral vocal fold paralysi s (BVFP). STUDY DESIGN: Acute studies were conducted on 13 canines implanted with Itr el II systems with or without PCA innervation. PCA stimulus-response charac teristics were obtained by measuring stimulated vocal fold displacement end oscopically. RESULTS: The denervated PCA was only 10% to 25% as responsive to stimulatio n as the innervated PCA. However, the response could be increased to 38% an d 61% if the Itrel was modified to deliver 1 and 2 msec pulses, respectivel y. Stimuli delivered centrally to the muscle 5 mm from the median raphe imp roved performance. CONCLUSION AND SIGNIFICANCE: The optimal stimulus paradigm identified in th is study (I msec pulses delivered at 30 to 40 Hz and 2 to 8.5 mA) has been applied to implanted BVFP patients and improved outcome. Information regard ing optimal electrode orientation could also be important to future clinica l trials.