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

OBJECTIVE: To determine the optimal stimulus paradigm, electrode orientation, and configuration of an implantable stimulator used to reanimate the posterior-cricoarytenoid (PCA) muscle in case of bilateral vocal fold paralysis (BVFP). STUDY DESIGN: Acute studies were conducted on 13 canines implanted with Itrel II systems with or without PCA innervation. PCA stimulus-response characteristics were obtained by measuring stimulated vocal fold displacement endoscopically. RESULTS: The denervated PCA was only 10% to 25% as responsive to stimulation as the innervated PCA. However, the response could be increased to 38% and 61% if the Itrel was modified to deliver 1 and 2 msec pulses, respectively. Stimuli delivered centrally to the muscle 5 mm from the median raphe improved performance. CONCLUSION AND SIGNIFICANCE: The optimal stimulus paradigm identified in this study (1 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 regarding optimal electrode orientation could also be important to future clinical trials.

The biocompatibility, integrity, and positional stability of an injectable microstimulator for reanimation of the paralyzed larynx.

The biocompatibility, integrity, positional stability, and potential use of hermetically sealed injectable wireless micromachined microstimulators were investigated for reanimation of the paralyzed larynx. The device, consisting of silicon and glass, has been tested and proven to be biocompatible with no evidence of pathological tissue reaction or rejection up to one-year implantation in the rat dorsum and canine larynx. By one month, each unit was encapsulated by a thin membrane, which thickened to form a fibrous layer of less than 500 microm at 6-12 months. The microstimulators demonstrated long-term in vivo durability: the hermetic seal of only one in ten devices was breached. Once implanted, migration of the device varied from 0 to 3 cm, depending upon the extent of surgical dissection. No discernable migration was noted when the tissue dissection was minimal. Studies utilizing a modified device equipped with electrodes indicated that migration was nominal with sufficient positional stability to ensure activation of target muscles for glottis opening. This study supported the feasibility of using a microstimulator for reanimation of paralyzed laryngeal muscles that open the airway during breathing. This innovative approach to treatment would alleviate the need for a tracheotomy or surgical resection of the vocal fold.

Post-varicella epiglottitis and necrotizing fasciitis.

Varicella is a nearly ubiquitous acquired childhood disease. Infectious complications of varicella can be life- or limb-threatening. These complications appear 3 to 4 days after the appearance of varicella exanthem and are heralded by fever, pain, and erythema of the overlying skin. Airway complications of varicella are rare, rapidly evolving, and, unfortunately, difficult to visualize. We report a child who presented with a unique combination of varicella-induced airway complications-acute epiglottitis and subsequent necrotizing fasciitis of the head and neck. varicella, epiglottitis, necrotizing fasciitis, group A beta-hemolytic streptococcus, nasopharyngoscopy.