The effects of chronic electrical stimulation on laryngeal muscle physiology and histochemistry.

The present study examined the effects of functional neuromuscular stimulation (FNS) on posterior cricoarytenoid (PCA) muscle physiology and histochemistry. In 4 canines, 10 cm of the recurrent laryngeal nerve was resected. A patch electrode array was implanted for PCA stimulation. FNS was applied to 2 canines for a period of 4 weeks with 2 additional animals serving as nonstimulated controls. Results indicated that FNS increased PCA muscle contractility over the period of intervention but had no effect on contraction speed. FNS also protected the muscle from atrophy by preventing muscle weight loss and type 2 fiber deterioration. Finally, it rescued muscle fibers from ensuing fibrosis.

Zealear DL ，Billante CR ，Chongkolwatana C ，Rho YS ，Hamdan AL ，Herzon GD ... -  《ORL-Journal for Oto-Rhino-Laryngology Head and Neck Surgery》

The effects of chronic electrical stimulation on laryngeal muscle reinnervation.

The present study examined the effects of functional neuromuscular stimulation (FNS) on reinnervation of the posterior cricoarytenoid (PCA) muscle. In 4 canines, the recurrent laryngeal nerve (RLN) was sectioned and anastomosed and a patch electrode array implanted for stimulation and recording at multiple PCA sites. Following implantation, FNS was applied to 2 canines for a period of 6 weeks. Two additional animals served as nonstimulated controls. In each animal, histomorphometric analysis of the RLN was used to assess the quality of nerve regeneration and the potential for muscle reconnection. The magnitude of reinnervation was monitored by electromyographic (EMG) potentials evoked by RLN stimulation. The appropriateness of reconnection was determined by the pattern of spontaneous EMG activity and recovery of vocal fold abduction. Results of this preliminary study indicated that FNS caused an overall repression of reinnervation. However, the repression preferentially inhibited reconnection by foreign nerve fibers, promoting selective reinnervation and preventing synkinesis.

Zealear DL ，Billante CL ，Chongkolwatana C ，Herzon GD ... -  《ORL-Journal for Oto-Rhino-Laryngology Head and Neck Surgery》

Reinnervation of the canine posterior cricoarytenoid muscle with sympathetic preganglionic neurons.

Jacobs IN ，Sanders I ，Wu BL ，Biller HF ... -  《ANNALS OF OTOLOGY RHINOLOGY AND LARYNGOLOGY》

Effects of denervation on posterior cricoarytenoid muscle physiology and histochemistry.

Zealear DL ，Hamdan AL ，Rainey CL 《-》

Stimulation of denervated muscle promotes selective reinnervation, prevents synkinesis, and restores function.

Previously, electrical stimulation of denervated canine laryngeal muscle was shown to promote reinnervation by native over foreign motoneurons. The goal of this study was to assess the effect of different stimulus paradigms on reinnervation quality and functional recovery. A prospective study of six canines over 8 to 20 months. A clinical model of laryngeal paralysis was used, where recurrent laryngeal nerves of the animals were sectioned and ventilation compromised. The abductor, posterior cricoarytenoid (PCA) muscles were implanted bilaterally with electrodes from an implantable pulse generator. Animals were randomly assigned to three groups to assess the effect of different stimulus paradigms: 1) 40 pulses per second (pps) train, 2) 10 pps train, 3) no stimulation. Spontaneous vocal fold movement was measured endoscopically during hypercapnia. Exercise tolerance was measured on a treadmill using pulse oximetry. In the terminal session, electromyography (EMG) potentials were recorded during superior laryngeal nerve stimulation to index foreign reinnervation of the PCA by reflex glottic closure (RGC) motoneurons. After reinnervation started, nonstimulated and stimulated 40 pps animals displayed paradoxical closure of the glottis during hypercapnia and severely decreased exercise tolerance due to faulty reinnervation. In contrast, stimulated 10 pps animals displayed minimal paradoxical closure and normal exercise tolerance (12 minutes up to 8 mph). EMG findings in this group demonstrated significantly less PCA reinnervation by foreign RGC motoneurons. PCA stimulation with low frequency reduced synkinetic reinnervation by foreign RGC motoneurons. Paradoxical closure of the glottis with inspiration was reduced and exercise tolerance restored to normal.

Zealear DL ，Mainthia R ，Li Y ，Kunibe I ，Katada A ，Billante C ，Nomura K ... -  《-》