Effects of Functional Electrical Stimulation on Denervated Laryngeal Muscle in a Large Animal Model

Abstract

week denervation period, the PCA was stimulated using a once daily training session for 29 eight weeks in seven animals. Three animals were used as unstimulated controls. 30Denervation produced a significant increase in rheobase (p<0.001). Electrical stimulation 31 produced a 30% increase in fiber diameter in comparison with the unstimulated control 32 group (33.9 ±2.6um FES+ , 23.6 ±4.2um FES -, p=0.04). A trend towards a decrease in 33 the proportion of type 1 (slow) fibers and an increase in type 2a (fast) fibers was also 34 observed. Despite these changes improvement in PCA function at rest was not observed. 35These data suggest that electrical stimulation using a relatively conservative set of 36 stimulation parameters can reverse the muscle fiber atrophy produced by complete 37 denervation while avoiding a shift to a slow (type 1) fiber type. 38 39 3 Introduction 40

Functional electrical stimulation following nerve injury in a large animal model

“…Myosin heavy chain gene expression is influenced by innervation, with upregulation of type IIx genes in denervated muscles and complete loss of type I fiber from the PCA muscle after RLn transection . This dependence of fiber type expression upon neural input is also evident in the equine PCA that shows an increase in type IIx fibers after complete denervation and a marked reduction in type I fiber after progressive denervation induced by idiopathic recurrent laryngeal neuropathy . The specific morphometric changes of laryngeal muscles after denervation and reinnervation seem to be species‐specific, with a reduction of type I fibers in rats and an increase in dogs .…”

“…Following euthanasia, the right PCA and LCA muscles were isolated and mid‐body transverse sections embedded in cutting medium (Tissue‐Tek OCT Compound, Sakura Finetek, Netherlands) and frozen in melting isopentane precooled in liquid nitrogen (‐156°C). Thereafter, 7 μm cryosections were air‐dried onto glass slides and stored at −80°C and processed as previously described . All mature skeletal muscle fiber types (I, IIa and IIx), hybrid fibers and collagen V were identified in single cryosections using a multiple immunofluorescence labelling technique with 4 different primary antibodies .…”

“…Breathing phases during exercise were identified using synchronized airway pressure traces overlying the video recordings. The degree of arytenoid abduction was measured as previously described . MFD obtained for each fiber type within each muscle were allocated into 5 μm bins and plotted as histogram envelopes.…”

Reversing Age Related Changes of the Laryngeal Muscles by Chronic Electrostimulation of the Recurrent Laryngeal Nerve

“…In addition, the targeted muscle was different (PCAM instead of TAM) and frequently an intervention with acute RLN injury/denervation was made. Most of these studies showed promising results in terms of restoring abductory movement of the VF, improving ventilation parameters, and demonstrating the safety of the intervention [30]. However, choosing the right stimulation parameters, and the daily pattern of stimulation sessions requires considerable care and further research.…”

Functional Electrical Stimulation Leads to Increased Volume of the Aged Thyroarytenoid Muscle

“…FES has proven to be a possible upcoming treatment option for bilateral vocal fold paralysis, and it remains to elucidate if the anatomical site used for stimulation in this trial is a reasonable approach to restore muscle mass in, for example, unilateral vocal fold paralysis in humans . Additionally, this surgical approach did not change the anatomical structures of the larynx in contrast to existing methods (e.g., thyroplasty).…”