Quantitative Assessment of Laryngeal Muscle Morphology After Recurrent Laryngeal Nerve Injury: Right vs. Left Differences

Abstract

Reports of laryngeal response to denervation are inconsistent. Some document atrophy and fibrosis in denervated laryngeal muscles, whereas others indicate resistance to atrophy. Spontaneous reinnervation has also been documented. The goal of this study was to clarify the effects of nerve injury and reinnervation on thyroarytenoid (TA) and posterior cricoarytenoid (PCA) muscles. Laboratory experiment. TA and PCA muscles of cats were harvested 5 to 6 months after transecting right or left recurrent laryngeal nerve (RLN). Images of muscle cross-sections were acquired and studied using an image analysis workstation. Cross-sectional areas as well as total cross-sectional area of randomly selected muscle fibers were recorded. TA reinnervation was robust on both sides, but there was less reinnervation of the PCA muscle after left-sided RLN lesion than after right-sided injury. Differences in reinnervation after RLN injury could contribute to the higher clinical incidence of left- vs. right-sided laryngeal paralysis.