The Morphological Observation Of Recurrent Laryngeal Nerve And Posterior Cricoarytenoid Muscle In Patients With Idiopathic Vocal Fold Paralysis

Objectives:Through the observation of laryngeal recurrent nerve, posterior cricoarytenoid muscle and motor end plate in patients with idiopathic vocal cord paralysis, to investigate whether there is existence of tissue basis for recurrent laryngeal nerve regeneration in idiopathic vocal fold paralysis。Methods:During the period from 2014 February to 2015 February in our department,17 cases of idiopathic vocal cord paralysis were included in this study. The inclusion criteria is for vocal cord paralysis patients demonstrated by the preoperative dynamic stroboscopy, eliminating head and neck, chest, mediastinal tumor and cerebrovascular diseases, receiving conservative treatment of over 6 months while sound had no improvement or not obvious, voluntarily accepting arytenoid adduction combined with recurrent laryngeal nerve repair surgery. The course is divided into three groups: ① 0.5-1 years group (3 male,3 female, age 42.0+19.96 years); ②> 1-2 years group (1 male,4 female, age 50.60 ± 14.67 years). ③> 2 years group (3 male,3 female, age 35.33 ±11.37 years old). Normal laryngeal nerve and posterior cricoarytenoid muscle (from laryngeal cancer patients with total laryngectomy) as normal control group. Take the,, damaged side recurrent laryngeal nerve (11 cases), toluidine blue staining, light microscope to observe the number of myelinated nerve fiber in laryngeal recurrent nerve, electron microscope was used to observe the laryngeal recurrent nerve demyelination and ultrastructure changes. Take part of the posterior cricoarytenoid muscle (17 cases), the Masson trichrome staining, using image pro plus system to analysis two indicators of relative cross-sectional area of the muscle fibers,relative cross-sectional area of collagen fibers. Posterior cricoarytenoid muscles (10 cases), acetylcholinesterase staining, to observe the number and morphology observation of motor end plates. The experimental data were statistically analyzed with SPSS 18.0(P<0.05, the difference was statistically significant).Results:1.The tissue morphological observation of recurrent laryngeal nerve in idiopathic vocal cord paralysisLight microscope showed that with the extension of the duration of the disease, there is a gradual decrease in the number of myelinated nerve fiber in recurrent laryngeal nerve.Electron microscope showed a larger descrement of the thick myelinated nerve fibers (nerve fiber diameter), demyelination degree of recurrent laryngeal nerve were gradually aggravated with the duration prolonging, the performance for myelin swelling and vacuolization, cell density, myelin sheath layer release shedding and a large number of Bungner distribution. With the exception of 2 cases, case 1, although course is very short, only for half a year, but recurrent laryngeal nerve severe demyelination, a substantial reduction in myelinated nerve fibers and case 6, although for up to 4 years, light microscope and electron microscope, laryngeal recurrent nerve has no obvious demyelination, there still was large number of thick myelinated nerve fibers and thin myelinated nerve fibers. Prompt nerve injury and the course of idiopathic vocal cord paralysis have a certain relationship, but there are great individual differences in nerve damage.2. The observation of posterior cricoarytenoid muscle morphological in idiopathic vocal fold paralysisAlong with the extension of the duration of the disease, idiopathic vocal cord paralysis ring posterior cricoarytenoid muscle fiber cross-sectional area decreases gradually, and collagen fiber area gradually increased. Muscle/collagen cross-sectional area ratio decreased gradually,0.5-1 year group than in the normal control group decreased 75.14%> 1-2 years group than 0.5-1 year group decreased 52.68%> 2 years more than 1-2 years group fell 18.63%. Idiopathic vocal cord paralysis with each ring posterior cricoarytenoid muscle relative muscle cross-sectional area and collagen relative cross-sectional area and normal control group differences were statistically significant (P< 0.05),0.5-1 year group and> 1-2 years group and> 2 years group difference has statistical significance (P< 0.05) and> 2 years group and> 1-2 years between group difference no statistical significance. The same course subgroup of idiopathic vocal cord paralysis ring posterior cricoarytenoid muscle and subject group pre traumatic paralysis of vocal cord ring posterior cricoarytenoid muscle research data are compared, differences between subgroups of the two had no statistical significance (P> 0.05). But idiopathic vocal cord paralysis group in some cases, although duration up to 10 years, but the central posterior cricoarytenoid muscle atrophy fibrosis is not serious, and in some cases course although only 1.5 years, but muscle atrophy is very obvious, suggesting idiopathic vocal cord paralysis ring posterior cricoarytenoid muscle atrophy fibrosis degree and duration of disease related, but there are also individual differences.3.The observation of posterior cricoarytenoid muscle motor endplate in idiopathic vocal fold paralysisWithin duration of 2 years, there are still a large number of motor endplates on posterior cricoarytenoid muscle, motor endplate structure is clear, forming motor endplate bands in the central part of the muscle, and muscle fibers are almost vertical and almost normal morphology and especially for 0.5-1 years, motor endplates in morphologically intact,1-2 years although there are a certain number of motor endplates, but irregular shape, pyknosis and small, the edge is not clear. While the duration of more than 2 years,muscle motor endplate is very rare, sporadic scattered in a small number of motor endplates in the presence of remaining of the muscle fiber surface.Conclusion:With the duration of the extension of idiopathic vocal fold paralysis, recurrent laryngeal nerve demyelination degree gradually increased and the number of myelinated nerve fiber decreased gradually, but there are special cases need large sample count for statistical analysis, ring posterior cricoarytenoid muscle atrophy fibrosis aggravated gradually, motor end plate number gradually decreased and morphologic abnormality, but there are special cases, the pathological change extent and duration of the disease are not consistent. Duration 1-2 years is recurrent laryngeal nerve, posterior cricoarytenoid muscle and motor end plate tissue morphology change the most obvious stage, less than 2 years duration still exist good nerve, muscle morphology and movement of the endplate morphology, tip during larynx return nerve repair can achieve the ideal effect, but there are individual differences.