| Objective:Laryngeal dyskinesia may cause laryngeal dysfunction such as dysphonia, drinking cough, difficulty in breathing. It affects life and communication quality of patients. Severe cases can be life-threatening. Laryngeal articulation disorder etiology is complex: not only vocal cord mechanical movement disorder caused by cricoarytenoid joint dislocation and cricothyroid joint injury, but also neuromuscular dysfunction caused by recurrent laryngeal nerve and injury laryngeal nerve paralysis. Under normal condition the laryngeal joints (cricoarytenoid joint, cricothyroid joint) trajectory are still questionable. Through cadaver laryngeal arthrography, plasticizing and tissue staining, the research group find the arytenoid cartilage of cricoarytenoid joint may beat in addition to the original rotation, sliding and swing; the inferior horn of the thyroid cartilage of cricothyroid joint not only rotates but also slides in the cricoid cartilage joint fossa. The main purpose of this study are:(1) Throat CT scanning and three-dimensional reconstruction of healthy volunteers and patients are performed at two physiological states of calm breathing and "Yi" sound, respectively. They are observed whether there is sagittal movement of the arytenoid cartilage, how to quantitatively measure the sagittal displacement, whether the cricothyroid joint slides and rotates simultaneously and the movement direction. (2) The projection of muscle process in the thyroid cartilage is observed by spiral CT with 3D reconstruction technique, the preoperative laryngeal cartilage reconstruction on each patient treated is done, the hole is opened on virtual image of thyroid cartilage to operatively locate muscle process and look for optimal thyroid cartilage fenestration method. (3) Based on ultrathin plasticizing and microdissection techniques, the fine three-dimensional map of laryngeal muscles is established and the function of laryngeal muscle is investigated.Methods:1.Imaging examinationSpiral CT scanning combined with three-dimensional reconstruction of those checked are done while calm breathing and making "Yi" sound, respectively, to estimate the change of displacement and position the projection point of the muscular process of laryngeal cartilage.(1) Laryngeal thin slice volume scanning with 3D reconstruction technology was performed for 35 cases(no laryngeal diseases) and 7 patients with unilateral vocal cord paralysis while calm breathing and making "Yi" sound.(2) measurement:(a) The longitudinal displacement of the arytenoid cartilage vocal process and muscular process:The vertical distance from vocal process and muscular process of arytenoid cartilage to the scanning plane of the upper edge of cricoid arch, which was used as a reference surface, while breathing quietly and making "yi" sound, is measured respectively. And the sagittal displacement range of vocal process and muscular process of arytenoid cartilage as pronouncing is calculated.(b) Longitudinal displacement of the cartilage and the cartilage:The vertical distance from the upper edge and the lower edge of cricoid cartilage board to the scanning plane of the upper edge of the 5th cervical vertebra, which is used as a reference surface, and the vertical distance from the superior horn and inferior horn of thyroid cartilage to the reference surface, while breathing quietly and making "yi" sound, are measured respectively. The sagittal displacement range of the upper and the lower edge of the annular cartilage plate and the upper and lower corners of the cartilage plate are calculated respectively.(c) The direction of the slide of the inferior corner of the thyroid cartilage:The vertical distance from inferior horn of thyroid cartilage to the scanning plane of the upper edge of cricoid arch, which is used as a reference surface, is measured while breathing quietly and making "yi" sound, respectively. The vertical distance from inferior horn of thyroid cartilage to the coronal plane of the posterior edge of cricoid plate, which is used as a reference surface, is measured while breathing quietly and making "yi" sound, respectively. The direction of sliding is judged by reviewing the change of displacement.(d) Localization of projection point of muscular process:The distances from the projection point of muscular process on the thyroid cartilage to the superior horn and inferior horn of thyroid cartilage are measured while breathing quietly, respectively.(e) Simulation of thyroid cartilage fenestration on a 3D reconstruction image:The hole is opened forward with center at the midpoint of trailing edge of the thyroid cartilage plate and radius equal to the distance between the midpoint and the projection point of muscular process on the thyroid cartilage plate. By rotating the image, the arytenoid cartilage is explored from various perspectives.(3) statistic analysisThe experimental data were expressed as mean±tandard deviation (X±s), and the data were analyzed by SPSS 22.0 software. The mixed linear analysis and t test are performed. If P<0.05, the data has statistics difference. And the difference is statistically significant in P<0.01.2. anatomical studyUsing microsurgical anatomy combined with ultrathin sheet plastination technique, the number, trend, start and end points of laryngeal muscles (lateral cricoarytenoid muscle, thyroarytenoid muscle, cricoarytenoid posterior muscle and cricothyroid muscle), and the three-dimensional structure relationship between muscles and larynx cartilage and vocal cords are checked.(1) Transparent hard tissue block is made with cadaver throat tissue block by degreasing, dewatering and plasticizing.150-200um thick transparent slices of ultrathin plastination are produced along the horizontal, coronal and sagittal direction. Images of slices are collected and observed by microscope, HD scanner and laser confocal microscopy.(2) Laryngeal specimen is fine dissected under the stereoscopic microscope to collect the data(3) Indicators(a)To identify the relationship between the muscles of the throat.(b)To determine the distribution of the muscles of the throat(c)To locate the starting and ending points of the laryngeal muscle bundle.(d)To find the direction and angle between laryngeal muscle bundle and the reference plane.Results:1. cricoarytenoid joint:(1) Under normal physiological conditions, the sagittal displacement of vocal process of arytenoid cartilages is greater than muscle process while breathing quietly and making "yi" sound.(2) The sagittal axis displacement of muscle process and vocal process of arytenoid cartilages in different age, gender and laterality are different.(3) The vertical distance between the diseased side and the contralateral side of muscular process of patients with unilateral vocal cord paralysis is 1.5mm, and it is 0.8mm for vocal process. The vocal process and muscular process in the diseased side are higher than those in the contralateral side.(4) The muscle process and vocal process of cricoid and arytenoid cartilage can be developed properly in 3D reconstruction image.2.cricothyroid joint(1) Under normal physiological conditions, the cricoid cartilage moves relative to the cervical spine when the "yi" sound is made while the thyroid cartilage barely moves.(2) The inferior horn of thyroid cartilage slides relative to the cricoid cartilage surface while breathing quietly and making "yi" sound.3. Localization of the muscle process and the window of the thyroid cartilage plate: Throat thin slice volume scanning and three-dimensional reconstruction images can clearly show the projection of muscular process on the thyroid cartilage and 3D structure of laryngeal cartilage. Therefore, the examination should be routinely performed before laryngeal framework surgery so as to improve positioning accuracy for the muscular process. The reconstructed image can be rotated in three-dimensional direction, observed under different angles. It is allowed to open windows on the virtual Image repeatedly and design the best surgical approach4.3D construction:Lateral cricoarytenoid muscle consists of two parts, the upper part is thick, and the angle to the arch of cricoid cartilage surface is 65°. Thyroarytenoid muscle consists of two parts. One is inside and another is outside. The central lateralis thyroarytenoid muscle is thick and the angle to the reference plane is 50°. The central posterior cricoarytenoid muscle is thick and the angle to the reference plane is 40°.Conclusion:1. cricoarytenoid joint: Under normal physiological conditions, the arytenoid cartilage bounces up and down around the sagittal leaving from the cricoid cartilage articular surface besides sliding, rotating and rocking motion along the cricoid cartilage articular surface.2. cricothyroid joint: Under normal physiological conditions, the cricoid cartilage glides forward and up along the cricothyroid joint surface and rotates at the same time when the "yi" sound is made.3. Creating an accelerated method of quantitative detection of longitudinal motion of the vocal cords:Spiral CT scanning combined with three-dimensional reconstruction of those checked are done while calm breathing and making "Yi" sound, respectively, to quantitative measure bilateral vocal cord vertical position difference. The quantitative analysis of arytenoid sagittal displacement is taken as one basis for clinical assessment of vocal function.4. Positioning of laryngeal frame surgery:Throat thin slice volume scanning and three-dimensional reconstruction images can clearly show the projection of muscular process on the thyroid cartilage and 3D structure of laryngeal cartilage. Therefore, the examination should be routinely performed before laryngeal framework surgery so as to improve positioning accuracy for the muscular process. The reconstructed image can be rotated in three-dimensional direction, observed under different angles. It is allowed to open windows on the virtual Image repeatedly and design the best surgical approach 5. Three dimensional model of laryngeal muscles:The upper fasciculus of lateral cricoarytenoid muscle, the central fasciculus of lateralis thyroarytenoid muscle and the central fasciculus of posterior cricoarytenoid muscle are functional fasciculus. The pulling direction of arytenoid adduction should be set according to the direction of the laryngeal functional fasciculus. |
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