声带下方收敛角度在声门闭合不全发声困难中可能的作用机理

摘要

目的 探讨喉三维CT重建下声带下方收敛角度的测量方法,探索声门闭合不全对声带下方收敛角度的影响,分析声门闭合不全发声疲劳可能的气流动力学原因.方法 采用双源薄层CT,嘱受试者发/i:/音时扫描10例正常人的20侧声带(声门闭合组),深吸气时扫描8例单侧声带麻痹患者的麻痹侧声带(声门闭合不全组),经深吸气时扫描另10例正常人的20侧声带(声带外展组);导入影像数据于Mimics软件,构建声带及气道的3D模型,联合这两模型测量声带下方收敛角度;采用单因素方差分析,比较3组受试者声带下方收敛角度的差异;并尝试采用材料的斜截面应力分配原理进行声门下压力分析,探讨声门下收敛角度对启动发声时声带振动可能的影响.结果 声门闭合组、声门闭合不全组及声带外展组的声带下方收敛角度分别为33.49°±3.75°、55.03°±2.61°及75.02°±7.32°,三组间差异有统计学意义(P<0.01),声带下方收敛角度随声门闭合不全程度增加而增加.结论 声带下方收敛角度可以通过声带及气道的3D模型进行有效测量,声门闭合不全程度增加会引起该角度增大,可能会导致声门下压力作用于声带下方的剪切力和正应力的分力发生变化,从而引起发声困难.%Objective To study the effect of sub-glottal convergence angle on the degree of glottal closure, and to analyze the potential mechanism of dysphonia by the incomplete glottal closure.Methods Three vocal fold positions (adduction, intermediate and abduction) were evaluated by the degree of glottal closure, and divided into three groups.The neck CT images of the subjects were gathered.The vocal folds were adduction group when the normal subjects made a sustaining phonation /i:/ during CT scanning;the vocal folds were abduction group when the normal subjects made a deep breathing during CT scanning, and the unilateral vocal folds were incomplete closing group when the unilateral vocal fold paralysis subjects made a deep breathing during CT scanning.3D models of the vocal folds and the airway were reconstructed using Mimics software, through which the sub-glottal convergence angle was measured.Using one-way factor analysis of variance, we compared the angle among three groups.Results The angle changed with degree of glottal closure, with statistically significant differences among the three groups(P<0.01).The means of the angle in three groups were 33.49°±3.75°, 55.03°±2.61° and 75.02°±7.32°.Conclusion The 3D model generation from CT data is an effective method of measuring the sub-glottal convergence angle, while the angle changes with the degree of glottis closure.The angle may affect sub-glottal pressure distribution in the sub-glottal shear or normal direction and influence vocal fold vibration, which would make vibration and vocal fold mucosal wave generation more difficult, and might cause dysphonia.