先天性耳道狭窄不伴听骨畸形患者听力和CT影像学研究

Exploration of hearing function and CT images in patients with congenital aural stenosis without ossicle malformations

目的比较正常耳和先天性耳道狭窄不伴听骨畸形患者听力和颞骨解剖参数,探讨此类患者纯音测听气骨导差形成的病理生理学机制。方法回顾分析20例正常耳和15例先天性耳道狭窄不伴听骨畸形患者的纯音测听和颞骨CT数据,将两组CT序列图像导入Mimics软件,在三维重建的基础上读取解剖标志点。通过Matlab软件编制程序,计算并比较健康对照组和耳道狭窄组的鼓环前后径和上下径、镫骨底板前后径和上下径、鼓环面积、鼓膜面积、镫骨底板面积、鼓膜前后方向开角及上下方向开角。结果耳道狭窄组的气骨导差为(26±7)dB,健康对照组为(6±2)dB,两组差异有统计学意义(P<0.05)。耳道狭窄组与健康对照组的鼓环前后径[(5.30±1.25)mm vs(8.89±0.67)mm]和上下径[(7.77±1.88)mm vs(10.60±0.60)mm]、鼓环面积[(32.78±8.68)mm^(2) vs(72.57±6.36)mm^(2)]、鼓膜前后方向开角[(90.99±22.86)°vs(124.05±18.88)°]和上下方向开角[(114.01±29.23)°vs(139.83±11.04)°]、鼓膜面积[(40.33±10.55)mm^(2) vs(75.67±7.03)mm^(2)]以及鼓膜/镫骨底板面积比值[(10.03±4.07)vs(17.96±3.16)]的差异均有统计学意义(P<0.05)。结论先天性耳道狭窄患者的鼓膜/镫骨底板面积比值较正常耳小,患耳无法通过鼓膜/镫骨底板比值的水力学作用放大声压,这可能是不伴听骨畸形耳道狭窄患者的纯音测听气骨导差较正常耳大的主要原因。此外,由于解剖参数的差异,对于先天性耳道狭窄患者,应在术前行CT影像学评估。

Objective To compare the pure tone audiometry and anatomical parameters of the middle ear between normal ears and the ears with congenital aural stenosis without ossicle malformations and to explore the formation of air-bone gap.Methods The pure tone audiometry and temporal bone computer tomography(CT)data of 20 cases with normal ears and 15 cases with congenital ear canal stenosis without ossicle malformations were analyzed retrospectively.The CT sequence images of the two groups were imported into Mimics software,and the anatomical landmarks were read based on 3D reconstruction.Matlab software was used to calculate and compare the diameters of drum ring,the diameters of stapes footplate,the area of drum ring,the area of tympanum,the area of stapes footplate,the opening angle of tympanum in the front and back direction and the opening angle in the upper and lower direction in the normal group and the stenosis group.Results The air-bone gap was(26±7)dB in the stenosis group and(6±2)dB in normal group,and the difference was statistically significant(P<0.05).In the stenosis group and the normal group,the anterior and posterior diameter of the drum ring was(5.30±1.25)mm vs(8.89±0.67)mm,the upper and lower diameter of the drum ring was(7.77±1.88)mm vs(10.60±0.60)mm,the area of the drum ring was(32.78±8.68)mm^(2) vs(72.57±6.36)mm^(2),the anterior and posterior open angle of the drum ring was(90.99±22.86)°vs(124.05±18.88)°,and the upper and lower opening angle was(114.01±29.23)°vs(139.83±11.04)°respectively.The tympanum area was(40.33±10.55)mm^(2) vs(75.67±7.03)mm^(2) and the ratio of tympanum area to stapes footplate area was(10.03±4.07)vs(17.96±3.16).There were statistically significant differences in the anatomic parameters mentioned above between the stenosis group and normal group(P<0.05),but there were no significant differences in the diameters or area of stapes footplate(P>0.05).Conclusions Compared with the normal group,the area ratio of tympanic membrane to stapes footplate was smaller in the stenosis group without ossicle malformations.Therefore,the ear with aural stenosis could not amplify sound pressure efficiently through the hydraulic effect of the ratio of tympanic membrane to stapes footplate.As a result,the air-bone gap of pure tone audiometry in the stenosis group was larger than that in the normal group.In addition,due to the above differences in anatomical parameters,CT image evaluation is required for patients with congenital aural stenosis before surgeries.