典型中耳病变对圆窗激振听力补偿性能影响的数值分析

Numerical analysis on sound compensation performance of round window stimulation in typical middle ear diseases

目的研究典型中耳病变对圆窗激振听力补偿效果的影响,为圆窗激振式人工中耳的优化设计提供参考。方法利用CT扫描和逆向成型技术建立包括中耳和耳蜗的有限元模型,并验证模型的可靠性。再基于该模型,通过改变相应组织的材料属性,分别模拟镫骨环韧带硬化、镫骨不正常发育和锤骨前韧带硬化3种典型中耳病变。通过对比相应的基底膜响应,分析这3种病变对圆窗激振听力补偿效果的影响。结果镫骨不正常发育主要在高频处降低圆窗激振的效果,镫骨环韧带硬化和锤骨前韧带硬化主要恶化圆窗激振低频段的响应。3种病变中,镫骨环韧带硬化对圆窗激振听力补偿效果影响较大,等效声压的减小量可高达17 d B。结论中耳病变恶化圆窗激振的听力补偿效果,且恶化量较大,故在设计圆窗激振式人工中耳时需要针对性地提高其作动器的输出量。

Objective To study the effect of typical middle ear diseases on sound compensation of round window（RW） stimulation,so as to provide references for the optimal design of middle ear implants by RW stimulation.Methods The finite element model of the middle ear and cochlea was built by CT scanning and reverse engineering technique,and its reliability was also verified.On the basis of the model and by changing material properties of corresponding tissues,three typical middle ear diseases were simulated：hardening of stapedial annular ligament,abnormal stapedial bone growth and hardening of anterior mallear ligament.Then the response from displacement of basilar membrane（BM） was compared to analyze the impact of this 3 types of middle ear diseases on sound compensation of RW stimulation.Results The stapes with abnormal bone growth severely deteriorated the equivalent sound pressure（ESP） of RW stimulation at higher frequencies,while the hardening of stapedial annular ligament and the hardening of anterior mallear ligament prominently decreased ESP of RW stimulation at lower frequencies.Among the 3 types of middle ear diseases,hardening of stapedial annular ligament affected the sound compensation of RW stimulation more significantly with the amount of the ESP reduction up to 17 d B.Conclusions Middle ear diseases can deteriorate the sound compensation of RW stimulation seriously with large deterioration,Therefore,the output of the actuator should be targeted to improve when designing the middle ear implants by RW stimulation.