蜗神经发育不良患儿蜗神经及听皮层功能的研究

Cochlear nerve deficiency (CND) refers to a small or absent cochlear nerve as revealed by the results of magnetic resonance imaging. Cochlear implantation (CI) has been used as a treatment option for children with CND. The outcomes of CI in children with CND were worse than those in children with normal cochlear nerve, and varied among these patients. To date, the neurophysiological mechanisms underlying inter-patient variations after CI in implanted children with CND are not well understood. There is still no efficient clinical tool to predict CI outcomes for CND children. Our previous work showed that CND children need higher stimulus charge to evoke neural response. Furthermore, the responsiveness of electrically stimulated cochlear nerve reduced as the stimulating site moved from the basal to the apical end of the cochlea. However, the ability of cochlear nerve to encode sound information has not been deciphered. Therefore, the present study was designed to: 1) test the deterioration of cochlear nerve function among CND children; 2) determine the distribution of survival spiral ganglion cells along the cochlea; 3) investigate the ability of encoding temporal and spectral information of cochlear nerve and auditory cortex; 4) analyze the effect of cochlear implantation parameters on the outcomes of CI in children with CND.

蜗神经发育不良（CND）是指蜗神经发育较细或未发育。人工耳蜗植入技术对CND患儿有效，但其耳蜗术后效果较蜗神经发育正常患儿差，且患儿个体间差异较大。目前，导致CND患儿耳蜗术后的个体差异性的神经生理学机制尚不明确，临床上尚无可靠的方法来预估CND患儿耳蜗术后效果。课题组前期研究发现CND患儿需要较大的刺激电量才能记录到电极周围的神经反应，且CND患儿蜗神经对电刺激的反应由耳蜗底转至耳蜗顶转逐渐减弱。然而，CND患儿蜗神经对声音信号的编码能力尚不清楚。本项目组在前期研究的基础上，拟采用客观方法研究CND患儿蜗神经的损伤程度及残存螺旋神经节细胞在耳蜗内的分布；分别从蜗神经水平及听皮层水平研究CND患儿耳蜗不同部位蜗神经对时域信息及频率信息的编码能力；并探讨是否可以依据蜗神经及听皮层对电刺激的反应来优化耳蜗程序中使用的参数来提高耳蜗术后效果。

研究背景 人工耳蜗（Cochlear Implant，CI）植入是治疗重度极重度感音神经性耳聋的最有效方法，但仍有部分患者治疗效果不佳，蜗神经发育不良( Cochlear Nerve Deficiency, CND)就是其中最重要的原因之一。目前临床上尚无有效且可靠的手段在术前预估CND患者的CI术后效果。如何在CI术后充分利用耳蜗内残余的螺旋神经节细胞的功能，进而提高CND患者CI植入术后效果是困扰临床医生的难题。.主要研究内容 首先，采用Customer Sound EP软件记录所有电极周围的电刺激复合动作电位（ECAP），并记录耳蜗不同部位电极的ECAP增益曲线。从而分析CND患者与蜗神经形态正常患者ECAP引出率、ECAP诱发阈值、ECAP最大振幅、ECAP增益曲线坡度等之间的差异。其次，分析CND患者影像学检查听神经直径、蜗神经管宽度等结果与蜗神经功能之间的相关性。再次，分析了CND患者术后助听听阈、听觉能力评分（CAP）、言语可懂度评分（SIR）及言语识别率的进展情况。.重要结果 与蜗神经形态正常SNHL患者相比，CND患者ECAP引出率降低， ECAP诱发阈值显著提高、ECAP最大振幅显著降低、AGF坡度显著减小、ECAP潜伏期显著延长。CND患者蜗神经对电刺激的反应由耳蜗底转至耳蜗顶转呈逐渐降低趋势。CND患者术前影像学检查结果与ECAP测试结果无明显相关性。CND患者CI术后听觉与言语能力显著提高，但其进展速度较慢且比蜗神经形态正常SNHL差。.科学意义 与蜗神经形态正常SNHL患者相比，CND患者不仅残余螺旋神经节细胞的数量减少，且螺旋神经节细胞的功能也受损。CND患者蜗神经损伤程度个体间差异较大。总体上，CND患者蜗神经的损伤程度由耳蜗底转至耳蜗顶转呈逐渐加重趋势。