蜗神经发育不良患者蜗神经对电刺激反应特点的研究

Characteristics of responsiveness of cochlear nerve to electrical stimulation in patients with cochlear nerve deficiency

目的观察蜗神经发育不良(cochlear nerve deficiency,CND)患者人工耳蜗植入后蜗神经对电刺激的反应,并比较其与蜗神经形态正常植入者之间的差异,探讨CND患者蜗神经损伤特点。方法研究对象为2012年1月至2020年1月在山东省耳鼻喉医院接受人工耳蜗植入的患者,分为CND组及对照组。CND组51例,其中男20例、女31例,CI植入年龄(2.7±1.5)岁,4例双侧植入,共计55耳,术前均经影像学检查诊断为CND,其耳蜗结构正常;对照组21例,其中男10例、女11例,CI植入年龄(3.0±1.9)岁,1例为双侧植入,共计22耳,术前影像学检查耳蜗结构及蜗神经形态均正常。除3例(3耳)CND患者植入澳大利亚Cochlear公司CI422电极外,其余患者均植入CI24RECA或CI512电极。所有患者均开机6个月以上,采用Customer Sound EP软件记录耳蜗内电极的蜗神经电刺激复合动作电位(electrically evoked compound action potential,ECAP),并绘制耳蜗不同部位电极的ECAP增益曲线。采用广义线性混合效应模型分析分组及电极位置对ECAP诱发阈值、最大振幅、潜伏期及增益曲线坡度的影响。结果对照组所测电极周围均可记录到ECAP反应,引出率为100%;而CND组ECAP总引出率为71%(859/1210),且由1号电极至22号电极ECAP引出率逐渐降低。与对照组相比,CND组患者ECAP诱发阈值提高、最大振幅降低、增益曲线坡度减小、ECAP潜伏期延长,差异有统计学意义(P值均<0.01)。统计分析显示,电极位置对CND组患者ECAP诱发阈值、最大振幅及增益曲线坡度有显著影响(P值均<0.01),但对ECAP潜伏期无明显影响(P>0.05);而电极位置仅对对照组ECAP阈值有影响(P<0.05)。CND患者由1号电极至22号电极ECAP诱发阈值呈逐渐增高趋势,而最大振幅及增益曲线坡度呈逐渐降低趋势。结论与蜗神经形态正常的感音神经性听力损失患者相比,CND患者不仅残余螺旋神经节细胞数量减少,其对电刺激的反应也存在不同程度的下降。CND患者蜗神经损伤程度个体间差异较大,总体上由耳蜗底转至耳蜗顶转呈逐渐加重趋势。

ObjectivesThis study aimed to evaluate the responsiveness of cochlear nerve to electrical stimulation in patients with cochlear nerve deficiency(CND),to compare their results with those measured in implanted children with normal-sized cochlear nerves,and to investigate the characteristics of the cochlear nerve injury of children with CND.MethodsParticipants were children who underwent cochlear implantation at Shandong Provincial ENT Hospital from January 2012 to January 2020,including CND group and control group.The CND group included 51 subjects(male:20;female:31)who were diagnosed with CND and had normal cochlea.For the CND group,four children had been bilaterally implanted,the mean implantation age was(2.7±1.5)years old.The control group included 21 subjects(male:10;femal:11)who had normal-sized cochlear nerve and normal cochlea.For the control group,all children had been unilaterally implanted except one,and the mean implantation age was(3.0±1.9)years old.Three subjects in the CND group used CI422 electrode arrays,and all the other subjects used CI24RECA/CI512 electrode arrays.The electrically evoked compound action potentials(ECAP)had been tried to record for each electrode using Custom Sound EP software(v.4.3,Cochlear Ltd.)at least six months post first activation.Furthermore,ECAP amplitude growth functions(AGF)were measured at multiple electrode locations across the electrode array.Generalized linear mixed effect models with the subject group and electrode location as the fixed effects and subjects as the random effect were used to compare results of ECAP measurements.ResultsIn the control group,ECAP could been recorded at all electrodes(100%),but it could only be recorded in 71%(859/1210)electrodes in the CND group.Additionally,the percentage of electrodes with measurable ECAP decreased from electrode 1 to electrode 22 in the CND group.Compared to the control group,the ECAP thresholds significantly increased,the ECAP amplitudes and AGF slopes significantly decreased,and the ECAP latency significantly increased in the CND group(P<0.01).GLMM showed that the stimulating site had a significant effect on the ECAP threshold,maximum amplitude,and AGF slope(P<0.01),but had no significant effect on the ECAP latency(P>0.05)in the CND group.However,the stimulating site had no significant effects on the ECAP measurements in the control group.Furthermore,the functional status of cochlear nerve varied greatly among CND group.From electrode 1 to electrode 22,the ECAP thresholds gradually increased,the ECAP maximum amplitudes and AGF slopes gradually decreased in the CND group.ConclusionCompared with patients with normal-sized cochlear nerve,not only the number of residual spinal ganglion neurons reduce,but also the function of spinal ganglion neurons damages in CND patients.The degree of cochlea nerve deterioration varies greatly among CND patients.Generally,the deterioration of cochlear nerve tends to increase from the basal to the apical site of the cochlea.