人工耳蜗植入前电刺激听神经复合动作电位检测方法的建立和初步应用

目的 建立术中利用探测电极施行电刺激听神经复合动作电位(electrically evoked auditory nerve compound active potentials,ECAP)检测的方法,在植入人工耳蜗装置前评估患者耳蜗听神经功能状况.方法 选择20例人工耳蜗植入患者,其中耳蜗形态发育正常12例,5例双侧前庭导水管扩大,3例双侧耳蜗Mondini畸形.测试完成后全部使用Cochlear人工耳蜗.全麻后常规人工耳蜗手术进路,行标准耳蜗鼓阶开窗,将自制测试用多通道试验电极置入鼓阶,电极连接Cochlear公司体外言语处理器及自制电刺激发生器,连接电脑,采用Custom Sound EP 2.0软件,调整优化刺激参数进行神经反应遥测(neural responsetelemetry,NRT)初步了解听神经功能状态;刺激强度以5 CL为步长递减或递增至反应阈值给予电刺激脉冲,同时自动记录ECAP波形和阈值.植入人工耳蜗后常规进行NRT检测,记录ECAP波形和阈值;术后1个月患者开机后采集T、C值,将两种电极测试所得阈值和开机C值进行相关性研究,并进行数据统计分析.结果 试验电极ECAP引出率为90%,商业电极ECAP引出率为90%,平均阈值分别为(160.50±15.12)CL和(160.00±11.27)CL,两者经统计学检验没有显著性差异(P>0.05);和开机后C值(177.40±10.61)有明显相关性(R2=0.844,r=0.919).结论 成功建立了术中植入人工耳蜗装置前的ECAP检测方法,为内耳和/或听觉通路发育异常及无残余听力患者提供有效的听神经反应信息,对了解听觉系统发育程度及初步预测术后患者康复情况提供客观依据.

The Establishment and Application of Electrically Evoked Auditory Nerve Compound Action Potential Test Method before Cochlear Implantation

objective To establish an electrically evoked auditory nerve compound action potential （ECAP） test procedure in order to assess the auditory nerve functions before cochlear implantation. Methods Twenty cochlear implant patients were selected, including 12 subjects with normal cochlear structure, 5 subjects with bilateral enlarged vestibular aqueducts, 3 with bilateral Mondini cochlear malformation. After the success of anesthesia, all the patients＇ tympani bands were generally opened and the multi-channel test electrodes were placed into the tympani bands. The electrodes were connected to the Cochlear speech processor and electrical stimulation generator via the computer. By the Custom Sound EP 2.0 software, the stimulation parameters were adjusted and optimized to perform neural response telemetry （NRT） test. The stimulation intensity decreased or increased by 5 CL gradually until to the threshold. The ECAP waveforms and thresholds were automatically recorded when giving electrical stimulation pulses. After cochlear implantation, the NRT was regularly performed to record ECAP waveforms and thresholds. One month later, the T and C values of mapping were tested after switchon. The correlation between the ECAP thresholds of the two electrodes and the C values of switch-on were statistically analyzed. Results The presences of ECAP by test electrodes and commercial electrodes were both 90% and the average thresholds were （160.50 ± 15.12） CL and （160.00±11.27） CL respectively, showing no significant difference （P〉0.05）. The thresholds were related to the C values after witch-on （177.40±10.61） （R2=0.844,r=0.919）. Conclusion Through this study, an ECAP test method before cochlear implantation has been successfully developed. The ECAP can provide reliable and effective information about the auditory nerve responses in patients with inner ear and /or auditory pathway abnormalities and no residual hearing. This is useful in evaluating the development of auditory system and predicting the postoperative rehabilitation outcome of the patients.