Nucleus直电极人工耳蜗植入对不同频率残余听力的影响

目的:评估Nucleus直电极人工耳蜗植入对各频率残余听力的影响,探讨耳蜗直电极植入的听力学安全性及其创伤特点。方法:分析23例手术前后能够良好配合纯音听力检查、中耳内耳无明显异常、尚未接受人工耳蜗电刺激的单侧Nucleus直电极人工耳蜗植入者的残余听力变化情况。结果:术前植入侧残余听力在术后有所保留者占60%。将最大输出无反应时的听阈值计为最大输出加上5dBHL,经非参数检验:植入侧1kHz以下各频率的残余听力较术前平均损失约6dBHL,差别有极显著性的意义(P值均<0.01);植入侧2kHz以上各频率及非植入侧各频率较术前平均损失<1dBHL,差别无显著性的意义(P值均>0.05)。结论:Nucleus直电极人工耳蜗植入术后,植入耳多数仍可保留部分残余听力,但其损失在1kHz以下频率重于2kHz以上频率。

The sole effect of the cochlear implantation with Nucleus straight electrodes on residual hearing in different frequencies

AIM:Cochlear implant has been recognized as a very important tool in treating severely sensorial hearing impaired patients. It has been reported that some recipients had conserved part of their residual hearing although the other ones had lost all of theirs after cochlear implantation and a period of electrical stimulation of the cochlear. It has not been reported that the sole effect of cochlear implantation on residual hearing, especially in different frequencies. The goal of this work was to explore the influence of cochlear implantation on residual hearing in each frequency, and to provide an audiological criterion for the safety of cochlear implantation through the Nucleus straight electrodes.METHODS:Pre implant (within 2 weeks) and post implant(ranged: 23-45 days, means 31 days) audiometric evaluation had been done prior to switching on for 23 well cooperating Nucleus 24 M/24K recipients with normal inner and middle ears. There were 13 males and 10 females,4 post and 19 pre linguistic deaf included in this study.Their ages ranged from 4 to 41 years with an average age of 13 years.No response at the maximum output level was assigned as 5 dB HL more than this level in that frequency.Nonparametric statistics was chosen in the analyses of the change of residual hearing in different frequencies and based on contrasting post implant with pre implant residual hearing or contrasting implanted with the non implanted ear of the same recipient.RESULTS:8 of 20(40%) recipients had lost all measurable hearing but the other 12 (60%) recipients had conserved some measurable hearing after implantation. The implanted ears had an average 6-7 dB HL threshold drop and a highly statistic significance difference between pre and post implantation (P< 0.01) weather in 250 Hz, 500 Hz or 1 kHz,but had less than 1 dB HL threshold drop and no statistic significance between pre and post implantation(P >0.05) in weather 2,4 or 8 kHz as in every frequency of the control ears.CONCLUSION: Most of the implanted ears can conserve some degrees of hearing after cochlear implantation with Nucleus straight electrodes. The residual hearing of implanted ears in frequencies under 1kHz are more severely impaired than those above 2 kHz after cochlear implantation. This phenomenon is interesting and the further research should be done in the future.