不同刺激模式下人工耳蜗使用者EABR的研究

EABR in cochlear implant users by different stimulation modes

目的研究不同刺激模式对人工耳蜗植入术后电诱发听觉脑干反应(EABR)波形和阈值的影响。方法对9名Nucleus 24M人工耳蜗植入患者术后分别测试电极E3,E10,E20(分别代表蜗底、蜗中、蜗顶)在不同刺激模式(MP1+2、MP1、MP2、BP+1、CG)下的EABR阈值,比较分析强度为200～255电流级(currentlev-el,CL;约阈上30电流级)刺激时各电极在五种刺激模式下引出的EABRⅢ波和Ⅴ波引出率、潜伏期及其幅值。结果(1)Ⅲ波总检出率为44.44%,电极3,10,20的Ⅲ波检出率分别为22.22%,42.22%,68.89%,蜗顶较高(!2=58.2,df=4,P﹤0.01)。单极模式下的Ⅲ波检出率较高(!2=28.5,df=4,P﹤0.01)。(2)MP2刺激模式下Ⅲ波平均潜伏期为2.06ms,电极3,10,20间无统计学差异(P=0.299﹥0.05)。(3)MP1+2,MP1,MP2,BP+1,CG模式下EABRⅤ波检出率分别为96.3%,94.4%,96.3%,14.8%,33.3%,单极模式下(MP1+2,MP1,MP2)的Ⅴ波检出率较高(!2=75.667,df=4,P<0.005)。三个电极位点间无明显差别(!2=2.600,df=2,P=0.273>0.05)。(4)在蜗顶诱发EABR的电刺激阈值较低,E20和E3(P=0.001<0.01)、E20和E10(P=0.002<0.01)均存在统计学差异。单极、双极、共地模式的阈值依次升高,而单极模式MP1、MP2、MP1+2之间无统计学差异。(5)电极3,10,20的Ⅴ波潜伏期分别为4.09±0.16ms,4.02±0.19ms,3.70±1.21ms,蜗顶的Ⅴ波潜伏期短于蜗中段和蜗底(P=0.001<0.01,P=0.001<0.01)。刺激模式间的差别无统计学意义(P=0.309>0.05)。(6)EABRⅤ波振幅在电极位点间(P=0.06>0.05)及刺激模式间(P=0.093>0.05)均无统计学差异。但个体差异大,可认为蜗顶和单极刺激模式倾向于获得较大的振幅。(7)本实验同时采用了同侧和对侧记录,发现同侧记录的波形和对侧记录的波形相似,部分反而更清晰,波形分化更好,随刺激强度的下降Ⅴ波消失稍晚。结论人工耳蜗植入术患者术后单极刺激下易检测出EABR波形,检出率高,波形分化较好,波幅大,而采用双极及共地模式EABR阈值较高或难以引出波形。为此,建议在对人工耳蜗植入患者术后进行EABR测试时可首选单极刺激模式,从易诱发出振幅较大的波形的蜗顶电极开始,并且有可能的话进行同侧与对侧同时记录。

Objective To investigate the impact of stimulation modes on electrically evoked auditory brainstem response （EABR）. Methods Three electrodes in 9 Nucleus 24M cochlear implant users, along the electrode array from the base towards the apex, were stimulated for EABR registration. EABRs were recorded in MP1＋2, MP1, MP2, BP＋1, CG stimulation modes respectively. The detection rates, peak latencies and amplituds of EABR wave Ⅲ and Ⅴ were compared between the 3 electrodes, as well as the different stimulation modes. Results （1） The a average detection rates of the wave Ⅲ was 44.44%, and it was 22.22%, 42.22% and 68.89% in E3, E10 and E20, respectively, indicating a higher rate in the apex （ X^2= 58.2, df= 4, P 〈 0.01） and in the monopolar mode （X^-2= 28.5, df= 4, P〈 0.01）. （2） The average latency of wave Ⅲ was 2.06 ms with no statistical difference between the 3 electrodes （P=0.299〉0.05）. （3） The EABR wave Ⅴ detection rate was 96.3%, 94.4%, 96.3%, 14.8% and 33.3% in MP1＋2, MP1, MP2, BP＋1 and CG mode, resoectively. The detection rate in the MP mode was higher than others （ X^2 = 75.667. df = 4, P 〈 0.005 ）. There was no statistical difference in the detection rate among the three electrodes （X^2 = 2.600, df= 2, P = 0.273 〉 0.05）. （4） EABR threshold was lower in the apex, with difference between E20 and E3 （P = 0.001 〈 0.01 ）, as well as between E20 and E10 （P = 0.002 〈 0.01）. The threstholds rose in the order of the MP, BP and CG mode. No difference existed between MP1, MP2 and MP1 ＋2. （5） The wave Ⅴ latency of E3, E10 and E20 was 4.09±0.16 ms, 4.02 ± 0.19 ms and 3.70 ± 1.21 ms, respectively, with the shortest latency in the apex （P = 0.001 〈 0.01, P = 0.001 〈 0.01 ）. There was no statistical difference among the stimulation modes（P= 0.309〉0.05）. （6） Wave V amplitude varied little among the electrodes （P = 0.06 〉 0.05） and the stimulation modes （P=0.093 〉 0.05）. （7） Ipsilateral and contralateral recording were conducted simultaneously. Sometimes ipsilaterally recorded waveforms had a better discrimination than contralateral counterparts. Conclusion Monopolar stimulation mode exhibited advantage than bipolar and common ground mode in some respects. We recommend it as the first choice in EABR registration. What＇s more, ipsilateral and contralateral simultaneous recording is also recommended for a better identification of EABR waveforms.