掩蔽刺激间期对神经反应遥测波形的影响

目的最直接测试人工耳蜗使用者听神经活性的是电诱发听神经复合动作电位(electrically evoked com-pound action potential, ECAP)。用于记录Nucleus CI24M使用者ECAP的遥测系统称为神经反应遥测(neural re-sponse telemetry, NRT)系统。本次试验的目的是通过测试不同掩蔽刺激间期(masker advance)条件下的ECAP反应波形得出ECAP反应波形幅值的变化规律。方法25位Nucleus CI24M多导人工耳蜗使用者参加了本次试验。分别测试每位患者第3、5、10、15、20号5个电极的ECAP波形。选取每位患者反应波形最清晰的电极作为该患者的试验电极。分别在不同掩蔽刺激间期条件下记录患者的反应波形并进行分析。结果不同患者之间及同一患者不同掩蔽刺激间期之间反应波形幅值均存在差异。不同患者的听神经从不应期中恢复的速度不同。掩蔽刺激间期小于0.5ms时患者的反应幅值最大。当掩蔽刺激间期为4ms以上时有超过半数的患者记录不到反应波形。结论掩蔽刺激间期可显著地影响ECAP反应波形的幅值。记录ECAP反应波形的最佳掩蔽刺激间期为小于0.5ms。

THE EFFECTS OF CHANGING THE MASKER ADVANCE ON THE NRT RESPONSES

Objective The most direct measurement of auditory nerve activity in cochlear implant users is the electrically evoked compound action potential(ECAP). The telemetry system used to measure the ECAP in Nucleus CI24M users is referred to as neural response telemetry(NRT).The aim of this study is to summarize the effects of changing the masker advance on ECAP response amplitudes by recording ECAP responses with different masker advances. Methods 25 patients who received Nucleus CI24M participated in this study. ECAP responses of the No. 3, 5, 10, 15, 20 electrodes of each patient were recorded. The elec-trode with best waveform was selected to be the tested elctrode in this study for each patient. ECAP re-sponses were recorded using different masker advances. Results There were variations in the amplitude of the response waveform and the recovery of auditory nerve across subjects. Even in one subject there was variation when different masker advances were used. The largest response amplitudes were recorded for the masker advances under 0.5ms. When the masker advance was above 4ms, no responses was present in the waveforms in more than half subjects. Conclusions Masker advance makes great influence on the amplitudes of ECAP responses. The optimizing masker advances to record ECAP response are under 0.5ms.