Department of Otorhinolaryngology and Head & Neck Surgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands.
Hear Res. 2011 Feb;272(1-2):95-107. doi: 10.1016/j.heares.2010.10.012. Epub 2010 Oct 31.
Criteria for cochlear implantation keep expanding and people with substantial residual low-frequency hearing are considered candidates for implantation nowadays. Therefore, electro-acoustical stimulation in the same ear (EAS) is receiving increasing interest. We have investigated the effects of intracochlear electrical stimulation on acoustically evoked auditory-nerve activity, using a forward masking paradigm. The stimulation electrode was placed in the basal turn of the cochlea. Compound action potential (CAP) recordings were performed in guinea pigs with severe high-frequency hearing loss and in normal-hearing control animals. In normal-hearing animals, electrical stimulation generally suppressed CAPs, especially at high acoustic frequencies (8 and 16 kHz) and low sound levels. At low frequencies (0.5 and 1 kHz), suppression was observed only at high sound levels. In animals with a high-frequency hearing loss, suppression of CAPs at low frequencies was substantially less compared to control animals, even at high current levels and temporal overlap of acoustic and electric stimuli. Hence, effects of electrical stimulation substantially differed between normal-hearing animals and animals with a high-frequency hearing loss. These findings stress the need for a proper animal model when investigating EAS. We conclude that in case of high-frequency loss, the basal part of the cochlea can be stimulated electrically with little effect on responses to low-frequency acoustic stimuli.
适应证不断扩大，目前有大量低频残余听力的患者被认为是植入的候选者。因此，同侧电-声刺激（EAS）越来越受到关注。我们采用前掩蔽范式研究了耳蜗内电刺激对声诱发听神经活动的影响。刺激电极置于耳蜗基底回。在高频听力损失严重的豚鼠和正常听力对照动物中进行复合动作电位（CAP）记录。在正常听力动物中，电刺激通常会抑制 CAP，特别是在高声学频率（8 和 16 kHz）和低声级时。在低频（0.5 和 1 kHz）时，仅在高声级时观察到抑制。在高频听力损失的动物中，与对照动物相比，CAP 的抑制程度在低频时要小得多，即使在高电流水平和声音与电刺激的时间重叠时也是如此。因此，电刺激对正常听力动物和高频听力损失动物的影响有很大的不同。这些发现强调了在研究 EAS 时需要适当的动物模型。我们得出结论，在高频损失的情况下，耳蜗的基底部分可以用电刺激，而对低频声刺激的反应影响很小。
