Bilateral Cochlear Implantation: Achieving a Stereo Effect

2010年3月3日

Sancak Yuksel, MD
Associate Professor

As we all know, normal hearing is binaural. Binaural hearing provides some major benefits: better and targeted hearing in a noisy environment, better localization of sounds, and more natural and balanced hearing quality. If this is the case, would bilateral implantation prove more beneficial than unilateral implantation?

经过三十年和成千上万的人工耳蜗（CI），我们知道CIS有效，并为听力损失的患者提供更好的听力。但是，即使单方面的耳蜗植入物极大地有助于理解安静的环境中的言语，但在嘈杂的环境中，它们的效率也会下降。单方面植入的声音定位也相对较差。如上所述，这是正常个体和助听器接受者双耳刺激的两个重要功能。因此，对双边人工耳蜗的兴趣越来越大。

Three mechanisms in binaural hearing have been demonstrated to achieve improved acoustic results:

  • In the head shadow effect, which has the largest impact on binaural hearing in a noisy environment, the head blocks some of the background noise. So, the protected ear achieves a better signal-to-noise ratio.
  • In the binaural squelch effect, the central hearing center receives and integrates different signals from both ears, which results in augmented hearing.
  • When both ears receive similar signals, this is perceived as louder. This phenomenon is called the binaural summation effect.

Studies have shown that children with bilateral CIs are able to discriminate between the locations of two sound sources better with both, rather than with either one, of their implants. Laszig et al. demonstrated that accuracy of localization was 90° in a unilateral implant. This was reduced to 50° in a bilateral implant. Other studies demonstrated that, in children and adults, speech intelligibility is better under noisy conditions. Peters et al., in a recent study, found significant increase in speech discrimination scores in children with bilateral implants in comparison with their best performing unilateral implants.

There are other benefits of bilateral CIs. Implanting both ears ensures that the ear with better potential receives stimulation, as they might have different levels of neural survival. If there is a technical problem with one of the implants, at least one functional implant provides hearing until the problem is resolved. There are also subjective and qualitative benefits of bilateral implants. Adults feel less stressed in social environments. Additionally, children report that they love having “both ears” like other children, and function better at school.

除了优势外，还有反对双边独联体的论点，这些论点通常集中在另一只耳朵的财务成本和风险上。在植入物失败的情况下，可以重新植入，但我们需要承认，有可能通过植入来损害耳蜗的风险，这可能排除未来的非遗传听证会。另一方面，当从单侧或双边的顺式受益时，儿童大脑的可塑性期非常关键。言语和语言发展发生在此期间；因此，有人认为，植入越早，好处越好。其他问题是外科/麻醉风险增加以及对前庭系统的影响。应该注意的是，第二种植入物的风险等于第一植入物的风险，但是额外的好处不如第一个植入物。尽管同时植入似乎更具成本效益和有益，但在同时或顺序（第二手术）的同时或顺序（在第二手术中）的手术耐受性均相等。据估计，双侧人工耳蜗手术的前庭脱落风险约为10％。在儿童中，这甚至更小。 Currently, there is hesitancy in insurance companies to approve patients for second side implant because of the increased cost. However, when improved quality of life measures in patients with bilateral implants were incorporated, this cost seems decreased.

In conclusion, hearing with both ears is better than hearing with one. Bilateral cochlear implantation is a safe and appropriate procedure that provides improved sound localization and enhanced speech perception in noise. Although there are some concerns about it, it appears that it will be the standard of practice in the future for children with profound hearing loss.

参考

  1. Papsin BC, Gordon KA. Bilateral cochlear implants should be the standard for children with bilateral sensorineural deafness. Curr Opin Otolaryngol Head Neck Surg 2007; 16(1):69-74.
  2. Ramsden JD, Papsin BC, Leung R, James A, Gordon KA.儿童的双边同时人工耳蜗植入：我们的前50例。Laryngoscope 2009; 119:2444–2448.
  3. Basura GJ, Eapen R, Buchman CA.Bilateral cochlear implantation: Current concepts, indications, and results.Laryngoscope 2009; 119:2395–2401.
  4. Brown KD, Balkany TJ.双边人工耳蜗的好处：审查。Curr Opin Otolaryngol Head Neck Surg 2007; 15:315–318.
  5. Laszig R，Aschendorff A，Stecker M等。双边电刺激的好处the nucleus cochlear implant in adults: 6-month postoperative results.Otol Neurotol 2004; 25:958–968.
  6. Peters BR, Litovsky R, Parkinson A, et al.Importance of age and postimplantation experience on speech perception measures in children with sequential bilateral cochlear implants.耳醇Neurotol 2007;28（5）：649-657。
  7. Hearing Loss Web. Bilateral Cochlear Implants. (Accessed January 24, 2010.)
  8. 人工耳蜗美洲。美国双边人工耳蜗植入。（2010年1月24日访问。）
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