Dhanasingh Anandhan
MED-EL GmbH, Fürstenweg 77a, 6020, Innsbruck, Austria.
World J Otorhinolaryngol Head Neck Surg. 2018 Dec 29;5(2):117-121. doi: 10.1016/j.wjorl.2018.09.004. eCollection 2019 Jun.
Cochlear duct length (CDL) measurement or estimation is a hot topic for various research groups in the cochlear implant (CI) field as of today. Getting the CDL along the outer wall (LW) and organ of corti (OC) is possible but considering the clinical application especially in the selection of the electrode array length and applying Greenwood's frequency function, we need to have a clear understanding on the CDL in general and as well on the Greenwood's frequency function. It is very clear from the histology images of the cochlea with straight electrode inside, that the electrode locates itself right under the basilar membrane. Also the Greenwood's frequency function involves a variable that corresponds to the CDL at the basilar membrane/organ of corti level. This brings us to conclude that the CDL at the OC is relevant for the selection of electrode array length and in applying Greenwood's frequency function. The ratio between CDL (LW) and CDL (OC) is 0.9 which is a very important number that needs to be remembered when converting CDL (LW) to CDL (OC).
截至目前，耳蜗管长度（CDL）的测量或估计是人工耳蜗（CI）领域各研究团队的热门话题。沿外壁（LW）和柯蒂氏器（OC）获取CDL是可行的，但考虑到临床应用，特别是在电极阵列长度的选择以及应用格林伍德频率函数时，我们需要对CDL总体情况以及格林伍德频率函数有清晰的认识。从内部有直电极的耳蜗组织学图像可以非常清楚地看到，电极位于基底膜正下方。而且格林伍德频率函数涉及一个与基底膜/柯蒂氏器水平的CDL相对应的变量。这使我们得出结论，OC处的CDL与电极阵列长度的选择以及应用格林伍德频率函数相关。CDL（LW）与CDL（OC）的比值为0.9，这是在将CDL（LW）转换为CDL（OC）时需要记住的一个非常重要的数字。
