Kruschinski Carsten, Weber Benno Paul, Pabst Reinhard
Department of Functional and Applied Anatomy, Medical School of Hannover, Germany.
Otol Neurotol. 2003 Sep;24(5):823-7. doi: 10.1097/00129492-200309000-00022.
To elucidate possible mechanisms of facial nerve costimulation after cochlear implantation that are supposed to result from the close cochlea to facial nerve contact.
One of the postoperative complications of cochlear implantation is facial muscle twitching, which has preferentially been found in otosclerotic patients. It impairs hearing benefits because of deactivation of electrodes and can still not be adequately prevented.
A total of 13 temporal bones were dissected to quantify where the labyrinthine portion of the facial nerve is closest to the scala tympani, the placement site of the cochlear implantation electrode array. After the typical operative procedures to find out the number of electrodes lying closest to the facial nerve were performed, a cochlear implantation array was inserted into four specimens. The clinical records of 14 otosclerotic patients were investigated to correlate these results with the position of in vivo deactivated electrodes.
The closest distance between the scala tympani and the nerve was only 0.33 mm (+/-0.14). On average, after insertion of 23 electrode resp. marking rings, the facial nerve was reached. This is clinically the position of most frequently deactivated electrodes to prevent postoperative facial nerve costimulation.
These investigations support the hypothesis that a direct current spread at the site of the facial nerve crossing the cochlear basal turn is most likely the reason for postoperative facial muscle twitching facilitated in otospongiotic bone. Prevention could therefore be achieved by cochlear implantation designs and surgical techniques that take into consideration the site of closest contact.
阐明人工耳蜗植入后面神经共刺激可能的机制，这种机制被认为是由于耳蜗与面神经紧密接触所致。
人工耳蜗植入术后并发症之一是面部肌肉抽搐，在耳硬化症患者中尤为常见。由于电极失活，它会损害听力益处，且仍无法得到充分预防。
解剖13块颞骨，以量化面神经迷路部分最靠近蜗鼓阶（人工耳蜗植入电极阵列的放置部位）的位置。在完成找出最靠近面神经的电极数量的典型手术操作后，将人工耳蜗植入阵列插入四个标本中。调查14例耳硬化症患者的临床记录，以将这些结果与体内失活电极的位置相关联。
蜗鼓阶与神经之间的最短距离仅为0.33毫米（±0.14）。平均而言，在插入23个电极或标记环后触及面神经。这在临床上是最常失活电极的位置，以防止术后面神经共刺激。
这些研究支持以下假设，即面神经穿过耳蜗基底转部位的直流电扩散很可能是耳海绵化骨中术后面部肌肉抽搐加剧的原因。因此，可以通过考虑最紧密接触部位的人工耳蜗植入设计和手术技术来实现预防。
