[An analysis of surgical management of difficulties during cochlear implant with inner ear anomalies]

Objective:The purpose of this study is to review the difficulties that can occur during cochlear implant surgery in patients with inner ear abnormalities and the management. Method:A retrospective analysis was made on 186 cases of cochlear implant with inner ear malformation, the types of inner ear malformations included 6 cases（3.23%） of isolated semicircular dysplasia, 137 cases（73.66%） of isolated large vestibular aqueducts, 26 cases（13.98%） of Mondini malformations, 6 cases（3.23%） of incomplete septal type Ⅲ, 3 cases（1.61%） of internal auditory stenosis, 7 cases（3.76%） of cochlear dysplasia and 1 case（0.54%） of incomplete septal typeⅠ. Two hundred patients with normal inner ear structures were randomly selected as the control group. The data collected included the types of inner ear abnormalities, intraoperative manifestations, clinical management strategies, and postoperative speech rehabilitation, and the literature was reviewed. Result:148 patients（77.49%） with inner ear malformation underwent successful surgery, electrode insertion was incomplete in 6 patients（3.14%）, and cerebrospinal fluid blowout occurred in 29 patients（15.18%）, it was difficult to locate the window because of the abnormal structure of the window in 8 cases（4.19%）. In 191 patients, the facial recess approach was adopted intraoperatively, and 17.8% of the patients had significant structural abnormalities of the facial nerve, significantly more than the group with normal inner ear structure. Only 1 patient showed delayed facial nerve paralysis 1 week after surgery, and recovered well after treatment. 6.81% of the patients adopted the expanded round window approach, which was significantly lower than that of the group with normal inner ear structure（28%）. There was no significant difference between patients with inner ear malformation and patients with extremely severe deafness with normal inner ear structure who received cochlear implant in speech rehabilitation. Conclusion:Cochlear implant is safe, feasible and effective for patients with inner ear malformation. For patients with inner ear malformation, special attention should be paid to the preoperative imaging reading to predict the possible risks during the operation. The safest surgical plan, including the type of electrode and the manner in which the window is opened, must be prepared before the operation, and the operation must be performed or directed by an experienced surgeon who can adjust the optimal surgical plan according to what is seen during the operation.