| Cochlear implants can help to provide a sense of sound for severe to profoundsensorineural deafness. With the increasing sponsorship of the national cochlearimplantation project and charity funds, as well as the support ofthe New rural Cooperative Medical care System, the number of cochlear implantationsurgery increased significantly in the past two years. At the same time, due to theprogress of the surgical technique, surgical indications are further widened. Patientswho suffer from inner ear malformations and severe deafness with residual hearingare now in accordance with the operation indications. However, lymphatic orcerebrospinal fluid gusher is frequently encountered in the implantation surgery of amalformed cochlea."Gusher" refers to lymph or cerebrospinal fluid gush out of thecochlear duct continuously after tympanic canal fenestration. Which mainly occur inthe malformed cochlea. The occurrence of CSF gusher could make it difficult to insertelectrodes, which may also cause damage of the inner ear structure in the process ofthe insertion. In addition, improper handling of gusher can lead to postoperativecomplications such as cerebrospinal fluid leak and intracranial infection. Inner earmalformations including cochlear deformity, vestibule malformation，semicircular canal malformation, internal auditory canal and vestibular aqueduct malformation(e.g.,Large vestibular aqueduct syndrome, LVAS). And cochlear deformity is furtherdivided into Michel deformity, Cochlear aplasia, Common cavity, Cochlearhypoplasia, Incomplete partition type I(IP-I) and Incomplete partition type II(IP-II orMondini deformity). In recent years, some authors reported different results ofpatients with inner ear malformations after cochlear implantion, and the "blowout"mainly occurs in the patients existing abnormal traffic between cochlea or vestibularwith intracranial subarachnoid. However, there are few reports about thepostoperative effect for patients with gusher occurred during the cochlearimplantation operation.Objective1. To observe the effect of the CSF gusher on the operation and the results ofelectrode implantation.2. To compare the boot debugging and postoperative hearing threshold betweenthe group "blowout" and the "non-blowout" group.3. To explore the hearing change after the implantation of electrode of thepatients who have residual hearing before the operation.Method1. Data and grouping:349patients who had cochlear implantation surgeries in theFirst Affiliated Hospital of Zhengzhou University from March,2010to February,2014, of which78cases with inner ear malformations, including41cases of LVAS,21cases of IP-II/EVA,13cases of vestibular and semicircular canal malformation,3cases of internal auditory canal stenosis.Grouping: There were22patients (14males and8females, age from11monthsto24years old, with average age of4.7years old) with lymph/cerebrospinal fluidflow out of the cochlear duct continually or flow in abundance after tympanic canalfenestration, which were selected as group A (8cases were serious,14cases weremild), including7cases of LVAS,15cases of IP-II/EVA. Among them,17cases hadresidual hearing. Another22patients(13males and9females, age from1years old to21years old, with an average age of5.1years old)who were not suffered from CSF gusher were selected as control group, including16cases of LVAS,6cases of IP-II/EVA.19cases have residual hearing in this group.2. Audition and imaging examination: Subjective hearing tests including pure toneaudiometry or infantile behavior listening. Objective hearing tests including multipleauditory steady state evoked responses(ASSR), auditory brainstem response(ABR),Distortion product otoacoustic emissions(DPOAE), acoustic immittance and stapesmuscle sound reflection. Imaging: temporal bone CT, head MRI and the inner earfluid of MRI were conventional before the operative. Postoperative X-ray of thecochlear was also necessary to verify the position of electrode.3. Operation methods and the management of CSF gusher: Entering into tympaniccavity through facial nerve fossae, making the round window niche and circulardiaphragm clear to see, implanting electrodes through the round window. If CSFgusher occurred in the operation, the electrodes implantation was suspended andwaited for the decreases of lymph/cerebrospinal fluid pressure or using mannitol tolower intracranial pressure, and then inserted the electrodes. Slow and gentleoperation was applied to avoid damaging the structure of the inner ear, and the innerear were tightly sealed by fascia.4. Boot debugging and postoperative hearing threshold evaluation: boot it onemonth after the operation, test electrode impedance values, the electrode reactionthreshold (electrical threshold, T value) and maximum comfort threshold (comfortablelevels, C value); The postoperative follow-up duration of36cases (18cases ofblowout group and20cases of control group) were more than half a year’s, and testthe sound field hearing threshold six months after the operation.5. Residual hearing: If the patient had residual hearing and could cooperate withpure tone test before the operation, the residual hearing were tested before and afterthe surgery (before booting) on the same test conditions.4cases of blowout group and5cases of control group were compared with5cases with normal cochlear structuresat the same time. The cases which were not lost all the residual hearing wereconsidered as hearing retained.Result1、The operation and the results of electrode implantation: Mild "blowout" during the operation did not affect the implantation of theelectrodes, but serious "blowout", because of the huge force introduced by thelymph/cerebrospinal fluid when it flowed outward, increased the difficulty of theimplantation. Of the22cases who suffered from CSF gusher in this study,20caseswere completely implanted,2severe blowout cases were IP-II/EVA. When theywere implanted with MEDEL SONATA super soft long straight electrode, twocochlear electrodes were not implanted. The patients of control group were allcompletely implanted. Postoperative X-ray of cochlear showed that all the electrodeswere in a proper location. There was no case with postoperative cerebrospinal fluidleakage and meningitis.2、 The result of boot debuggingAll cases got hearing sense after activation of the device one month after theoperation.The average of the electrode impedance values, T value and C value of theblowout group were respectively12.26±2.38k,112.37±21.62CL and130.36±21.54CL; of the control group were respectively11.12±2.93k，125.15±17.84CL and136.88±24.72CL. The differences between the two groups werenot statistically significant(P＞0.05).3、 Postoperative auditory threshold：Test the sound field hearing threshold six months after the operation if thepostoperative duration of follow-up is more than half a year’s. The test frequency was250,500,1000,2000and4000Hz. The average auditory threshold of blowout group(18cases) was38.42±10.47dBHL and the control group (20cases) was40.36±6.59dBHL. The differences between the two groups were not statisticallysignificant (P＞0.05).4、The retention of residual hearingIn the blowout group, there were4patients with residual hearing before theoperation,2cases were retained after the operation. In the control group, there were5patients with residual hearing before the operation,3cases were retained after theoperation. In the normal cochlear structures group, there were5patients with residualhearing before the operation,4cases were retained after the operation. Conclusion：1、The occurrence of severe CSF gusher increases the difficulty of electrodeimplanting, especially for the super soft long straight electrode. So carefulpreoperative assess and preparation are necessary.2、Proper solutions for CSF gusher had no significant negative effect on theelectrode impedance values, T value, C value and postoperative auditory threshold.3、Electrodes implantion had certain degree of negative influence on the residual. |
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