Effect of Electrode Insertion Angle on Cochlear Implantation Outcomes in Adult and Children Patients with Sensorineural Hearing Loss

Abstract

Purpose. To determine the role played by electrode insertion angle in cochlear implantation (CI) outcomes in adult and children patients with sensorineural hearing loss (SNHL). Methods. Adults ( n = 10 ) and children ( n = 19 ) with SNHL undergoing CI in a tertiary specialized hospital were retrospectively enrolled. The measurements were evaluated before and after CI surgery using sound field audiometry and speech recognition tests. Questionnaires were used to assess subjective benefits. Electrode insertion angles were determined using postoperative X-rays. Results. Both adult and children patients showed significant improvements in hearing, speech performance, and audiology and speech-related quality of life after CI. The angular insertion depths of adult and children group were 323.70 ± 43.57 ° and 341.53 ± 57.07 °, respectively, showing no significant difference. In the adult group, deeper insertion depths were found to be strongly linked to lower postoperative pure tone thresholds at 12 months and higher postoperative disyllabic Word Recognition and Sentence Recognition Scores at 6 months (all P < 0.05 ). In the children group, deeper insertion depth had a positive correlation with postoperative monosyllabic Word Recognition Scores 6 and 12 months after CI surgery (both P < 0.05 ). Multiple linear regression models were constructed to predict disyllabic Word Recognition Scores at 6 and 12 months postoperatively in the children group, in which insertion angle, duration of hearing loss, and preoperative questionnaire result were identified as dependent variables. Conclusions. Greater angular insertion depths resulted in improved hearing and speech performances after CI. The benefits of greater angular insertion depths can be found in both adult and children patients and last for at least 12 months. Clinicians are expected to determine the optimal implantation direction during CI and ensure the insertion depth to improve the speech rehabilitation of patients.

Systematic Review of Intracochlear Measurements and Effect on Postoperative Auditory Outcomes after Cochlear Implant Surgery

“…Of 3,091 electrodes, there were 1,646 perimodiolar and 1,445 straight electrodes. There were 20 cohort studies (6,9,12,14,(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), 10 case series (5,(10)(11)(12)(36)(37)(38)(39)(40)(41), and 2 cross-sectional studies (42,43). A graphical representation of each measurement is depicted in Figure 2, and a summary of the number of studies with the salient correlation is depicted in Figure 3.…”

“…The selection of the correct auditory outcome test is imperative, as exhibited by the mixed picture demonstrated where different speech testing resulted in different relationships (34,39). Minimum follow-up durations ranged from 4 to 12 months, and one study noted significant missing data for follow-up at 6 months (37). Confounding was a common issue, with all studies at moderate to severe risk.…”

“…Although many papers used regression to address confounding (5,6,10,25,27,41), this can only be overcome with randomized controlled trials. Selection bias arose from selecting "smooth" operations (37), or from insufficient selection criteria reporting (10,22,24,31,36,40). As this search was limited to English, future searches could include other languages to deliver a global perspective.…”

“…Twenty-two studies with 23 populations (n = 1921) reported on AngI (Table 2). Eleven studies (n = 633) identified a positive correlation with AngI (12,14,21,24,28,29,36,37,39,41,42). Two studies (n = 277) examined both straight and precurved electrodes (14,42).…”

“…Oxford CEBM level of evidence ranged between levels 2 and 4 (44). There were 6 prospective cohort studies (level 2) (9,20,23,25,30,34), 15 retrospective cohort or cross-sectional studies (level 3) (6,12,14,22,24,(26)(27)(28)(29)(31)(32)(33)35,42,43), including two mixed retrospective and prospective studies (12,42), and 10 retrospective case series (level 4) (5,10,11,21,(36)(37)(38)(39)(40)(41). No randomized controlled trials or systematic reviews were identified.…”