Characterization of retentive capacity of the subpericranial pocket in cochlear implants with and without a pedestal.

OBJECTIVES/HYPOTHESIS: To quantify the retentive capacity (RC) of the subpericranial pocket (SpP) in children undergoing cochlear implantation (CI) and measure improvements in RC with the addition of a pedestal to the device base. Retention of a CI in an SpP relies on the integrity of surrounding tissues to determine device position and resist movement from external forces. We hypothesize that device position can be controlled and resistance to movement can be improved with placement of a small pedestal on the base of the CI receiver stimulator. STUDY DESIGN: Analysis of prospectively assembled data. METHODS: Ninety-seven patients (145 devices) underwent CI (48 bilateral, 49 unilateral). Intraoperatively, a force gauge measured the displacement force on a template Nucleus 5 (Cochlear Corporation, Sydney, Australia) implant placed in an SpP prior to routine suture fixation of a standard device. In 47 patients (64 devices), displacement forces were also measured for a custom template Nucleus 5 implant with pedestal. RESULTS: Average RC of the SpP for the standard device was 5.59 N ± 2.73 standard deviation (SD), which increased to 9.401 N ± 4.6267 SD with a pedestaled device. Resistance to displacement decreased significantly across trials in both groups (P <.0001). Retentive capacity of the SpP increased significantly with the addition of a pedestaled device (P < .0001). The interaction between device and trial was also found to be significant (P = .05). CONCLUSIONS: The RC of the SpP in children and the ability to resist device migration in the absence of fixation may improve with the addition of a pedestal attached to the device. LEVEL OF EVIDENCE: 2b. Laryngoscope, 126:1175-1179, 2016.

Exploring the relationship between head anatomy and cochlear implant stability in children.

In our experience, surgical outcomes in children have been excellent with a low complication rate. Our aim in this study was to better understand what aspects of our current surgical technique have been successful with a view to retain those that are beneficial as we proceed with implantation of future devices. Because the receiver-stimulator and overlying skin flap may be more vulnerable to damage in children than adults, we concentrated on issues related to the positioning and security of this part of the implant on the head. Three specific areas of vulnerability were explored in separate experiments. In Experiment 1, we determined the effect of the position of the device on the ability of a child to roll their head without allowing contact between the device and a supporting surface. The 'freeroll' angle was determined for devices position conventionally (back position) and for those in which the device is placed in a more anterior position (up position). In Experiment 2, we studied the retentive capacity of the child's pericranium and measured the displacement force required to dislodge an implant from the bed if retained by the calvarium only. In Experiment 3, we compared the skull curvature of children in whom the device was placed in the back versus the up position. These results inform us as how to best proceed with implantation in children using future devices that have thinner and wider receiver-stimulators.

Chorda tympani nerve function in children: relationship to otitis media and body mass index.

OBJECTIVE/HYPOTHESIS: A relationship between acute otitis media and elevated body mass index has recently been reported. Intriguingly, it was postulated that this relationship may result from altered chorda tympani nerve function impacting taste sensation and eating habits. We sought to test this directly by measuring chorda tympani nerve function in children with and without a previous history of acute otitis media and to determine the relationship to body mass index. STUDY DESIGN: Retrospective cohort study. METHODS: Institutional research ethics board approval was obtained. Study participants included 142 children (5-18 years of age) who were recruited from an otolaryngology outpatient clinic at a tertiary academic pediatric hospital between May and August 2009. Children were excluded if they were not able to communicate effectively, younger than age 5, or had developmental disabilities. Body mass index was calculated and the history of previous otologic disease carefully elicited from the caregivers. Electrogustometric threshold, a validated measure of chorda tympani function, was obtained bilaterally in each child. Children were divided into cohorts based on the number of acute otitis media episodes, and electrogustometry thresholds were compared between cohorts. RESULTS: Electrogustometric thresholds were successfully obtained in all children. There was no significant relationship between chorda tympani nerve function and history of acute otitis media. Similarly, there was no significant association between the history of otitis media and body mass index. CONCLUSION: This study did not demonstrate any effect of previous acute otitis media history on chorda tympani nerve function. Furthermore, it did not demonstrate a relationship between acute otitis media and elevated body mass index. This is counter-evidence to the previous hypothesis that increasing acute otitis media is responsible for increasing childhood obesity through alteration in chorda tympani nerve function.