Intraoperative Cochlear Implant Reinsertion Effects Evaluated by Electrode Impedance.

OBJECTIVES: To assess the effect on impedance levels of intraoperative reinsertion of a cochlear implant (CI) array compared with matched controls. STUDY DESIGN: Retrospective patient review. SETTING: Cochlear implant center. PATIENTS: CI recipients in the Sydney Cochlear Implant Centre (SCIC) database who required intraoperative array reinsertion and matched controls. Exclusion criteria; known preceding meningitis or labyrinthitis ossificans; electrode array buckling; incomplete "final" insertion. INTERVENTION: Cochlear implantation. MAIN OUTCOME MEASURES: Impedance values measured intraoperatively, at switch on, 3 months, 6 months, and 12 months postoperatively were analyzed. The Generalized Estimating Equation (GEE) Model was used to compare cases with controls for each device, at each time point, and for each channel. RESULTS: Thirty-one reinsertion cases identified; six CI 422 arrays; 14 CI 24RE (ST) arrays, and 11 CI 512 arrays. No increase in impedance levels was found in the reinsertion cases when compared with their matched controls. The only statistical difference in impedance was seen in the CI 422 cohort at switch on with the reinsertion cases having lower impedances (p = 0.03). CONCLUSION: This is the first study to examine impedance values in patients who underwent intraoperative CI array reinsertion and to compare them with the impedances of matched controls. No significant increase found in impedances between our reinsertion cases and matched controls, suggesting the reinsertion did not result in any additional trauma or inflammation. This has implications for surgery both in routine cases such as a faulty electrode and also for future design of mechanisms for delivery of intracochlear therapies.

Balance in children following cochlear implantation.

OBJECTIVES: To assess the vestibular function of children who had unilateral and bilateral cochlear implants compared with a control group of otherwise healthy children who had not been implanted. STUDY DESIGN: Observational case-control study. METHODS: Posturography was carried out in the form of a Modified Clinical Test of Sensory Interaction on Balance using a Wii Balance Board and the Vestio App on an iPod Touch. Thirty children in total were tested, 10 children in each cohort. Results in the form of root mean square calculations were available for each child. RESULTS: Results showed a significant difference in the vestibular function of implanted children and the non-implanted control group (P < 0.05). As expected, children in all groups had more difficulty maintaining posture with their eyes closed on a compliant surface (P < 0.05). Thirty per cent of children with bilateral and 10% with unilateral cochlear implants were unable to complete testing. CONCLUSIONS: Our study demonstrates posturography as an inexpensive, easily operated tool that can be used to assess paediatric vestibular function. It showed a significant difference between the control group and the implanted groups. Further work prompted by this study will include interval post-operative testing to more accurately assess the effect that implantation has on vestibular function.

How we do it: Local anaesthetic cochlear implantation.

OBJECTIVES: To review a patient series of 16 cochlear implantations performed under local anaesthetic (LA), including a description of the centre's technique for this procedure. We also describe the application of a method for calculation of the potential morbidity/mortality avoided by using this technique. METHODS: Chart review of 16 patients' pre-operative medical and anaesthetic notes and calculation of predicted individual P-POSSUM Scores for operative morbidity/mortality. RESULTS: All 16 patients were implanted successfully with no significant complications. Age range was 26-92 years, with an average of 68 years. The patients' average predicted mortality score associated with a general anaesthetic (GA) was 8.6% and morbidity score was 58%. CONCLUSIONS: Our experience shows LA cochlear implantation to be a safe and effective procedure. It has the benefit of avoiding the operative mortality risk predicted by P-POSSUM Scores. Cochlear implantation is known to significantly improve quality of life for users. Our findings suggest a potential group of cochlear implant recipients considered 'unfit' for GA may be being denied access to this intervention or being exposed to additional risk.