Profiles of AEVs for intra- and post-operative integrity test measurements in young children with the Nucleus mini 22 cochlear implant.
Cochlear implantation of young children (<5 years of age) places additional demands on the implant team when compared to older children and adults. For these young children, it is essential to have integrity testing (IT) available to objectively assess the function of the internal device. Unfortunately, very few publications are available which document normal working ranges for IT. Thus the aim of the present study was to establish intra- and post-operative normal ranges for the averaged electrode voltage (AEV) which can be used in the clinical environment to assist in child management. As part of the routine protocol in Nottingham, IT was performed intra-operatively and 2 or 5 years post-operatively in common ground (CG) and pseudo-monopolar 1 (MP1) modes of stimulation on 30 children. All the children were implanted with the Nucleus mini 22 device. Normal ranges were calculated (mean +/- 1 standard deviation (SD)) for both intra- and post-operative measurements. In addition, the post-operative percentage changes in AEV amplitude were calculated for the 2-year and 5-year data groups. Data were excluded from calculations if an electrode was known or suspected to be faulty by visual examination of the AEV profile by an experienced observer. The results demonstrated that the profile of the AEV across the electrode array was preserved between intra- and post-operative recordings, although the amplitude of all AEVs decreased post-operatively. The percentage decrease (mean +/- SD) in (i) CG after 2 years was 69 (+/-16%), (ii) in CG after 5 years was 77 (+/-15%) and (iii) in MPI after 2 years was 35 (+/-1%). IT is a valuable objective tool to assess device function, in particular for young children. Normal AEV ranges are presented which can be used in the clinical environment to aid interpretation of IT performed intra- and post-operatively for CG and MP1 modes. Test data validate the implementation of normal ranges. Electrodes whose values of AEV amplitude fall outside the range should be investigated further.
Garnham
J
J
Medical Physics Department, Queen's Medical Centre, Nottingham, UK.
Marsden
J
J
Mason
S M
SM
D002675:Child, Preschool; D019929:Cochlear Implantation; D003638:Deafness / Q000175:diagnosis / Q000601:surgery*; D004566:Electrodes; D004868:Equipment Failure; D005260:Female; D006320:Hearing Tests / Q000379:methods*; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D011182:Postoperative Care / Q000592:standards*