Download 13th International Conference on Cochlear Implants and Other
Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Document related concepts
Auditory system wikipedia, lookup
Audiology and hearing health professionals in developed and developing countries wikipedia, lookup
Olivocochlear system wikipedia, lookup
Sensorineural hearing loss wikipedia, lookup
Noise-induced hearing loss wikipedia, lookup
Hearing loss wikipedia, lookup
Transcript
S25-3 The effect of cochlear duct length and cochlear size on hearing outcomes in hearing preservation cochlear implantation 1,2 1 1 1 1 1 Kuthubutheen J. , Grewal A. , Symons S. , Nedzelski J. , Shipp D. , Lin V. , Chen J. 1 1 University of Toronto, Sunnybrook Health Sciences Centre, Toronto, Canada, 2University of Western Australia, School of Surgery, Perth, Australia Intro: Hearing preservation cochlear implantation relies upon the assumption of atraumatic insertion of the electrode. Whilst it is common to utilize a single length electrode for the majority of implanted ears, it is well known that there is variability in cochlear duct lengths within the population and even within the same individual. This variability may result in cochleae that are more or less suited to a particular length of electrode. Insertion depth may be related to the degree of electrode trauma and therefore hearing outcomes. The aim of this study is to determine if cochlear duct length is a relevant factor in determining outcomes after hearing preservation surgery. Methods: 56 adult patients undergoing hearing preservation cochlear implantation were reviewed. 35 patients received the Flex 31 electrode (31mm) and 21 patients received the Flex 28 electrode (28mm). Full insertion was documented through a round window approach in all patients. Preoperative high-resolution temporal bone CT scans reformatted in axial and oblique coronal planes were used to measure the basal turn of the cochlea (A value) and to measure the outer and mid-scalar lengths of the cochlear duct to 720 degrees. Postoperative plain XRs were done to determine degrees of insertion and number of electrodes within the cochlea. Pure tone average thresholds and speech discrimination at 6 months were compared between the two groups Results: The cochlear outer wall and mid-scalar lengths are significantly correlated with the A value measured in the oblique coronal plane (R=0.7 and 0.6 respectively, p< 0.05). Both measures of cochlear duct lengths were highly correlated (R=0.85) and normally distributed, consistent with temporal bone studies. The Flex 28 electrode had a greater mean insertion depth of 525 degrees and 11.3 electrodes within the cochlea compared to the Flex 31 electrode with 488.29 degrees and 10.9 electrodes. The shorter Flex 28 electrode also had a greater depth of insertion in larger cochleae. In addition, for the Flex 28 electrode, CNC word scores at 6 months were higher in larger cochleae (R=0.7, p< 0.05) but not for the Flex 31 electrode. Effects on hearing preservation rates will be presented. Discussion: This study demonstrates that standard radiological software can be used to measure the cochlear duct length and that the basal cochlear diameter is a predictor of cochlear duct length. The shorter electrode paradoxically had an overall greater depth of insertion and in larger cochleae, achieved a greater insertion angle and greater speech discrimination. This may suggest postoperative migration of the longer electrode despite full insertion. Conclusion: Cochlear duct lengths vary between individuals and longer electrode lengths may not necessarily result in deeper insertions or better outcomes, indicating the need for individualized electrode choice. Learning outcome: To discuss the role of cochlear size on electrode insertion and outcomes 479
