Choice of Ear for Cochlear Implantation: The Effect of History and Residual Hearing on Predicted Postoperative Performance

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Abstract
This study used mathematical formulas predicting cochlear implant outcomes to investigate the effects of implantation in the poorer ear on postoperative speech recognition. Retrospective cohort study with mathematical and statistical analyses. This study used the University of Iowa formula for predicting outcomes derived from implantation of the better ear on the basis of duration of deafness and preoperative speech understanding, applying this predictive model to a cohort of patients undergoing implantation in the poorer ear at The Johns Hopkins Medical Center. Tertiary referral center with active cochlear implant program. Postlingually deafened adults (n = 58) with preoperative Central Institute for the Deaf sentence scores less than or equal to 40%. Cochlear implantation with all three Food and Drug Administration–approved devices. Postoperative monosyllabic word recognition scores and correlations between actual and predicted results. There was good statistical correlation between the predicted postoperative performance using the University of Iowa formula and the actual performance of our cohort of patients undergoing implantation in the poorer ear (r = 0.50, p < 0.0001). In addition, as a population, our cohort had a mean postoperative consonant-nucleus-consonant word score of 41.8%, which was statistically the same as that predicted by the University of Iowa formula (43.6%). The postoperative performance of cochlear implant patients is most closely correlated with duration of deafness. However, our results indicate that this measure may not be ear specific and is more reflective of the total auditory receptivity of the patient. These observations help to form guidelines for choice of ear for implantation.