Speech perception outcomes for cochlear implantation of children vary over a wide range, and it is hypothesized that central pathologic states associated with certain causes of hearing impairment account for a substantial part of the variance.
A retrospective analysis was carried out to ascertain the relationships between speech perception, etiologic factors, and central pathologic states as indicated by preoperative delayed motor milestones and/or cognitive delays.
Data were obtained from the pre-and postoperative records of patients attending a hospital cochlear implant clinic.
Results for 75 consecutive patients up to age 5 years who underwent implantation were included in the study.
Patients received a 22-electrode cochlear prosthesis and were seen by the clinic for regular tune-up and assessments. Home-and school-based habilitation was recommended by the clinic.
Speech perception measures were classified on a five-point scale to allow for different evaluation procedures at different ages and developmental stages.
The incidence of motor and cognitive delays were fairly evenly spread across etiologic factors, except for cytomegalovirus, which had a much higher than average incidence. Children with motor and/or cognitive delays were significantly slower than other children in the development of speech perception skills after implantation. Etiologic factors did not have a statistically significant effect on speech perception outcome.
It is likely that central pathologic states account for a substantial part of the variance among children using cochlear implants. Specific indicators of central pathologic states should be used to assess a child's prognosis in preference to less specific information based on etiologic factors alone.
Department of Otolaryngology, University of Melbourne, Victoria, Australia
Supported by the Bionic Ear Institute, the National Health and Medical Research Council of Australia project grant No. 970257, and the Cooperative Research Centre for Cochlear Implant, Speech, and Hearing Research.
Address correspondence and reprint requests to Dr. Peter Blamey, Department of Otolaryngology, University of Melbourne, 384–388 Albert Street, East Melbourne 3002, Australia.