FEATURE
cochlear implant in children
An Interview with DR. KAREN
D
r. Karen Gordon is an Audiologist and the Director of Research in Archie’s Cochlear Implant Laboratory at The Hospital for Sick Children. She is an Associate Professor in the Department of Otolaryngology, and a Full Graduate Faculty Member in the Institute of Medical Science (IMS) at the University of Toronto. She is also affiliated with the Department of Speech Language Pathology. Dr. Gordon became the inaugural recipient of the Bastable-Potts Health Clinician Scientist Award in Hearing Impairment in 2014. She is presently examining ways to improve auditory development and hearing for children who are deaf by promoting binaural hearing with auditory prostheses including bilateral cochlear implants.
Please describe your education background and training. I completed my Bachelor of Science at the University of Toronto in 1991 and then received a clinical degree in audiology at Northwestern University in Evanston, Illinois in 1993. I worked as an audiologist at the Hospital for Sick Children for almost four years before starting my graduate studies through IMS at the University of Toronto in 1998. Those were wonderful and fun years as I became a mom (two daughters) and set up what is now Archie’s Cochlear Implant Laboratory at SickKids. How did you get involved in cochlear implant research and what did you find most appealing in this area? I was an audiologist in the cochlear implant program before going back to graduate school. At that time, cochlear implantation in children who were deaf was fairly new. There were so many questions about these unique devices and about how children who received one cochlear implant might learn to listen and communicate. 12 | IMS MAGAZINE SPRING 2016 SENSORY SYSTEMS
Please give us some insight on unilateral and bilateral cochlear implant in children, and your research findings. In my PhD studies, I explored developmental changes along the auditory pathways in children who received one cochlear implant. We discovered changes in brainstem and thalamo-cortical function that were time-locked to the beginning of cochlear implant use. Rates of change in the auditory brainstem were remarkably similar to those in normal hearing children over the first years of life, indicating that development at this level of the auditory pathways requires stimulation. By contrast, changes in thalamo-cortical activity were more variable and dependent upon the age at implantation. It became clear that the auditory cortex was vulnerable to reorganization during a period of bilateral deafness which affected cochlear implant use. We wondered whether the auditory brainstem, which plays an important role in integrating sound information from our two ears, could be vulnerable to reorganization by unilateral stimulation and whether there were more central effects in the auditory cortex. At the same time, we were seeing
GORDON By Yekta Dowlati
that children using one cochlear implant were hearing and developing spoken language but that they were struggling in situations with multiple sounds and voices. This was due, in part, to a lack of hearing from both ears. We therefore embarked on studies of children provided with two cochlear implants. We compared children who had used one cochlear implant for months to years before receiving a second in the non-implanted ear (sequentially) to children who received bilateral cochlear implants simultaneously. The data revealed significant asymmetries in development along the bilateral auditory pathways in children implanted sequentially with a long delay. This sets up an “aural preference” for the first implanted ear, disrupting binaural hearing. By contrast, children implanted bilaterally with limited or no delays show more normal auditory development. What are the main impacts of your research work? Our early work revealed effects of deafness on the immature auditory system and the effectiveness of cochlear implant use to initiate development in the auditory