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The Impact of the Auditory and Visual Environments on Balance in Children with Bilateral Vestibular Loss and Cochlear Implantation

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The Impact of the Auditory and Visual Environments on Balance in Children with Bilateral Vestibular Loss and Cochlear Implantation The Impact of the Auditory and Visual Environments on Balance in Children with Bilateral Vestibular Loss and Cochlear Implantation by Nikolaus Ernst Wolter A thesis submitted in conformity with the requirements for the degree of Master of Science Institute of Medical Sciences University of Toronto © Copyright by Nikolaus E Wolter 2014 The Impact of the Auditory and Visual Environments on Balance in Children with Bilateral Vestibular Loss and Cochlear Implantation Nikolaus Ernst Wolter Master of Science Institute of Medical Sciences University of Toronto 2014 Abstract Vestibular impairment is common in congenital sensorineural hearing loss yet children are remarkably able to remain upright. To understanding how these children compensate for their bilateral cochelovestibular loss (BVL) we investigated the effects visual and auditory virtual environments in children with BVL and bilateral cochlear implantation (CI), ages 8.5-17.9 years on balance. Children with BVL had significantly impaired balance compared to typically developing children. Body movement was greater in children with BVL balancing. Children with BVL relied on vision to a greater extent than their typically developing peers. Moving objects in the environment did not alter balance in either group. Balance and postural control improved in children with BVL when CI were on. Children with BVL rely on vision and auditory input through CI in order to balance but this does not restore balance to normal levels. Novel methods are required to reestablish vestibular-type input in this vulnerable population. ii Acknowledgments The completion of this work has depended on the support, guidance and kindness of a tremendous number of people. I cannot adequately express the debt of gratitude I have to all of you for your countless hours of support. Please accept my sincerest thanks with a special thank you to: My research supervisor, Dr Karen Gordon, for guiding me through this process, for making me a more critical thinker, and helping to establish the foundation I will use to continue to answering my many questions for the rest of my career. Thank you to Salima, Melissa, Stephanie and Morrison. I expected to meet a number of highly intelligent people during the pursuit of my Masters degree but I did not expect to meet such genuinely good and kind people and to make such good friends. My clinical supervisors, Dr Blake Papsin and Dr Sharon Cushing, it is not easy to express the debt of gratitude I owe you both. Dr Papsin, thank you for inspiring me to do this and pushing me to make more of myself than I ever thought possible. Dr Cushing, I could not have done this without you, thank you for your tireless support and encouragement and for being behind me every step of the way. You have both been incredible mentors and role models and you are both examples of the kind of surgeon and scientists I aspire to be. The TRI CEAL and iDAPT team, thank you Dr Campos for your patience, guidance, and kind words. You have been an amazing source of information, advice and support and I feel very fortunate to have met you. Thank you also to your team: Susan, Alison, and Bruce. Without their support none of this work would have been possible. My family, thank you to my mother and father for their encouragement and kind words throughout my education. Finally, thank you to my wife, Jennifer. You have been the source of all the good that I have done since I first met you. Thank you for making me better, for picking me up, dusting me off and pushing me back into the ring. Thank you for everything.O. iii Table of Contents Table of Contents Acknowledgments................................................................................................................. iii Table of Contents ...................................................................................................................iv List of Tables .........................................................................................................................vii List of Figures .......................................................................................................................viii List of Appendices .................................................................................................................. x List of Abbreviations...............................................................................................................xi Chapter 1................................................................................................................................ 1 1 Introduction.................................................................................................................... 1 1.1 Research Questions ............................................................................................................. 1 1.2 Background ......................................................................................................................... 2 1.3 Research Objectives ............................................................................................................ 6 1.4 Anatomy and Physiology of the Peripheral Vestibular System ............................................. 7 1.4.1 Vestibular Reflex Pathways.................................................................................................. 11 1.5 Integration of Vestibular Information ................................................................................ 14 1.6 Development of Postural Control ...................................................................................... 16 1.7 Methods of Assessment of Balance Function in Children ................................................... 20 1.7.1 Posturography...................................................................................................................... 21 1.7.2 Imaging Measurement Techniques...................................................................................... 21 1.7.3 Assessment of Balance and Motor Control in Children ....................................................... 23 1.8 Assessment of Balance in Real-World Environments.......................................................... 24 1.9 Cochlear Implantation and Vestibular Function ................................................................. 26 1.10 Balance in Children with BVL and Bilateral Cochlear Implants............................................ 29 1.11 Summary........................................................................................................................... 32 Chapter 2.............................................................................................................................. 34 2 Methods ....................................................................................................................... 34 2.1 Overview........................................................................................................................... 34 2.2 Participants ....................................................................................................................... 34 2.3 Subjective Assessment of Static and Dynamic Balance Function: BOT-2 Balance Subtest ... 36 iv 2.4 Objective Methods of Static and Dynamic Balance Function .............................................. 37 2.4.1 Motion Capture Analysis...................................................................................................... 37 2.4.2 Force plate Posturography................................................................................................... 38 2.5 Stimulus Environment: Street Lab Visual Dome ................................................................. 41 2.6 Testing Protocol................................................................................................................. 42 2.7 Data and Analysis .............................................................................................................. 44 Chapter 3.............................................................................................................................. 47 3 Results.......................................................................................................................... 47 3.1 Validity and Reliability of BOT-2: Balance Subtest in Detecting Balance Dysfunction in Children......................................................................................................................................... 47 3.1.1 Inter-Rater Reliability ........................................................................................................... 47 3.1.2 Known Group Validity .......................................................................................................... 48 3.1.3 Convergence Validity ........................................................................................................... 52 3.2 Impact of Vision on Balance in Children with BVL .............................................................. 68 3.2.1 Does Vision Play a Greater than Normal Role in Balance in Children with Bilateral Cochleovestibular Loss than their Typically developing Peers?........................................................ 68 3.2.2 Does the Visual Environment Affect Balance in Children?................................................... 76 3.3 The Impact of Audition on Balance in Children with BVL.................................................... 82 3.3.1 Impact of Restoration of Hearing Through Bilateral Cochlear Implantation on
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