Bioengineering Devices for the Treatment of Hearing Dysfunctions

  • Samuel Mark Flaherty

    Student thesis: Doctoral Thesis

    Abstract

    Approximately 466 million people, as of 2020, suffer with hearing loss of some degree (Deafness and hearing loss, 2020). Ranging from mild to severe, auditory complications can affect one’s ability to communicate, learn and interpret environmental stimuli.

    This work looks to provide experimental findings to further understand how the bioengineering of hearing devices can offer auditory rehabilitation to patients with sensorineural, conductive and mixed hearing loss. We explore the fundamental issues with passive intracochlear drug diffusion and the inability to administer drugs to the most apical regions of the cochlea without external assistance. We used sodium salicylate, which inhibits the cochlear amplifier, to determine the path of diffusion by recording compound action potentials thresholds across a wide frequency range in guinea pigs. We conclude that passive diffusion of an arbitrary substance through the round window membrane (RWM) leads to the formation of large substance concentration gradients along the cochlea.

    It is known that mechanical stimulation of the RWM, at frequencies similar to that of incoming sound, excites the cochlea. To further explore the efficiency and mechanism of round window stimulation, we designed mechanical displacement probes with different diameters, that partially occlude the round window membrane, to determine cochlear stimulation efficiency.

    We conclude that round window stimulation can be optimised for maximum cochlear excitation and without the requirement for ossicular chain mobility. Methods of drug delivery to the entire cochlear spiral are limited. We describe a novel method of cochlear drug delivery, by means of inaudible RWM micro vibrations, which enhance drugperilymph mixing. We provide a proof of concept that vibrating the RWM at a low frequency, enhances intracochlear drug distribution without impairing hearing.
    Date of Award2020
    Original languageEnglish
    Awarding Institution
    • University of Brighton
    SupervisorAndrei Lukashkin (Supervisor), Ian Russell (Supervisor) & Victoria Lukashkina (Supervisor)

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