OCT imaging of the human inner ear

Project Summary/Abstract A sudden drop in hearing in a previously healthy adult patient is a common patient presentation. Medical terms that are used to describe the various forms of this disorder include sudden sensorineural hearing loss, cochlear hydrops, Meniere’s disease, and autoimmune inner ear disease. However, the underlying pathophysiology is poorly understood. To date, post-mortem temporal bone histopathology and animal models have provided the best data about these conditions, and it appears that a relatively common finding is increased endolymph volume, termed endolymphatic hydrops. The link between endolymphatic hydrops and human hearing loss has not been established. Here we propose to use optical coherence tomography (OCT), an imaging technique based on the use of low-power light, to visualize the fluid compartments of the human inner ear. We have built a device that permits us to see inside the lateral semicircular canal and measure the relative amounts of endolymph and perilymph. We will characterize the normal endolymph-to-perilymph ratio in control subjects undergoing mastoid surgery for middle ear disease who have normal cochlear function. In addition, we will compare the endolymph-to-perilymph ratio in subjects with Meniere’s disease and vestibular schwannoma who are undergoing mastoid surgery to treat their disease. If our hypotheses are correct, the endolymph-to- perilymph ratio will be tightly regulated in normal controls but elevated in subjects with inner ear disease. Thus, this study is designed to validate the use of OCT for human inner ear imaging and to support the use of the endolymph-to-perilymph ratio as an outcome measure for clinical trials of new treatments for Meniere’s disease. This exciting technology may also offer new approaches to assessing outcomes of innovative treatments of hearing loss or vestibular dysfunction, such as hair cell regeneration or gene therapy.