Archived Webinar: Understanding Cases of Tinnitus with a Normal Audiogram: Is Hearing Loss Undetected with Brandon Paul – June 9th, 2020

Aired: Tuesday, June 9th at 12 pm ET

Speaker: Brandon Paul, PhD., Sunnybrook Health Sciences Centre

ABSTRACT: The majority of individuals with subjective chronic tinnitus exhibit shifts in the clinical audiogram that signal a degree of hearing loss. These observations support the idea that damage to structures in the ear precipitate a cascade of neuroplastic changes in the brain that give rise to the sensation of phantom sounds. However, 10–15% of individuals with tinnitus have normal hearing thresholds in both ears up to 8 kHz.

This presentation will consider potential reasons that some individuals with tinnitus have hearing thresholds within normal limits. For instance, audiometric shifts may be present but are missed by conventional testing, or damage may have occurred to sensory cells in a manner that does not affect thresholds. An emphasis will be placed on the topic of cochlear synaptopathy, a form of “hidden hearing loss” describing damage to synaptic connections between inner hair cells in the cochlea and auditory nerve fibers. The webinar concludes by describing physiological measures that may reveal synaptopathy, as well as the hurdles that remain before these tests can be used in clinical practice.

Learning points

  1. Standard audiometry may miss threshold shifts that are present in tinnitus sufferers, namely at frequencies above 8 kHz, or at several interoctave frequencies.
  2. Cochlear synaptopathy, or “hidden hearing loss,” may be present in individuals who have normal audiograms (even to 16 kHz) but chronic tinnitus.
  3. Detecting cochlear synaptopathy has proven difficult in humans, and thus the relationship between tinnitus and synaptopathy is unresolved.

Speaker: Brandon Paul is a Postdoctoral Fellow at Sunnybrook Research Institute and the Department of Otolaryngology within Sunnybrook Health Sciences Centre in Toronto. His research interests concern tinnitus, cochlear implant outcomes, cognitive consequences of hearing loss, and neuroimaging using electroencephalography (EEG). His research has been funded by the Natural Sciences and Engineering Council (NSERC) of Canada, and the American Tinnitus Association.