Cochlear Synaptopathy to Explain Hearing Loss

Cochlear synaptopathy is defined as the loss of nerve cells connected to the cilia. Nerve cells associated with cochlear synaptopathy are used to transmit nerve impulses (electrical signals) from the cilia to the brain. An important thing to note about cochlear synaptopathy is that it is an early marker of age-related hearing loss (presbycusis) and noise-related hearing loss. In fact, animal models have shown that damage to the nerve cells occurs even before the loss of cilia. It’s also interesting to note that the main role of nerve cells affected by cochlear synaptopathy is to allow optimal listening in noisy environments and group situations. This discovery is all the more important because these are generally the first symptoms reported in cases of presbycusis and noise-related hearing loss.

Traditional hearing assessments, such as pure tone audiometry (audiogram), are not designed to detect cochlear synaptopathy. Cells affected by cochlear synaptopathy work only when the volume reaches a certain level, that of a conversation. However, pure tone audiometry only assesses the lowest volumes at which certain sounds can be heard.

Other tests measure the electrical activity of the hearing system. These tests are used, among other things, to estimate the hearing thresholds of newborns. Currently, these tests are not accurate enough to quantify the nerve cell damage associated with cochlear synaptopathy.

While we currently lack the tools to measure this condition, researchers around the world are actively working on it.

The damage to nerve cells from cochlear synaptopathy is irreversible. Of course, the ideal solution would be to regenerate the lost cells. While research is underway to develop such a treatment, we likely won’t see medications on pharmacy shelves any time soon.

That said, hearing health professionals do have treatment options to address the listening difficulties caused by cochlear synaptopathy. Thanks to the latest sound processing technologies, hearing aids can partially compensate for the lost cells. Communication strategies (e.g. avoiding ambient noise, getting closer to the other person, having good eye contact with the other person, etc.) can also be an effective solution.

If necessary, it is important to consult an audiologist, who will guide you to the best possible treatment option.