Sensorineural Hearing Loss
Ninety percent of all hearing loss is caused by things in life that are often unavoidable – exposure to loud sounds, getting older, infections and some medications.
Hearing loss can occur in a few different ways. It can occur from damage to the outer and middle ear (conductive hearing loss), from damage to the inner ear (sensorineural hearing loss) or from a mix of both.
Sensorineural hearing loss, or damage to the hair cells or nerve fibers of the inner ear that convert sound into electrical impulses, is the most common form – accounting for 90% of all hearing loss. The damage can be congenital (present at birth, often hereditary) or acquired later in life.
Currently there are no FDA-approved treatments to repair this sensory system. Frequency’s lead candidate, FX-322, is designed to regenerate hair cells lost to acquired SNHL.
A single loud event – firecrackers or standing too close to a speaker at a rock concert with unprotected ears – can cause hearing loss. At the same time, noise exposure can gradually damage the hair cells and nerve fibers over time.
Most of us are exposed to a lot of noise during our lifetime, and the risk of hearing loss is growing as the world gets louder.
Other causes of acquired sensorineural hearing loss include disease – viral infections, immune system problems, trauma – and toxic exposures to certain medications.
The Challenge of Treating Sensorineural Hearing Loss
We have two different types of hair cells in the cochlea – the inner hair cells and outer hair cells.
Outer hair cells sense and tune sound, as well as filter out any unwanted sounds. Inner hair cells convert mechanical sounds into electrical signals that are carried to the brain by the auditory nerve.
Today’s treatments for hearing loss – amplifying devices such as hearing aids – are limited in their ability to improve sound clarity, as they cannot replace the tuning and filtering of lost hair cells.