Has this study found a new possible solution for hearing loss?
Hearing loss affects many people of all age groups and demographics around the world. Whether hearing loss is moderate or severe, people who struggle to hear can experience social isolation, discomfort and difficulty at school or work. Unaddressed hearing loss costs the world $750 billion globally in lost productivity and support every year, which makes it an enormous but often overlooked medical challenge.
Though the causes of hearing loss aren’t usually life-threatening, they take a huge toll on a person’s life. Common treatments for hearing loss exist, but in many cases, they don’t fully restore hearing. However, one new study published in the European Journal of Neuroscience suggests doctors may soon learn how to fully regenerate human hearing.
What Causes Permanent Hearing Loss?
There are several types of hearing loss. Conductive hearing loss occurs when a problem with the structure of the ear prevents sound waves from reaching the inner ear, where they’re converted into electrical signals and transmitted to the brain. Conductive hearing loss may be caused by fluid or wax build up or physical structures like bone growth or a tumor in the ear. Doctors usually treat this type of hearing loss through cleaning or surgical intervention.
Another type of hearing loss, sensorineural hearing loss is more serious. This occurs when the hair-like nerve cells in the inner ear become damaged, which can result from aging, disease, injury and exposure to loud noise, among other things. These cells convert sound into the electrical signals which will go to the brain for interpretation. If these important cells become damaged, they can’t perform their job.
Doctors struggle to treat sensorineural hearing loss because the cells cannot be repaired or replaced. Interventions to improve quality of life through hearing aids, telephone amplifiers and cochlear implants don’t restore hearing. Instead, they simply amplify sound to assist existing nerve cells. Furthermore, because people, on average, wait about seven years to seek treatment, it’s often too late to take helpful preventative measures.
Addressing sensorineural hearing loss is essential to solving hearing problems, since more than 90 percent of hearing loss is caused by damage to these sensory nerve cells. The new study by scientists at University of Rochester Medical Center aims to address this problem head on.
Is Hearing Regeneration Possible?
In mammals, damaged nerve cells in the inner ear never grow back, which means sensorineural hearing loss is permanent. However, this isn’t the case in all animals. Amphibians, reptiles and birds regenerate their hearing hair cells, so they never go permanently deaf. So what makes mammals different?
The key might lie in how mammals express, or block, the signals that tell new auditory nerve cells to grow. In the new study, scientists focus on an epidermal growth factor called ERBB2. These receptors activate nerve cell regeneration in birds. In mammals, these receptors exist but don’t get activated.
To activate ERBB2 signaling, the researchers used three methods: a virus that targets ERBB2 receptors, genetic modification and drugs known to activate the receptor. In mice, the researchers found that activating the ERBB2 pathway led to generation of new sensory hair cells as well as integration with the nerve cells needed to transmit signals.
These results suggest that ERBB2 may present a treatment path for permanent hearing loss. In the future, doctors may be able to treat sensorineural hearing loss by activating the receptors artificially and stimulating new cell growth.
What Does This Mean for People with Hearing Loss?
The results of the URCM study suggest a hopeful outlook for people with sensorineural hearing loss. Though scientists have not yet regenerated nerve hair cells in humans, they are making progress towards that goal.
It’s important to note that regenerating nerve cells can’t solve all issues with hearing loss. It won’t affect conductive hearing loss, and it also won’t be able to treat sensorineural hearing loss caused by problems with the auditory nerve or brain. However, ultimately, this treatment could improve quality of life for countless individuals.
The ability to regenerate hearing nerve cells successfully could restore hearing to people with mild hearing loss or potentially even deafness. For the millions of people suffering from hearing loss around the world, this news could be life-changing.