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Research Aims to Reverse Noise-Induced Hearing Loss

In the future, insurers and employers could find themselves paying for the restoration of some claimants’ hearing instead of hearing aids.

Two research projects are aimed at fixing tiny, complex pieces of the inner ear to restore hearing.

One path to reversing hearing loss could come through a surgical procedure where doctors inject a fluid into the inner ear to stimulate the regeneration of the tiny hairs in the inner ear that transmit sound to the brain. The drug company Novartis is pursuing that project through researcher Hinrich Staecker, a professor at the University of Kansas Medical Center. Staecker said he’s hit the first phase of clinical trials, meaning that the method has proved effective in animals and he’s now gauging the safety and effectiveness of the treatment in humans. After this phase, it would need to undergo another round of testing with a larger patient population.

The other possibility for treatment comes through Gabriel Corfas, director of the University of Michigan’s Kresge Hearing Research Institute. Corfas is in the animal testing stage with a therapy that would target the synapses between the inner ear’s hair cells and the neurons that transmit sound signals to the brain. Corfas and his fellow researchers have shown that when they increase the level of the protein neurotrophin 3 in mice, they are able to regenerate the synaptic connections between hair cells and neurons.

Corfas and Staecker both said they aren’t sure yet just how effective the treatments could be – that is, whether they could bring hearing back to normal or only improve it marginally. Corfas said the Novartis research could have some limitations because the neurons that connect with the inner ear’s hair cells can often die after the cilia are damaged due to excessive noise.

Staecker said that’s true in small animals, such as mice, but not necessarily humans. Still, neurons can die for various reasons.

“In humans there is a disease related to the loss of neurons as well, so it’s all about picking your patient population properly,” he said.

While other types of common industrial injuries like back pain and rotator cuff tears can be treated, the assumption with hearing loss is that it can’t be reversed. In fact, Illinois’ workers’ compensation law is written with that presumption in mind, according to defense attorney James Gallen. That state’s workers’ compensation statutes, in Section 8(e)16, call for the payer to reimburse the claimant for “loss of hearing,” not the treatment of hearing loss.

So if, in the future, Corfas or Staecker’s research made it possible to restore hearing, some laws might need to be rewritten. And while payers might not need to pay for hearing aids for the rest of a claimant’s life, they might have to pay for surgery instead.

Today, surgery to install implants in the cochlea can sometimes restore hearing – but, like hearing aids, that involves a mechanical device and not the actual restoration of the biological processes that allow sound to make its way to the brain.

For Wisconsin defense attorney William Sachse, who was born with a hearing impairment, it makes sense to provide the procedure even if it is costly to the payer.

“It might be very expensive, (but) it might be very hard to look somebody in the eye and say, ‘Well, we’re not going to pay for that, I don’t care that you’re deaf, and you shouldn’t have the best technology,’” Sachse said.

Still, Sachse said, there would be benefits for payers in fixing hearing rather than reimbursing for hearing aids.

“We tend to pay for more than one set of hearing aids because they crap out and then you have to replace them, or there are technological advances,” he said.

Hearing loss claims tend to be tricky from the point of the defense, Sachse said. Regulations change from state to state, but like all work injuries, courts have to consider how much of the damage was the result of the claimant’s job.

The problem is that hearing loss tends to occur naturally as people age. Outside that, noise-induced hearing loss is relatively widespread in the American populace. According to a peer-reviewed article from National Institute on Deafness and Other Communication Disorders researcher Lisa Cunningham, about 15% of Americans from the ages of 20 to 69 have noise-induced hearing loss.

So when a hearing loss claim comes up, Sachse said, the defense has to consider whether part of that is due to age, or non-work activities such as attending loud concerts. Many hearing loss claims are filed years after the worker has stopped working for the employer, meaning that hearing test results can be lost or witnesses who could attest to the level of noise in the workplace are hard to find.

Another wrench in the works is the length of time some employees claiming industrial hearing loss worked for the employer. According to Sachse, defendants often have to rebut the plaintiff’s claim that the workplace was noisy. To do that, they might rely on testimony from a supervisor. But if they can’t find supervisors who were at the company for the entire time the claimant was, the defense can’t use that testimony to show that the workplace wasn’t noisy for the full period.

“Some of these guys worked for the employer 30 or 40 years,” Sachse said.

When considering so many variables that could contribute to hearing loss, he said, it becomes difficult to avoid subjectivity.

“Any time you get into a subjective situation like that I think the employee always gets the edge,” he said.

Regardless of the details of how such medical advances might affect the claims process, Gallen said the research represents a benefit for the workers’ compensation system as a whole.

“Ultimately that’s the way it should be,” he said. “I mean, we want to get the workers better, not pay them for their disability if we have a choice.”


Photo Courtesy of National Institute of Health


Article by: Ben Miller, workcompcentral