New research into the results and benefits of hearing aid use among patients diagnosed with unilateral sensorineural hearing loss (USNHL) has yielded encouraging results. USNHL, along with single-sided deafness (SSD), have recently been the subject of increased study and attention, as some 60,000 individuals acquire SSD annually in the United States (Hearing Journal. 2015; 68(2):20).
Although patients with USNHL and SSD share the common symptom of hearing loss in one of their ears (with normal hearing function in the other), the severity of the deficit in their affected ear can play a significant role in how the condition is addressed by a hearing health care professional.
A study published in the November/December 2017 issue of the Journal of the American Academy of Audiology, titled “Outcomes of Hearing Aid Use by Individuals with Unilateral Sensorineural Hearing Loss (USNHL),” delved into this topic and revealed reasons for optimism.
One focus was assessing “ … hearing aid outcomes for a group of individuals with USNHL with residual, aidable [sic] function,” according to the study's abstract. The Hearing Journal spoke with one of the authors, Jason Galster, PhD, senior manager of audiology research for Starkey Hearing Technologies in Eden Prairie, MN, about the study results and what it could mean for the future of managing this condition.
The condition's status as a “common audiologic problem” spurred Galster and fellow authors to look deeper into USNHL, he explained.
“We run into a lot of patients who have relatively normal hearing in one ear and a range of hearing loss in the other ear,” Galster said. “If you look at this topic in the clinical literature, what you'll see is a lot of focus on people who are candidates for CROS [Contralateral Routing of Signals] hearing aids. What motivated this article was the reality that we run into so many patients with an asymmetry that really aren't candidates yet for a CROS hearing aid.”
Galster went on to say that, for a variety of reasons among this particular subset of patients, “… wearing one hearing aid is really the more practical route to treatment.”
In the study, participants were fit with digital, behind-the-ear hearing aids coupled with custom ear molds. The researchers found that the use of hearing aids improved the quality of hearing for patients with USNHL. “We observed that hearing aid use by individuals with USNHL can improve the SNR [signal-to-noise ratio] loss associated with the interference of background noise, especially in situations when there is spatial separation of the stimuli and speech is directed toward the affected ear,” the conclusion noted.
Galster also offered practical recommendations for managing USNHL in patients who present with the symptoms.
“A child presenting with asymmetric hearing loss absolutely is a case that should not be overlooked,” Galster said. “It's the responsibility of the audiologist to interact with the family, with the child who is the patient, and with support services, whether it's the school system or otherwise. A child may appear to function quite well, but in dynamic classroom situations, there's a great amount of evidence to show that it can be a problem to not treat that hearing loss or compensate for it in the classroom. Among children, it needs to be treated as a priority.
“Similarly, among adults, it needs to be treated as a priority. But the lifestyle and situational needs of that adult patient really need to be factored in. I would urge any audiologist to consider any patient with asymmetric hearing loss as a candidate for a hearing aid. They should at least go through a trial to experience the benefits of a hearing aid and really opt out themselves if they don't realize the benefit. This is an ongoing challenge for clinical audiologists. It can be easier not to prescribe the hearing aid, but patients should be given the opportunity to undergo a trial.”
Galster also said that some of his more recent ongoing research involves examining outcomes for candidates whose unilateral hearing loss is significant enough to be considered SSD and merit the use of a CROS hearing aid.
One area focused on by Galster and other audiologists is the importance of addressing USNHL in children—even when only beginning to manifest mild symptoms of the condition at an early age.
For those who exhibit symptoms of USNHL, studies have shown that adding a hearing aid can help provide normal hearing to the affected ear. Meanwhile, patients with SSD are often candidates for CROS or Bone Anchored Hearing Aid (BAHA) devices, which differ from cochlear implants.
While implants can provide hearing function to the affected ear, they are also expensive, require surgical intervention, and introduce a somewhat unnatural, electrical form of hearing to the deaf ear. CROS or BAHA units help to improve functional hearing by rerouting sounds directed toward the affected ear and retransmitting them to the ear with normal hearing, albeit without restoring hearing function to the ear that is deaf.
Laurie Caracciolo, AuD of the Hearing Center of Plainview in Plainview, NY, explained how she and her colleagues test for a range of hearing loss, including instances where the deficit is asymmetrical. “Typically, we test for air conduction, bone conduction, speech testing and, in the case of an asymmetrical hearing loss, masking of the better ear,” Carraciolo said.
Lisa Christensen, AuD, audiology program manager at Cook Children's Health Care System in Fort Worth, TX, and the president-elect of the American Academy of Audiology, detailed some of the specific interventions and treatments for newborns and young children, while also pointing out that hearing loss can manifest as something of a “hidden disability” in children.
“Single-sided deafness and unilateral sensorineural hearing loss don't really worsen with age, but our understanding and ability to notice the hearing loss do,” Christensen clarified. “When a newborn fails his or her first hearing screening, we generally try to follow a guideline of ‘one, three, six,’ which are our early intervention guidelines. We do a newborn re-screening at one-month-old, diagnostic testing by three months, and aid or intervention by six months. When we do that, we see those kids who have either unilateral or bilateral hearing loss competing with their peers as they should if we can get that intervention by six months.
“It can be difficult for families to detect, even if it's in both ears,” Christensen said about hearing loss in newborns. “Think about the things that newborns do—they sleep and they don't talk or tell you that they can't hear you. It's why hearing loss is sometimes referred to as a hidden disability—because you don't see it.”
Although Caracciolo and her colleague at the Hearing Center of Plainview, Randi Lieberman, HIS, both agreed that the results of hearing aid intervention for patients with USNHL can vary between patients, they noted that the sooner after experiencing hearing loss one can address the condition with an amplification device, the better they tend to adjust. “If seen by an audiologist, their hearing aid is fit well, and they have clear, appropriate expectations, most patients typically do pretty well,” Christensen said.
“Results will vary per patient,” Lieberman said. “Patients fit with devices on one side and normal on the other will have a tough time hearing in stereo (equal in both ears). We have fit patients with a CROS unit; however, results vary with patients and how much work and effort they put into using the technology.”
“I have seen mixed results in trying to amplify a unilateral hearing loss,” Caracciolo added. “People who have had hearing loss for a long time have found ways to cope with it, and once they try to amplify it, they cannot get used to the amplified sound. Others who are newly diagnosed may have an easier time adjusting to amplification.”
Christensen also specified that some of these early interventions may begin slightly after the six-month mark, something she and her colleagues determine on a case-by-case basis.
“It's sometimes hard to tell a parent, ‘it's [the hearing loss] in one ear, but we need to act now,’ especially if it's a hearing aid,” she said. “If it's a unilateral loss and we can put a hearing aid on, we jump to that pretty quickly. If it's a BAHA, where we would need to utilize a soft band, then we sometimes will wait until that child is about 6 to 9 months old and sitting up well because that device has to sit behind the child's ear or close to the ear. If they don't have great head or neck control, the device can end up popping off.”
A key reason for pediatric audiologists being quick to intervene and begin managing the symptoms of USNHL has to do with the condition's effect on the child's communicative, social, and academic development.
“Some possible implications [of untreated USNHL] are speech and language delay, communication difficulties, difficulty learning language, social-emotional problems, quality of life effects, and academic and behavioral difficulties,” Caracciolo said.
Christensen added, “When children with unilateral hearing loss or single-sided deafness start school, that's when we really begin to see the effects of their hearing loss. We start to notice that when they're missing things in the classroom due to background noise, they're not learning to read well. And if a child is not learning to read well, almost everything else falls apart as well. There's been tons of research into unilateral hearing loss and the effects that it has on kids as they go through school.”
Christensen noted that more recent studies consistently show students with asymmetrical hearing loss to perform considerably worse than their peers in math and language skills, and are disproportionately placed in special education programs.
“By the time we see kids who are in school and all of these things start to fall apart, we could have headed them off had we started early with intervention. When we see kids with a straight unilateral loss, we are pretty quick to follow those ‘one, three, six’ guidelines. If it's single-sided deafness, that delays everything a little bit because of the limitation of devices we can use.”
Christensen stressed the importance of aiding those with USNHL or SSD before their hearing loss can negatively affect their social development and experiences. “When you think about being a middle school or high school-aged kid, if you're in a group where everyone is talking and you miss something or you're always the one not getting the joke, that's a big social stigma,” she said.
Christensen emphasized the particularity of hearing aids by comparing them to another common but less stigmatized corrective device—eyeglasses.
“Hearing aids are not as widely accepted as things like glasses,” she said. “They're the same—both are sensory needs—but we're all much more willing to put on a set of glasses than a pair of hearing aids. But unlike eyeglasses, hearing aids need to be finetuned a little bit more. The crazy thing is that something that I think might be very loud might not feel so loud to you. We have different perceptions in our brains, so it sometimes takes several visits with an audiologist to finetune things.”
Going forward, Galster reiterated the importance of literature making a distinction between patients with USNHL and SSD, especially considering new evidence to support the efficacy of hearing aid use among the former group.
“What we're talking about here are two very different patient populations,” he said. “The reality is that while, yes, the challenges that patients from each population face are similar, the treatment methods are quite different. There's one where you're looking at the prescription of a single hearing aid to the impaired ear and another [with SSD and the CROS or BAHA] where you're looking at a wireless, technical solution that's intended to overcome the physical blocking of sound that the head introduces.”
Summarizing the complexity of USNHL, Christensen said that while many come in hoping to put on a hearing aid like a pair of eyeglasses, the specific needs of each patient require additional adjustment.
“Occasionally a perfect fit does happen, but most of the time it's a process that does take a little bit more work,” she said.
Jason Galster, PhD
Lisa Christensen, AuD
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