KidsMD Health Topics

Hearing Loss

  • Hearing loss is the full or partial inability to detect frequencies of sound. Boston Children's Hospital offers a Habilitative Audiology Program, a Deaf and Hard of Hearing Program , a Diagnostic Audiology Program, and a Department of Otolaryngology and Communication Enhancement to treat hearing loss, as well as a walk-in evaluation clinic.

    • Parents are typically the first to notice their child's hearing loss.

    • According to the National Institutes of Health (NIH), nearly 12,000 babies are born each year in the United States with a hearing impairment.

    • Without screening or testing, hearing loss could go unnoticed until your child is more than a year old. Hearing loss is more likely in premature babies and babies with respiratory problems who have required long-term use of breathing machines, those with previous infections, and those taking certain medications.

    • Early intervention and detection of hearing loss is necessary to prevent additional problems with speech and language development.

    • Some hearing problems are medically or surgically correctable if they are caused by middle ear fluid. Other hearing problems are treated with the use of hearing aids

    • If a hearing problem is found, your audiologist and pediatrician will arrange for your child to be seen by an otolaryngologist (ear, nose, and throat specialist) and will guide you to other services to help your child learn to communicate.

    How Boston Children's approaches hearing loss

    Boston Children's Deaf and Hard of Hearing Program cares for more than 500 children and their families each year. It's one of the country's largest, most comprehensive hearing-loss programs. The Deaf and Hard of Hearing Program's interdisciplinary team includes hearing and deaf professionals who are experienced working with children of all ages, with varying degrees of hearing loss. At Boston Children's, you'll see a multi-disciplinary team of speech-language pathologists, psychiatrists, ASL specialists, otolaryngologists and audiologists.

    Boston Children's Hospital 
    300 Longwood Avenue
    Boston MA 02115
     617-355-6460

  • What is hearing loss?

    It's easiest to break down hearing loss by type. The two most common types are sensorineural and conductive. Both types of hearing loss can be congenital (present at birth) or acquired.

    Sensorineural means a loss of function within the inner ear or with the connection to the brain. Factors that may cause this type of hearing loss include:

    • congenital (present at birth)
    • acquired
      • loud noise exposure
      • trauma
      • infections
      • damage from certain medications that can be harmful to the ears

    Conductive Hearing Loss indicates a problem in the outer or middle ear, in which sound waves are not sent to the inner ear correctly. Conductive hearing loss is the most common type of hearing loss in children and is usually acquired. Factors that may cause this type of hearing loss include:

    • congenital (present at birth)
      • anomalies of the pinna (the outside of the ear)
      • anomalies of the tympanic membrane (eardrum)
      • anomalies of the external ear canal
      • anomalies of the ossicles (the three tiny bones that deliver the sound waves to the middle ear)
    • acquired
      • excessive wax
      • foreign bodies in the ear canal, like beads or popcorn kernels
      • tumors of the middle ear
      • problems with the eustachian tube
      • ear infections, such as otitis media
      • chronic ear infections with fluid in the middle ear
      • perforation of the eardrum
  • Early intervention and detection of hearing loss is crucial; this will prevent your child from enduring additional problems with speech and language development. A healthcare team approach is normally used when a child is diagnosed with some degree of hearing loss.

    At Children's, team members include:

    • Audiologists. An audiologist specializes in the evaluation and management of hearing and balance problems in people of all ages. Audiologists are also involved with the fitting and management of hearing aids and other assistive devices.
    • Otolaryngologists. These physicians have special training in medical and surgical treatment for children who have disorders of the ear, nose, and throat.
    • Speech pathologists. A speech pathologist helps evaluate and manage speech, language, and hearing problems in your child.

    At Boston Children's, our diagnostic audiology team will:

    • monitor your child's hearing loss
    • provide counseling to you and your family regarding the hearing loss
    • recommend hearing aids and ways to maximize the use of residual hearing
    • refer your child for additional language or developmental assessments
    • direct you to community resources for educational or financial assistance
    • refer your child to the Habilitative Audiology Program to learn about the option of a cochlear implant if your child has a severe to profound hearing loss in both ears
  • Some hearing problems are medically or surgically correctable. Other hearing problems are treated with hearing aids and speech and language therapy.

    The three most common types of treatment are:

    • Use of hearing aids: These electronic or battery-operated devices can amplify and change sound. A microphone receives the sound and converts it into sound waves. Then, the sound waves are converted into electrical signals.

    • Cochlear implant:This is a surgically placed appliance that helps to transmit electrical stimulation to the inner ear. Only certain children are candidates for this type of device. Ask your child's physician for more information.

    • Training in ASL and lip reading

  • Most cases of deafness are caused by the dysfunction or death of cells in the cochlea, the snail-shell-shaped structure in the inner ear. The laboratory of Douglas Cotanche, PhD, formerly a researcher in Otolaryngology, was able to grow all the assorted cell types in the cochlea from just one source: neural stem cells. 

    Neural stem cells were first isolated from mice in 1998 by Evan Snyder, MD, PhD, formerly of Boston Children's Department of Neurology. Cotanche's team implanted the cells deep inside the sound-damaged cochleas of guinea pigs and mice. Six weeks later, the cells had migrated throughout the cochlea and formed satellite cells, spiral ganglion cells and Schwann cells, which make up the cochlea's nervous tissue, as well as the hair cells and supporting cells of the organ of Corti (the actual hearing organ). 

    The researchers couldn't show complete rebuilding of the cochlea, but they believe that with more time and more stem cells, most of the cochlea could be repopulated. The next step is to implant human neural stem cells in animals and test whether the new cochlear cells connect with the auditory nerve and the brain, and whether they respond to sound stimulation--in other words, whether they restore hearing.

    Gene-therapy trial will attempt to restore hearing in deaf mice

    In the Journal of Clinical Investigation, a team co-led by Jeffrey Holt, PhD, of the Department of Otolaryngology at Boston Children’s Hospital  demonstrated that two related proteins, TMC1 and TMC2, are essential for normal hearing – paving the way for a test of gene therapy to reverse a type of genetic deafness.  

    “This is the first time anything like this has been done,” says Holt.

    Learn more.

  • Breaking the silence

      Hannah enthusiastically reacts to new soundsWhile sitting across from each other at the kitchen table, Heidi Harrington asked her daughter, Hannah, "Where's Yoda?," to which the 6-year-old casually replied, "He's dead." In most situations, acknowledging the passing of a family hamster would have been sad, but Heidi and her husband, Jack, started crying tears of happiness. Their conversation took place shortly after Hannah's first "mapping" session to activate her new cochlear implant, and Heidi was testing how well Hannah could hear. "She understood us and answered perfectly—it was just unbelievable," says Heidi.

    Hannah inherited Waardenburg syndrome, a condition that can cause mostly benign symptoms, like a white streak of hair, differently colored eyes or webbed toes. But Hannah suffered the most serious symptom—hearing loss. She had hearing problems from birth, so learned to communicate via sign language and could understand some speech with the help of powerful hearing aids. But the textured, layered world of hearing was lost to her, and over the years, her hearing worsened. Last year, it became clear she wasn't hearing at all, and her grasp of language started to slip away.

    This turn of events had a silver lining for the Harringtons, since it meant that Hannah now qualified for a cochlear implant, a device that's been restoring the hearing of people who are deaf for nearly two decades. Hannah hadn't been "deaf enough" to be a candidate before she turned 6. Since the surgery to place a cochlear implant is major and cuts off the patient's residual ability to hear, it's only performed when hearing aids don't help at all.

    By the time Hannah qualified, she was older than the ideal implant candidate. "Hearing is a 'use it or lose it' phenomenon," says Hannah's surgeon, Greg Licameli, MD, director of the Cochlear Implant Team at Boston Children's Hospital. Research shows that children who receive implants when they are as young as 1 make greater strides in their language abilities than older children. But Hannah was still eligible, since she'd developed some language skills before losing her hearing and was therefore more likely to regain them. She also passed the implant team's rigorous evaluation process, in which audiologists, speech pathologists, psychologists, developmental pediatricians and surgeons all weigh in on a candidate's likelihood of success. "If Hannah never had hearing and didn't have good access to rehabilitation post-surgery, we wouldn't have been optimistic and probably wouldn't have done the surgery," says Licameli.

    TURNING ON SOUND

    Cochlear implants have two parts: an external microphone, sound processor and transmitter system, and the receiver and electrode system that gets implanted in the head behind the ear. Whereas hearing aids amplify sounds, implants stimulate the hearing nerve directly by receiving sound from the outside environment, converting it into digitized signals and transmitting those signals to the electrodes in the cochlea, the spiraled cavity of the inner ear. While the brain learns to recognize the signals as sounds, the patient doesn't experience it as hearing, per se, especially not at first.

    "Many people say it feels more like a pressure or a sensation," says Lynne O'Brien, Hannah's audiologist. "Then it turns into a squawking noise that some kids say sounds like chickens. At first, everything sounds like one big barnyard."

    After Hannah's surgery, when she had devices implanted behind and in her right ear, she came back to Children's to get them turned on. This happens in several stages, during which O'Brien gradually exposes Hannah to sounds and maps her processor to pick up softer and more wide-ranging noises. The first session can be incredible for the patient, her family and the clinicians. "It's amazing to see that moment when it's activated, especially with kids who've never even heard a beep before," says O'Brien. "Children point to their ear and their faces light up with surprise."

    Sometimes, when the microphone gets switched on, all the people in the room—especially the parents—start crying when they see the child's expression when they hear. "We have to be careful because that can be scary for the child, since the very first thing she hears is the sound of everyone sobbing."

    Over the years, doctors have taken this into account and adjusted the turning-on process. "As technology improves, we have the capability of turning it on bit by bit so kids aren't as overwhelmed," O'Brien says. Still, hearing for the first time—or hearing in a whole new way—can be a shock. "The ride home is strange for lots of kids, as they hear the wheels on the pavement, the wind against the windows, the radio, people eating and talking all at once," says O'Brien. "They suddenly have a whole new sense and it's so strange for them, with all this sound coming in and them not being able to make sense of it yet."

    The turning-on, or mapping process, is painstaking, as audiologists carefully test patients' hearing range and adjust the transmitter for two-hour sessions, every few months. One time, a patient of O'Brien's came running back after a session, upset that the device was defective and making thumping noises. "It turned out it was his footsteps that he was hearing for the first time," she says. "Sounds can drive people nuts until they can identify them and learn to put them in the background."

    Ever since the day Heidi first tested Hannah's implant (Hannah said through sign that the squawking sounded like monkeys), her parents haven't been able to stop trying out her new abilities. "It's just fascinating to watch her discover the hearing world," says Heidi. When Hannah had Rice Krispies for breakfast a few months ago, she erupted in shouts of 'Pop! Pop!,' simply amazed that her that cereal bowl was making noise. So far, she's been through four mapping sessions, and each time she lights up in delight when she hears sounds she didn't know existed. In her most recent session, she heard high-frequency sounds like "f" and "sh" for the first time. "The subtleties of language are coming to her now," says Heidi. "Every week, we're seeing something different. She can tell you the difference between a plane, helicopter and blimp without seeing them. She's so excited about hearing and is really having fun."

    Right now, Hannah can't localize sound well, so she still searches for where sounds come from. This brings with it its own amusements: Recently she was looking down at a pool of water to watch fish swimming while noisy black birds flew overhead. "She heard the 'caw!' while staring at the fish and we could see her trying to mentally process—'Do fish make that noise?'" says Heidi.

    A SOUND DECISION

    Cochlear implants used to be a highly contentious topic among members of the deaf community, as many took offense at the idea that restoring hearing is "correcting" something they don't see as a disability. But according to Licameli, the controversy has waned over time, as the benefits of implants have become evident. "We've been able to demonstrate that it really does work," he says. "Now we have deaf parents come to us with their deaf child to explore implants for the child. Ten years ago, that never would have happened."

    For Jack and Heidi, the decision was clear-cut. "Hannah was missing so much, we needed to go to the next step," Jack says. Hannah is among the 98 percent of deaf children who have hearing parents; while the Harringtons all used sign language, the fact that she can talk to her brother, Jake, and to her parents, has changed the family dynamic drastically. "Hannah's always been social, but now she constantly has something to say and loves telling us stories," says Heidi. "There was a day last week when I said, 'Child! Can you just be quiet for a minute?' and I couldn't believe what I said. For years, she wasn't talking at all. Her ability to participate in the world has dramatically improved because people can understand her and she can understand them."

    Looking ahead, Hannah is a good candidate for a cochlear implant on her left ear and will be evaluated this winter. Generally, the second implant happens a year after the first, to give patients time to adjust. The second one would give her a better ability to differentiate sounds in noisy situations and the ability to hear in stereo, which helps in localizing noises. "We can't wait to get the other side done, if the first is any indication," says Jack. "Her speech clarity has improved beyond what we could have imagined, and she's telling us in every way that she wants it." In the meantime, Hannah is taking advantage of modern technology. Her device comes with an iPod input, and she can't get enough of the song "Who Let the Dogs Out?" by the Baha Men. "She loves music and glows when we play it," says Jack. "It's one of her favorite things."

    "We do a lot of things in medicine that affect the quality of life, but this is life-changing," says Licameli. "That's the reason I enjoy it. I'm lucky to do it."

    Heidi feels lucky too. "When I was a kid, the scariest thing was the thought of going blind or deaf," she says. "But deaf people have options now. There are so few true miracles in this world. This is one of them."

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