When Hearing Is Lost, Surgery May Be Treatment of Choice

Special education, loss of productivity, and the need for medical treatments associated with hearing loss cost an estimated $30 billion a year, yet hearing loss seems well outside the embrace of mainstream medicine.

For example, when Donna R. Halloran, M.D., an assistant professor of pediatrics at Saint Louis University School of Medicine, analyzed results of hearing screenings done in pediatricians’ offices she found that 59% of children who failed the hearing test had no further evaluation.

Dr. Halloran said this seeming indifference is probably a cultural phenomenon. “I think that pediatricians doubt the value of the test and prefer to rely on their own history and physical,” she said. She and her colleagues reviewed 1,061 hearing screenings done by academic and private practice pediatricians in Alabama.

Her findings, which were published in the October issue of Archives of Pediatrics and Adolescent Medicine, review data on routine childhood screenings that are typically done at age three. “I think a better approach would be to screen at age 4 and to use a hearing loss threshold of 25 decibels,” she said.

The screening exams in her study used a cutoff of 20 decibels, which reflects an old screening guideline that the American Academy of Pediatrics changed to 25 decibels in 2003.

To put that into perspective, a soft whisper is 30 decibels, ordinary conversation is 60 decibels, and a jet engine is 140 decibels.

Once hearing loss is identified, further evaluation is required to identify the type of hearing loss-conductive, sensorineural, or mixed-before there can be an effective intervention.

Conductive hearing loss, for instance, can be caused by something as simple as impacted cerumen. Once the earwax is removed the problem is corrected.

On the other hand, otosclerosis, defined as the progressive conductive hearing loss caused by the abnormal growth of bone in the middle ear, often requires stapedectomy, a complex procedure in which the surgeon bypasses the diseased bone with a prosthetic device that allows sound waves to be passed to the inner ear.

This surgery carries a small risk of worsening hearing rather than improving it, but results are usually very good, said S. Thomas Westerman, M.D., an associate clinical professor of otology at Drexel University in Philadelphia.

In between these two procedures is tympanoplasty, or surgical repair of perforated eardrum. There are a wide variety of techniques used for tympanoplasty but most “patch” the tympanic membrane with tissue or tissue matrix.

Unilateral/asymetric hearing, which may be accompanied by dizziness or tinnitus, may be caused by vestibular schwannoma, which is also known as an acoustic neuroma. This condition requires removal of the tumor either by surgery or radiation. If the tumor is very small, hearing can sometimes be preserved at the level it was before surgery.

But the most common type of hearing surgery is a cochlear implant, and it is this surgery that is a driving force behind the movement for early identification of congenital hearing loss.

In the words of the 1995 NIH Consensus Statement on Cochlear Implants in Adults and Children, “Cochlear implantation improves communication ability in most adults with severe to profound deafness and frequently leads to positive psychological and social benefits as well. Currently, children at least two years old and adults with profound deafness are candidates for implantation.”

According to the NIH consensus advisers, children who have cochlear implants can improve spoken communication even if they “lost their hearing prelingually; moreover, there is evidence that the benefits derived improve with continued use.”

The NIH advisers’ statement suggests that cochlear implants are most effective when implanted in children before age six, but pediatric audiologist Gail Whitelaw, Ph.D., said surgery should be considered as early as age one if a baby is not getting good results with hearing aids.

Whitelaw, who is director of clinical instruction and research at Ohio State University’s department of speech and hearing science, is president of the American Academy of Audiology.

Ideally, she said, children should be fitted with hearing aids before six months, so that “we can begin to assess if we are getting good responses.” Implants, she said, “are for children who don’t get a good response with hearing aids.” These are typically children with profound sensorineural bilateral hearing loss, meaning more than 90 dBHL.

This can be difficult to assess when the child is an active baby, who may frequently dislodge the hearing aids or simply pull them out. “It’s a real challenge,” said Whitelaw, “but when the hearing aid is working, you can see it in the baby’s face. You will see a reaction to sound, it will startle them, or see curious looks.”

On the day Whitelaw was interviewed, she was evaluating a 15-month-old boy. “We’ve been giving hearing aids a college try, but I think we are only getting a limited benefit,” she said. “This family is now struggling with the decision about surgery. They are afraid of surgery, but they recognize that we are not seeing progress.”

Another advantage for cochlear implants—and all the hearing surgical procedures—is that they are covered by insurance. Insurance does not pay for hearing aids.

The implants have three parts: a headpiece, a speech processor and a receiver. The headpiece includes a microphone and a transmitter and is worn behind the ear. It picks up sound and sends it to the speech processor, which is a beeper-sized device that can be worn on a belt or carried in a pocket. The speech processor converts sound into a signal that is sent to the receiver, which is implanted subcutaneously behind the ear. The receiver sends a sound signal to the brain, which “hears” the sound.

But surgery is not without risks. The complication rate for cochlear implants in adults is roughly 5%, according to the NIH advisers, and the pediatric complication rate is less. That compares favorably to the most common device implantations-pacemakers and implantable cardioverter defibrillators, which have a 10% surgical complication rate.

Most importantly, the cochlear implant offers entry into “the hearing world,” a world that may not be suitable for all people with hearing loss, said Whitelaw. “This requires a big decision. The hearing world is not for everyone and many families chose a different path.”

Source: Archives of Pediatric and Adolescent Medicine

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