Hearing Loss and Hearing Services at LSU Health Sciences Center
Children of hearing families usually have to learn language by ear and learn to speak. Deaf Children of Deaf Families learn language through signs and usually choose not to speak. While there is considerable controversy in the field at large, LSU scientists and clinicians have learned to respect the choices families make for their children and to offer services only when requested. Services can range from family support and vocational counseling within Deaf Culture, at one end, through hearing aids and cochlear implants (a computerized device implanted in the inner ear) for access or return to the hearing world.
Some years ago it was common to divide hearing loss into two types, conductive deafness and nerve deafness, with the former being medically treated and the latter managed with hearing aids (but presumably only marginally). Now, through scientific research and study, we have learned that there are at least 70 types of inner ear deafness that can occur, and few of them involve only the nerve fibers. The problems can involve the tiny hair cells (both inner and outer) inside the hearing organ (the cochlea and organ of Corti), in which case unique types of hearing aids that simply amplify faint sounds and not loud ones are available. These are not your father's hearing aids but rather highly sophisticated devices that, if properly programmed, can compensate for the loss of outer hair cells and bring almost normal hearing to the patient in all but the most difficult listening conditions. These aids can also be fit with directional microphones to cut through intrusive noise and allow the listener to focus on a conversation in a very noisy environment. In special cases a device called an Assistive Listening Device may bring the mouth of the speaker directly to the ear of the listener over long distances.
Hearing loss caused by middle or outer ear obstructions have been commonly treated by otolaryngologists (Ear, Nose, and Throat physicians and surgeons) with medicine and/or surgery. But now we also know of many medical and surgical treatments for inner ear problems as well, and the scope of practice of otolaryngology has expanded considerably. At present, the otolaryngologist is the medical specialist most trained to handle ear disease, and audiologists with Master or Doctorate degrees are the professionals who manage hearing loss non-medically with hearing aids and advanced assessment and fitting tools. These highly skilled professionals work together to serve their populations at the peak level of efficiency.
Our laboratory scientists under Dr. Richard Bobbin have helped discover some of the chemical compounds that activate the ear, as well as some of those that shut it down. They have isolated and studied outer hair cells and the structural support cells that keep the ear working.
In 1990, the lab began a long and fruitful collaboration with Dr. Bronya Keats and her colleagues in the Department of Genetics. The collaboration was based initially on NIH funding for the lab which in part supported Kresge scientists, as well as Dr. Keats and some of her colleagues. As the decade neared its end, Dr. Keats received a large award from the Federal government to serve the genetics needs of the Acadian community. This Federal support dovetailed with other funding that allowed both research and service programs to work hand-in-hand. In supporting service to Acadian communities, Dr. Keats made available auditory screening programs with otoacoustic emissions and other tests as part of screening patients for visual and retinal deficits as well, while studying and serving patients with Usher syndrome as well as those with Friedreich ataxia. These two genetic diseases are found in Louisiana populations, and Dr. Keats and her colleagues have been successful in locating the mutations that cause them.
The auditory system has yielded some of its most exciting secrets to genetic and molecular study in the past few years, and the LSU team, led by Dr. Keats, has been in the forefront not only of the discoveries but their rapid application to clinical practice. For example, in collaboration with NIH scientists and other colleagues around the world, we have participated in a study that identified a specific mutation of a Gap Junction Protein which leads to severe deafness. The place of the mutation on the gene differs with people of various ethnic extractions. Dr. Hood, in a series of NIH-supported studies, is complementing these findings by working on techniques to identify carriers by objective audiological tests alone.
We have also learned that objective and early identification of deafness leads to excellent management and language learning, whether families want their child to be raised in the hearing, Deaf, or both worlds. Knowledge is power, and suitable educational management and language learning follow correct diagnosis. LSU scientists have developed techniques for objectively differentiating types of deafness that would respond well to hearing aids versus types that would not respond to hearing aids or auditory verbal therapy (a problem called Auditory Neuropathy or Auditory Dys-synchrony). The management of such children requires the use of sign language and/or Cued Speech rather than depriving the child of visual input and asking the child to learn to learn by ear alone. However, cochlear implants have been shown to be remarkably successful in bringing such children into the hearing world if their families were so inclined.
The laboratory and some of its surgeons have helped LSU, in collaboration with the Eye and Ear Hospital, lead the way in the use of Cochlear Implants as a means for deaf people to learn language by ear. (For more information see www.kresgelab.org). With regard to cochlear implants, an area where Louisiana has been in the forefront since the mid-1980s, Dr. Charles Parkins, our most experienced surgeon, and his colleagues have contributed to the better understanding of electrical field dispersion and how cochlear implants stimulate residual nerve fibers inside the ear.
LSU's cochlear Implant Program, under the direction of Dr. Linda Hood, has implanted more than 150 people; a collaborative program with the Eye and Ear Hospital, Tammy Crabtree and the Joachim Hearing and Speech Center, it focuses properly on the use of Auditory Verbal Therapy and speech use among the deaf after the implant is in place. Among the things we have learned is that the use of visual languages must be curtailed as much as possible after implants are activated, and that we must ask for flexibility as well as accommodation from the educators throughout our state who serve our patients after they have been implanted.
In summary, we are entering a new age of identification, understanding, and care for hearing loss in our State. We have one of the country's finest resources as part of LSU Health Sciences Center, and we are here to serve you.
If you have a hearing impaired child visit www.listen-up.org as an important unbiased resource and contact with other parents.
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