COCHLEAR IMPLANT: A MODERN MEDICAL MARVEL

by Stan Griffin, Deaf Friends International Special Contributor

Hearing loss is the most prevalent and fastest-growing disability in North America. There are many reasons. An ever-growing aging population and the increasing amount and volume of noise pollution are just two. Statistics indicate that one in ten Americans have some sort of hearing problem.

If you are one of those people, there are a number of options available to improve your way of life. You can learn American Sign Language or how to read lips. There are hearing aids that increase the volume of voices and sounds you hear. When it comes to communicating on the telephone, there is a device known as a "TDD."

The newest development is the "first effective artificial sensory organ developed for humans" and "one of the most rapid advances ever made in medical technology." It is the most important advance in the history of profound deafness treatment. The device is surgically grafted in the skull behind the ear and stimulates nerve of hearing with small wires touching the cochlea, a snail-like part of the inner ear. This modern marvel is called a "COCHLEAR IMPLANT."

It is a prosthetic replacement, a medical device designed to bypass damaged parts of the inner ear and is often called a "bionic ear." Estimates place the number of people who could benefit from this implant at 200,000-500,000. To date, over 50,000 individuals worldwide have undergone the necessary surgery. Three prominent recipients are conservative talk show host Rush Limbaugh, Heather Whitestone (Miss America 1995), and Gil McDougal.(New York Yankees star of the 1960s).

There has been a long history of attempts to improve hearing by electrical stimulation, going back hundreds of years. Successful development of the implant has progressed since that time. Many research teams have been involved, and each has built on the work of those who came before. As a result, it is not possible to single out one person and call him "sole" inventor of the cochlear implant.

The first scientist to stimulate the auditory system electrically was Count Alessandro Volta, Italian physician and chemist. (The unit of electromotive force was named for him.) In 1790 he inserted two metal rods into his ears and connected them to a battery of approximately 50 volts. When the circuit was complete, he got a sensation described as "a boom within the head," followed by a sound like that of thick, boiling soup.

Volta’s experiment sparked crude applications of electric stimulation all over Europe. For more than 150 years, scientists continued to investigate the subject, seeking ways to improve the hearing of both old and young. Men like the Duchenne of Bologna, Brenner, Weaver and Bray, Gusconi and Volokhov, Stevens and Jones studied the problem and conducted experiments. However, their work met with varying degrees of success, and results were inconclusive.

By the 1950s, tiny steps forward turned into giant strides. One of the first documented cases of successful implants, stimulation of the acoustic nerve by direct electrode application in a totally deaf person, was cited by Djourno and Eyries in 1957. They placed wires on nerves exposed during an operation and reported the first in-depth description of effects. Their patient heard sounds like "a roulette wheel" and "a cricket" when current was applied, and he was aware of background noise. Considerable doubt about the safety of inserting anything into the inner ear was eased with the development of microsurgical techniques.

The 1970s were a "decade of controversy" with a lot of publicity. Questions swirled: Who should be implanted? Which device should we use? What are the chances for success? When should we sign up for surgery? How safe is the procedure?

Men working to answer those questions by searching for a successful multi-channel cochlear implant device were: William House in Los Angeles; F. Blair Simmons and Robert White at Stanford University; Donald Eddington at the University of Utah; Michael Merzenick in San Francisco; Graeme Clark in Australia, and Adam Kissiah at Cape Kennedy, Florida.

GRAEME CLARK

If one person was to be credited as most important in the movement toward an effective cochlear device, it would likely be Graeme Clark, the Australian who successfully implanted the first "bionic ear" in 1978. Eleven years before, Clark had begun his research, inspired by his close relationship with his father who was deaf all his life. He set as his goal finding a way to improve the quality of life for hearing-impaired people.

Clark graduated with a degree in Medicine from the University of Sydney (1957). He set up a clinical practice in Melbourne as an ENT surgeon (ear, nose, throat). In 1969 he received a Ph.D in Physiology at Sydney. His advanced studies for that degree were on how electrical stimulation of hearing nerves might be used to restore hearing artificially.

The following year Clark was appointed to the Foundation Chair of Otolaryngology (the branch of medicine that combines treatment of the ear, nose, and throat). As leader, Clark conducted fundamental research with a multi-disciplinary team to develop an implantable hearing prosthesis. On his team were experts in: (1) physiology; (2) biology; (3) pathology; (4) bioengineering; (5) electronic and communicative engineering; (6) psychophysics; (7) speech processing; (8) speech science; (9) audiology; (10) speech pathology; and (11) rehabilitation of hearing impaired. Clark became Director of the Bionic Ear Institute in Melbourne soon after its founding in 1984.

Clark subsequently assisted in the industrial development of his prototype through Nucleus (a group of medical equipment manufacturers) and its later subsidiary, Cochlear Limited. Eventually Clark’s device became a multi-channel cochlear implant that is the single, most-used implant in the world: the "Nuclear Multi-Channel Cochlear Implant." Since that time, he has supervised many more research investigations aimed at the improvement of techniques used and the range of the prosthesis’ application to congenitally deaf children and infants. Clark conducted the first successful implant operation on a child in 1985. Five years later the FDA (Food and Drug Administration) gave approval for distribution in this country.

In 1983 Clark was awarded the Order of Australia for his contributions to Medicine. In 1998 he was named a fellow of the Australian Academy of Science. He was presented with the Clunies Ross National Science & Technology Award (2002) as an outstanding example to be emulated by others. Clark’s work continues today.

ADAM KISSIAH

Adam Kissiah was unique among the many scientists involved in the "hunt" because he was not trained in any medical field. Instead he developed a cochlear implant concept while working as an engineer on the Apollo and Space Shuttle Programs at Kennedy Space Center. He used the knowledge acquired while involved with such things as electric sensing systems, telemetry, and sounds and vibrations sensors.

Around 1970 Kissiah began to lose his hearing. He had three corrective surgeries; all of them failed. Fearing the loss of his career along with his hearing, Kissiah started studying the ear, applying principles learned on the job. He was trying to find other rehabilitative possibilities. He found his answer in engineering instead of medicine.

Once Kissiah had put together a model of his implant (1977), NASA helped him get a patent; but others infringed (disregarded his rights; took his ideas without permission). He might have taken legal action against them, but he chose not to do so. His model is widely used today, but he received very little money and not much credit. In a sense, he was the "forgotten man of cochlear implants."

Kissiah is now retired. Last year he belatedly began getting some recognition for his accomplishments. He received the NASA Space Act Award for his work: a check for $21,000. He was also recognized by the IEEE engineering management society for his work in helping thousands of individuals to hear.

Earlier this year, Kissiah became a member of the Space Technology Hall of Fame, an honor bestowed on him at the Space Foundation’s 15^th Anniversary Awards Dinner (April 10, 2003) in Colorado Springs. The Foundation’s goals are to honor inventors who transform space technology into commercial products, increase public awareness of space spin-off technology benefits, and encourage future innovations.

Kissiah has said: "It’s nice to know I contributed to making many lives better. That’s special. It allows me to think that perhaps I did something that helped ... It’s amazing to see people hear again."

HOW THIS "MARVEL" WORKS

The various cochlear implant designs are constantly changing, evolving, and improving. Brands are not completely uniform, so the general description which follows could very well apply to some and not to others. Some might even be outdated.

All brands of implants have the same basic parts. Three are external (located outside the body), and two are internal (surgically placed inside the body).

EXTERNAL:

1. A Microphone picks up sounds and speech and sends them to a Speech Processor (Signal Processor) through thin cables running under clothing. Often it’s worn as an earpiece, like an over-the-ear hearing aid.

2. The Speech/ Signal Processor (cigarette package-size) converts, filters and sometimes digitalizes sound into coded electronic signals that are sent on cables back to the headset’s transmitting coil. This is worn on the belt, in a pocket, or on the back in a harness under clothing. (Newer models move it to a behind-the-ear position and combine it with the microphone.)

3. The Transmitter (quarter-size) has a coil held in place by a magnet drawn to another magnet under the skin. After decoding signals from the Processor, it sends a message as FM radio signals to another coil in the Receiver-Stimulator (close to the ear under the skin).

INTERNAL:

4. The Receiver-Stimulator has a second coil that decodes the signals and transforms them into a pattern of electrical impulses. It determines how much electric current will be needed and sends the signals to the inner ear where they stimulate the appropriate electrodes.

5. An Electrode array is placed inside the cochlea in the inner ear. Their position determines frequency and pitch. (The amount of current received sets volume levels.) Neuron endings are stirred by the Stimulator’s information, and they carry signals to the brain for interpretation as meaningful sound. (Some have compared the cochlea to a piano. Different parts are responsible for different pitches. When the Electrodes are activated, they depress different "piano" "keys.")

WHO PRODUCES AND SELLS THESE "MARVELS?"

There are three major manufacturers and distributors of multi-channel cochlear implants whose products are available in the U. S. today.

1. Cochlear Corporation: They were the first to build and send out implants into the world. The parent company is in Australia, and an American headquarters is located in Englewood, Colorado. They have six subsidiaries worldwide. Their "Nucleus 22" was the first system approved by the FDA for use in this country. Updated versions are the"Nucleus 24" and the "Nucleus 24RCS." The estimated number of recepients are 36,000 in countries speaking 23 different languages.

2. Advanced Bionics Corporation: They entered the field in 1995; at that time they were the only manufacturer of multi-channel implants. They are based in California. Their appearance added competition and created an environment that enabled technology to grow fast in a short time. ABC products’ names are "Clarion" and (their latest) "C II." Approximately 10,000 men, women, and children have chosen operations implanting their models.

3. Med El Corporation: They are situated in Innsbruck, Austria with a U. S. outlet in Raleigh, North Carolina. They have been active in the field since the early 1980s with single-channel devices, marketing first in Europe and (in 1994) in the U. S. Their device "Med El" evolved from an early model ("Combi 40") to their latest "Tempo 40." Their records show that about 6,000 of their models have been purchased.

THE OPERATION

Typically, the implant operation takes 1 ½ to 5 hours, depending on the specific apparatus. A general anesthetic is used. The patient’s hospital stay is usually one day for adults and 1-2 days for children. Medical costs run from $15,000-$40,000; this includes evaluation, the surgery itself, hardware (device), and rehabilitation.

Every medical procedure carries risk. The implanting could damage the inner ear and destroy all hearing. There is a possibility of skin infection, damage to facial nerves that could cause paralysis, onset of tintinitis (noise in the head), and damage to the vestibular system (part of the acoustic nerve). Statistics indicate that the chance of such side-effects is 10 percent.

Some of the characteristics that indicate a man or woman is a prime candidate: (1) has profound hearing loss in both ears; (2) has a desire to enter the hearing world, to use spoken language; (3) hearing aids are not helping; (4) is no medical reason to avoid surgery; (5) has realistic expectations about results; (6) a functioning auditory nerve is present; (7) has good speech, language, and communication skills; (8) lived a short amount of time without hearing sound; and (9) support of family and friends.