Cochlear implant

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

File:Cochlear implant.jpg

Illustration of the internal parts of a cochlear implant.

Overview

A cochlear implant (CI) is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. The cochlear implant is often referred to as a bionic ear. Unlike hearing aids, the cochlear implant does not amplify sound, but works by directly stimulating any functioning auditory nerves inside the cochlea with electrical impulses. External components of the cochlear implant include a microphone, speech processor and transmitter which also provides an individual to adjust the sound for quality and amplification.

According to researchers at the University of Michigan [2], approximately 100,000 people worldwide have received cochlear implants; roughly half are children and half are adults. The vast majority are in developed countries due to the high cost of the device, surgery and post-implantation therapy — Mexico had performed only 55 cochlear implant operations by the year 2000 (Berruecos 2000). China will be having 15,000 cochlear implant surgeries on children, which are being paid for by a Taiwanese philanthropist. The concern is that the follow-up services in China are not adequate to meet the needs of cochlear implanted children. A small percentage of those now have bilateral implants, or one on each cochlea. Bilateral cochlear implants are a growing trend globally, Cochlear Americas reported that 15% of their 2006 sales in the United States were for bilateral implants. [3]

Individuals who have acquired deafblindness (loss of hearing and vision combined) may find cochlear implants a radical improvement in their daily life. It may provide them with more information for safety, communication, balance, orientation and mobility and promote interaction within their environment and with other people, reducing isolation. Having more auditory information that they may be familiar with may provide them independent gathering of information to become more independent.

The implant often gives recipients additional auditory information, which may include sound discrimination fine enough to understand speech in quiet environments. Though sufficient, and quality, post-implantation rehabilitative therapy is a critical factor affecting the success rate.

The introduction of cochlear implants has seen the renewal of a century-old debate about models of deafness that often pits the hearing parents of deaf children on one side and the Deaf community on the other. There still exists much debate regarding the value and necessity of an implant, some of which is detailed in the below ethical, cultural, and social impact sections.

History

The discovery that electrical stimulation to the auditory system can create a perception of sound occurred around 1790, when Alessandro Volta (the developer of the electric battery) placed metal rods in his own ears and connected them to a 50-volt circuit, experiencing a jolt and hearing a noise "like a thick boiling soup". Other experiments occurred sporadically, until electrical (sound amplifying) hearing aids began to be developed in earnest in the 20th century.

The first direct stimulation of an acoustic nerve with an electrode was performed in the 1950s by the French-Algerian surgeons André Djourno and Charles Eyriès. They placed wires on nerves exposed during an operation, and reported that the patient heard sounds like "a roulette wheel" and "a cricket" when a current was applied.

In 1961, American doctor William F. House of House Ear Institute [4] and House Ear Clinic[5] had Djourno's paper translated and had devices made which he implanted into three patients. In 1969 he created the first wearable implant. House's technology used a single electrode and was designed to aid lip-reading. Throughout the 1970s, University Of Melbourne researcher Graeme Clark, initially inspired to develop an artificial hearing device through his deaf father[6], developed implants which stimulated the cochlea at multiple points, and on the 1st of August, 1978, Melbourne resident Rod Saunders was implanted with the first Australian multi-channel cochlear implant. Although other multi-channel implants had been performed since 1964, this marked the beginning of one of the most successful.

In December 1984, the Australian cochlear implant was approved by the United States Food and Drug Administration to be implanted into adults in the United States. In 1990 the FDA lowered the approved age for implantation to 2 years, then 18 months in 1998, and finally 12 months in 2002, although off label use has occurred in babies as young as 6 months in the United States and 4 months internationally.

Throughout the 1990s, the large external components which had been worn strapped to the body grew smaller and smaller thanks to developments in miniature electronics. By 2006, most school-age children and adults used a small behind-the-ear (BTE) speech processor about the size of a power hearing aid. Younger children have small ears and might mishandle behind-the-ear speech processors, therefore, they often wear the sound processor on their hip in a pack or small harness, or wear the BTE's pinned to their collar, barrette or elsewhere.

On October 5, 2005, the first of 3 recipients was implanted with a totally implantable cochlear implant (TIKI sic) in Melbourne, Australia. This was part of a research project conducted by Cochlear Ltd. and the University of Melbourne Department of Otolaryngology under the umbrella of CRC HEAR to be the first cochlear implant system capable of functioning for sustained periods with no external components. The system is capable of providing hearing via TIKI in standalone mode (invisible hearing), or via an external sound processor. Although these recipients continue to use their devices successfully today, it will be many years before a commercial product becomes available.

Since hearing in two ears allows people to localize sounds and to hear better in noisy environments, bilateral (both ear) implants are currently being investigated and utilized. Users generally report better hearing with two implants, and tests show that bilateral implant users are better at localizing sounds and hearing in noise. Nearly 3000 people worldwide are bilateral cochlear implant users, including 1600 children. As of 2006, the world's youngest recipient of a bilateral implant was just over 5 months old (163 days) in Germany (2004).

Parts of the cochlear implant

The implant is surgically placed under the skin behind the ear. The basic parts of the device include:

External:

• a microphone which picks up sound from the environment
• a speech processor which selectively filters sound to prioritise audible speech and sends the electrical sound signals through a thin cable to the transmitter,
• a transmitter, which is a coil held in position by a magnet placed behind the external ear, and transmits the processed sound signals to the internal device by electromagnetic induction,

Internal:

• a receiver and stimulator secured in bone beneath the skin, which converts the signals into electric impulses and sends them through an internal cable to electrodes,
• an array of up to 22 electrodes wound through the cochlea, which send the impulses to the nerves in the scala tympani and then directly to the brain through the auditory nerve system.

Candidates

There are a number of factors that determine the degree of success to expect from the operation and the device itself. Cochlear implant centers determine implant candidacy on an individual basis and take into account a person's hearing history, cause of hearing loss, amount of residual hearing, speech recognition ability, health status, and family commitment to aural habilitation/rehabilitation.

A prime candidate is described as:

• having severe to profound sensorineural hearing impairment in both ears
• having a functioning auditory nerve
• having lived a short amount of time without hearing (approximately 70+ decibel loss, on average)
• having good speech, language, and communication skills, or in the case of infants and young children, having a family willing to work toward speech and language skills with therapy
• not benefitting enough from other kinds of hearing aids
• having no medical reason to avoid surgery
• living in or desiring to live in the "hearing world"
• having realistic expectations about results
• having the support of family and friends
• having appropriate services set up for post-cochlear implant aural rehabilitation (through a speech language pathologist, deaf educator, or auditory verbal therapist).

Type of hearing impairment

People with mild or moderate sensorineural hearing loss are generally not candidates for cochlear implantation. After the implant is put into place, sound no longer travels via the ear canal and middle ear but will be picked up by a microphone and sent through the device's speech processor to the implant's electrodes inside the cochlea. Thus, most candidates have been diagnosed with profound sensorineural hearing loss.

The presence of auditory nerve fibres is essential to the functioning of the device: if these are damaged to such an extent that they cannot receive electrical stimuli, the implant will not work. A small number of individuals with severe auditory neuropathy may also benefit from cochlear implants.

Age of recipient

Post-lingually deaf adults and pre-lingually deaf children form two distinct groups of potential users of cochlear implants with different needs and outcomes. Those who have lost their hearing as adults were the first group to find cochlear implants useful, in regaining some comprehension of speech and other sounds. If an individual has been deaf for a long period of time, the brain may begin using the area of the brain normally used for hearing for other functions. If such a person receives a cochlear implant, the sounds can be very disorienting, and the brain often will struggle to readapt to sound.

The risk of surgery in the older patient must be weighed against the improvement in quality of life. As the devices improve, particularly the sound processor hardware and software, the benefit is often judged to be worth the surgical risk, particularly for the newly deaf elderly patient. [7]

The other group of customers are parents of children born deaf who want to ensure that their children grow up with good spoken language skills. Research shows that congenitally deaf children who receive cochlear implants at a young age (less than 2 years) have better success with them than congenitally deaf children who first receive the implants at a later age, though the critical period for utilizing auditory information does not close completely until adolescence.

Number of users

It has been estimated in 2002 that around 10,000 children in the US and an additional 49,000 people worldwide have received Cochlear implants. By the end of 2007, the total number of cochlear implant recipients has grown to an estimated 120,000 worldwide.

The operation, post-implantation therapy and ongoing effects

File:Cochlear implant2.jpg

Cochlear implant as worn by user

The device is surgically implanted under a general anaesthetic, and the operation usually takes from 1½ to 5 hours. First a small area of the scalp directly behind the ear is shaved and cleaned. Then a small incision is made in the skin just behind the ear and the surgeon drills into the mastoid bone and the inner ear where the electrode array is inserted into the cochlea. The patient normally goes home the same day as the surgery, although some cochlear implant recipients stay in the hospital for 1 to 2 days. It is considered outpatient surgery. As with every medical procedure, the surgery involves a certain amount of risk; in this case, the risks include skin infection, onset of tinnitus, damage to the vestibular system, and damage to facial nerves that can cause muscle weakness, or, in worst cases, disfiguring paralysis. There is also the risk of device failure, usually where the incision does not heal properly. This occurs in 2% of cases and the device must be removed. The operation also may destroy any residual hearing the patient may have; as a result, some doctors advise single-ear implantation, saving the other ear in case a biological treatment becomes available in future.

After 1-4 weeks of healing (the wait is usually longer for children than adults), the implant is turned on or activated. Results are typically not immediate, and post-implantation therapy is required as well as time for the brain to adapt to hearing new sounds. In the case of congenitally deaf children, audiological training and speech therapy typically continue for years, though infants can become age appropriate in a matter of months. The participation of the child's family in working on spoken language development is considered to be even more important than therapy. The family can aid development by participating actively in the child's therapy, making hearing and listening interesting, talking about objects and actions, and encouraging the child to make sounds and form words.

In 2003, the CDC and FDA announced that children with cochlear implants are at a slightly increased risk of bacterial meningitis (Reefhuis 2003). Though this risk is small, it is still 30 times higher than children in the general population, without proper immunizations. Many users, audiologists, and surgeons also report that when there is an ear infection causing fluid in the middle ear, it can affect the cochlear implant, leading to temporarily reduced hearing.

The implant has a few effects unrelated to hearing. Manufacturers have cautioned against scuba diving due to the pressures involved, but the depths found in normal recreational diving appear to be safe. The external components must be turned off and removed prior to swimming or showering. Some brands of cochlear implant are unsafe in areas with strong magnetic fields, and thus cannot be used with certain diagnostic tests such as magnetic resonance imaging (MRI), but some are now FDA approved for use with certain strengths of MRI machine. Large amounts of static electricity can cause the device's memory to reset. For this reason, children with cochlear implants are also advised to avoid plastic playground slides. [8] The electronic stimulation the implant creates appears to have a positive effect on the nerve tissue that surrounds it.

Cost

In the United States, medical costs run from USD$45,000 to $105,000; this includes evaluation, the surgery itself, hardware (device), hospitalization and rehabilitation. Some or all of this may be covered by health insurance. In the United Kingdom, the NHS covers cochlear implants in full, as does Medicare in Australia.

Efficiency

A cochlear implant will not cure deafness or hearing impairment, but is a prosthetic substitute for hearing. Some recipients find them very effective, others somewhat effective and some feel overall worse off with the implant than without. [9] For people already functional in spoken language who lose their hearing, cochlear implants can be a great help in restoring functional comprehension of speech, especially if they have only lost their hearing for a short time.

British Member of Parliament Jack Ashley received a cochlear implant in 1994 at age 70 after 25 years of deafness, and reported that he has no trouble speaking to people he knows one on one, even on the telephone, although he might have difficulty with a new voice or with a busy conversation, and still had to rely to some extent on lipreading. He described the robotic sound of human voices perceived through the cochlear implant as "a croaking dalek with laryngitis". Even modern cochlear implants have at most 24 electrodes to replace the 16,000 delicate hair cells that are used for normal hearing. However, the sound quality delivered by a cochlear implant is often good enough that many users do not have to rely on lipreading. Rush Limbaugh, U.S. talk radio show host, says that everything sounds normal except that he cannot pick out the melody of new music that he had not heard prior to becoming deaf.

Adults who have grown up deaf can find the implants ineffective or irritating. This relates to the specific pathology of deafness and the time frame. Adults who are born with normal hearing and who have had normal hearing for their early years and who have then progressively lost their hearing tend to have better outcomes than adults who were born deaf. This is due to the neural patterns laid down in the early years of life - which are crucially important to speech perception. Cochlear implants cannot overcome such a problem. Some who were orally educated and used amplifying hearing aids have been more successful with cochlear implants, as the perception of sound was maintained through use of the hearing aid.

Many individuals who use sign language believe they have no use for sound, with the obvious exception of the detection of emergency situations (onrushing vehicles, law enforcement officials calling to them or attackers) located outside the range of vision. Individuals who are Deaf use sign language and an interpreter to communicate with those who use spoken languages, in the same way that an individual who only speaks English but wants to meet with an individual who only speaks French, would utilize an interpreter.

For small children, amazing results have been achieved with the use of cochlear implants. Almost all children hear quite well with a cochlear implant, save for a rare few. Those children without a working auditory nerve may be helped with a cochlear implant, although the results they experience may not be as spectacular. Patients without a viable auditory nerve are usually identified during the candidacy process. Fewer than 1% of deaf individuals have a missing or damaged auditory nerve, which today can be treated with an auditory brainstem implant. Recent research has suggested that children and adults can benefit from bilateral cochlear implants in order to aid in sound localization and speech understanding. (See Offeciers et al. 2005)

Risks and disadvantages

Some effects of implantation are irreversible; while the device promises to provide new sound information for a recipient, the implantation process inevitably results in damage to nerve cells within the cochlea, which often results in a permanent loss of most residual natural hearing. While recent improvements in implant technology, and implantation techniques, promise to minimize such damage, the risk and extent of damage still varies.

In addition, while the device can help the recipient better hear and understand sounds in their environment, it is simply incapable of replicating the quality of sound processed by a natural cochlea. As a result, some recipients can only distinguish the difference between simple sounds, such as a ringing phone vs a doorbell, while others can clearly understand speech in quiet environments, while some even gain the ability to distinguish the nuances of fine classical music. The success rate depends on a variety of factors, including technology used, condition of the recipient's cochlea, and the follow-through of post-implantation aural rehabilitation.

The FDA reports that cochlear implant recipients may be at higher risk for meningitis.[10] A study of 4,265 American children who received implants between 1997 and 2002 concluded that recipient children had a risk of pneumococcal meningitis more than 30 times greater than that for children in the general population.[11] A later, UK-based, study found that while the incidence of meningitis in implanted adults was significantly higher than the general population, the incidence in children was no different than the general population.[12]

There are strict protocols in choosing candidates to avoid risks and disadvantages. A battery of tests are performed to make the decision of candidacy easier. For example, some patients suffer from deafness medial to the cochlea - typically acoustic neuromas. Implantation into the cochlea has a low success rate with these people as the artificial signal does not have a healthy nerve to travel along.

With careful selection of candidates, the risks of implantation are minimized.

Cultural and Social Impacts

The introduction of cochlear implants has seen the renewal of a century-old debate about models of deafness that often pits the hearing parents of deaf children on one side and the Deaf community on the other. Many people who are Deaf feel they have no use for sound. Sound quality of implants and hearing aids have the ability to annoy people and just create a lot of negative noise and headaches and create safety issues. Many children throw their hearing aids away, they may feel the same way about implants. Many in the Deaf community stress that it is important for adults to choose for themself and not to force children to have implants until they are old enough to understand and choose for themself. Many hearing parents of deaf children do not feel comfortable learning sign language. More often than not, deaf or hard of hearing children of hearing parents have little or no methods to communicate and are delayed learners. Deaf children of Deaf parents show that they have closer to a normal childhood because they have a language to receive information and to express themself. University of Pittsburgh science affiliation, led by prominent bio-molecular audiologist Michael Kraemer, has crafted the basic audiological structure for the cohesion to operate properly. On the one hand, modern medical ethics law dictates that the decision of whether to get a cochlear implant is up to the patient or the legal guardian of the patient. Therefore, political debate about whether deafness is a disability or not is irrelevant to the current medical profession. On the other hand, whether society treats deafness as a disability has direct bearing on government policy. Many governments in the world have disability legislation which includes people who are deaf. Some developed countries provide cochlear implantation as a part of state healthcare.[13] The debate is also economic. Many state-funded medical interventions for a disability (such as free genetic screening for Down Syndrome) are justified on the ground that, in the long run, they will prove cheaper for the state. Some may also regard this as just another form of abuse toward individual who is deaf. Many people who are Deaf say that it is wrong to implant a child and that it is the individual's choice as an adult. Many adults are very happy with implants and it has improved their life. There is not always funding to assist individuals and families to pay for the costs of what is needed to assist individuals to understand concepts of sound if it is their first experience.

Ethical issues

Discussions within the Deaf community continue to fuel controversy and emotional personal debates about health, rights of the individual citizen, language, ethics, Deaf culture, and the death of Deaf culture. Part of the controversy concerns also the basic right for an individual to choose a language versus an individual as a young child having a mode of communication and language chosen for them. In the past, many adults whose first language is sign language endured policies created by medical and educational governing bodies that enforced the use of spoken language and use of hearing aids on them. One argument made by those in the Deaf community opposed to cochlear implants is that implantation of CI's in young children is just another form of abuse. In the past, individuals who were Deaf have advocated change successfully to improve human rights for individuals and continue to work to advocate for change, to help children who are born with loss of hearing.

Cochlear implants for congenitally deaf children are often considered to be most effective when implanted at a young age, during the critical period in which the brain is still learning to interpret sound; hence they are implanted before the recipients can decide for themselves. Critics question the ethics of such invasive elective surgery on otherwise healthy children. They point out that manufacturers and specialists have exaggerated the efficacy and downplayed the risks of a procedure that they stand to gain from. On the other hand, Andrew Solomon of the New York Times states that "Much National Association of the Deaf propaganda about the danger of implants is alarmist; some of it is positively inaccurate."

Much of the strongest objection to cochlear implants has come from the Deaf community, which consists largely of pre-lingually deaf people whose first language is a signed language. Regardless of the fact that to be deaf is to lack the ability to hear, many individuals who are Deaf and the Deaf community do not share the view of deafness held by the hearing parents of deaf children, which obviously regards deafness as a disability to be "fixed." Individuals who are Deaf celebrate their diverse culture (see Deaf culture). On the other hand, many people feel that refusing to implant deaf children is unethical, comparable to refusal to treat any other handicap or disease that can be effectively alleviated. Many individuals who can hear, or who have become deaf due to injury or illness, are not comfortable with the thought of a child that lacks the sense most commonly associated with human language. Individuals who are Deaf may feel that implants are just another form of mental and physical abuse in the long history of punishments, abuse and pain they have had to endure.

The conflict over these opposing models of deafness has raged since the 18th century, and cochlear implants are the latest in a history of medical interventions promising to turn a deaf child into a hearing child — or, more accurately, into a child with a mild or moderate hearing impairment.

Critics argue that the cochlear implant and the subsequent therapy often become the focus of the child's identity, at the expense of a Deaf identity and ease of communication in sign language. Measuring the child's success by their success in hearing and speech will lead to a poor self-image as "disabled" (because the implants do not produce normal hearing) rather than having the healthy self-concept of a proud Deaf person.

Some writers have noted that children with cochlear implants are more likely to be educated orally and without access to sign language (Spencer et al 2003). Children with implants are also often isolated from other deaf children and from sign language (Spencer 2003), and instead are 'married' to a team of hearing experts who will monitor his cochlear implant and adjust the speech processor, at great expense. Children do not always receive support in the educational system to support their needs as they may require special education environments and EA's Educational Assistants. According to Johnston (Johnston 2004), cochlear implants have been one of the technological and social factors implicated in the decline of sign languages in the developed world. Some of the more extreme responses from Deaf activists have labelled the widespread implantation of children as "cultural genocide". As cochlear implants began to be implanted into deaf children in the mid to late 1980s, the Deaf community responded with protests in the US, UK, Germany, Finland, France and Australia.

Opposition continues today but is softening. As the trend for cochlear implants in children grows, Deaf-community advocates have tried to counter the "either or" formulation of oralism vs manualism with a "both and" approach; some schools now are successfully integrating cochlear implants with sign language in their educational programs. However, some opponents of sign language education argue that the most successfully implanted children are those who are encouraged to listen and speak rather than overemphasize their visual sense. Significantly, deaf individuals have a high rate of illiteracy due to the phonetic nature of the western writing systems; it is thought that cultivating the auditory senses will help a hearing impaired child to avoid this problem. However, others (mainly Deaf people who have been through education in decades past) feel that the high levels of relative illiteracy is mainly due to profoundly deaf children being taught orally, despite being sign language users and not being able to fully understand speech. Oral education in the past, though, was vastly different from the approaches today, which have the benefit of hearing with cochlear implants. Previous generations relied heavily on lipreading; a fairly high percent of today's implanted person can often can hear well or only have moderate hearing loss, and depending on the individual, no lipreading whatsoever.

A recent study about attitudes of young, implanted people shows, that their feelings about the implantation are overhelmingly positive; although they are aware of the negative effects, too. None of the teenagers participating in the study criticised their parents for making the decision. They developed a positive identity, felt that they belonged to both the hearing and Deaf worlds; although only some of them use both spoken and sign language.

Functionality

The implant works by using the tonotopic organization of the basilar membrane of the inner ear. "Tonotopic organization", also referred to as a "frequency-to-place" mapping, is the way the ear sorts out different frequencies so that our brain can process that information. In a normal ear, sound vibrations in the air lead to resonant vibrations of the basilar membrane inside the cochlea. High-frequency sounds (i.e. high pitched sounds) do not pass very far along the membrane, but low frequency sounds pass farther in. The movement of hair cells, located all along the basilar membrane, creates an electrical disturbance that can be picked up by the surrounding nerve cells. The brain is able to interpret the nerve activity to determine which area of the basilar membrane is resonating, and therefore what sound frequency is being heard.

In individuals with sensorineural hearing loss, hair cells are often fewer in number and damaged. Hair cell loss or absence may be caused by a genetic mutation or an illness such as meningitis. Hair cells may also be destroyed chemically by an ototoxic medication, or simply damaged over time by excessively loud noises. The cochlear implant bypasses the hair cells and stimulates the cochlear nerves directly using electrical impulses. This allows the brain to interpret the frequency of sound as it would if the hair cells of the basilar membrane were functioning properly (see above).

Processing

Sound received by the microphone must next be processed to determine how the electrodes should be activated.

Filterbank strategies use Fast Fourier Transforms to divide the signal into different frequency bands. The algorithm chooses a number of the strongest outputs from the filters, the exact number depending on the number of implanted electrodes and other factors. These strategies emphasize transmission of the spectral aspects of speech. Although coarse temporal information is presented, the fine timing aspects are as yet poorly perceived and this is the focus of much current research.

Feature extraction strategies used features which are common to all vowels. Each vowel has a fundamental frequency (the lowest frequency peak) and formants (peaks with higher frequencies). The pattern of the fundamental and formant frequencies is specific for different vowel sounds. These algorithms try to recognize the vowel and then emphasize its features. These strategies emphasize the transmission of spectral aspects of speech. Feature extraction strategies are no longer widely used.

Transmitter

This is used to transmit the processed sound information over a radio frequency link to the internal portion of the device. Radio frequency is used so that no physical connection is needed, which reduces the chance of infection. The transmitter attaches to the receiver using a magnet that holds through the skin.

Receiver

This component receives directions from the speech processor by way of magnetic induction sent from the transmitter. (The receiver also receives its power through the transmission.) The receiver is also a sophisticated computer that translates the processed sound information and controls the electrical current sent to the electrodes in the cochlea. It is embedded in the skull behind the ear.

Electrode array

The electrode array is made from a type of silicone rubber, while the electrodes are platinum or a similarly highly conductive material. It is connected to the internal receiver on one end and inserted into the cochlea deeper in the skull. (The cochlea winds its way around the auditory nerve, which is tonotopically organized just as the basilar membrane is). When an electrical current is routed to an intracochlear electrode, an electrical field is generated and auditory nerve fibers are stimulated.

In the devices manufactured by Cochlear Ltd, two electrodes sit outside the cochlea and acting as grounds-- one is a ball electrode that sits beneath the skin, while the other is a plate on the device. This equates to 24 electrodes in the Cochlear-brand 'nucleus' device, 22 array electrodes within the cochlea and 2 extra-cochlear electrodes.

Speech Processors

Speech Processors are the component of the cochlear implant that transforms the sounds picked up by the microphone into electronic signals capable of being transmitted to the internal receiver. The coding strategies programmed by the user's audiologist are stored in the processor, where it codes the sound accordingly. The signal produced by the speech processor is sent through the coil to the internal receiver, where it is picked up by radio signal and sent along the electrode array in the cochlea.

There are primarily two forms of speech processors available. The most common kind is called the "behind-the-ear" processor, or BTE. It is a small processor that is kept worn on the ear, typically together with the microphone. This is the kind of processor used by most adults and older children.

The other form is called a body-worn-processor. This is the kind used typically by younger children, whose ears are too small to properly fit the bulky BTE processor (though it is gradually being phased out, with baby and child friendly BTEs on the market). The body worn processor is kept on the user's body, and a long wire extends up to the microphone earpiece to connect it with the processor. Users of the body worn processor have to find some creative way where to place the body worn processor. Some mothers place the processor on the child's back in a pocket sewn onto a T-shirt or onesie, others use a harness that clips across the child's chest. In July 2007, Cochlear Corp., the maker of the Nucleus brand of cochlear implants, announced that they will be making an accessory called "Babyworn", that will allows the BTE processor to be worn with a small battery pack that will clip onto the babies clothing. This will possibly diminish demand for the Bodyworn style processor. Advanced Bionics will likely come out with a similar accessory for their processor in the near future. Med-el has had a baby-friendly BTE which pins on the collar on the U.S. market since the fall of 2001; 70% of their market is to children.

Programming the speech processor

The cochlear implant must be programmed individually for each user. The programming is performed by an audiologist trained to work with cochlear implants. The audiologist sets the minimum and maximum current level outputs for each electrode in the array based on the user's reports of loudness. The audiologist also selects the appropriate speech processing strategy and program parameters for the user.

Manufacturers

Currently (as of 2007), the three cochlear implant devices approved for use in the U.S. are manufactured by Cochlear Limited, Australia, MED-EL, Austria and Advanced Bionics, US. In the EU, an additional device manufactured by Neurelec, of France is available. Each manufacturer has adapted some of the successful innovations of the other companies to their own devices. There is no clear-cut consensus that any one of these implants is superior to the others. Users of all four devices display a wide range of performance after implantation.

Since the devices have a similar range of outcomes, other criteria are often considered when choosing a cochlear implant: usability of external components, cosmetic factors, battery life, reliability of the internal and external components, MRI compatibility, mapping strategies, customer service from the manufacturer, the familiarity of the user's surgeon and audiologist with the particular device, and anatomical concerns.

Cochlear America's Australian Stock Exchange filings in August 2007 reported a record profit of A$100 million (or just over US$85 million) and a 70% market share.

Cochlear's 2007 annual report acknowledges that a Federal investigation continues into its payments to physicians and providers. In February 2007, part of the whistleblower complaint against Cochlear filed by former Chief Financial Officer Brenda March was unsealed by the U.S. District Court for the District of Colorado. The complaint alleges that Cochlear violated the Federal anti-kickback statute through its Partners Program, which offered credits towards free or discounted products for physicians who implanted Cochlear devices, as well as gifts, trips, and other gratuities paid to physicians and providers. The government intervened in the case and transferred it from the U.S. Department of Justice to the Health and Human Services Inspector General for the imposition of civil penalties. The amount of sanctions are not yet known.

Cochlear implant in popular culture

In 2000, an Academy Award nominated documentary film Sound and Fury depicted the cultural divide between the Deaf community and children with cochlear implants. The Artinian family themselves are a "microcosm" of the Deaf culture war and two children – Peter (11 months old) and Heather (7 yrs old) – are caught in the middle. Many of the family members who opposed cochlear implants later went on to receive implants or allow their children to be implanted, and have become strong advocates for cochlear implants.

Famous recipients of cochlear implants include British MP Jack Ashley, conservative U.S. talk-show host Rush Limbaugh, British designer and typographer Tony Malone, and Heather Whitestone, Miss America 1995. Sigrid Cerf, wife of the creator of TCP/IP and Chief Internet Evangelist Vint Cerf, has two cochlear implants. Vint Cerf has a hearing impairment himself, and has spoken in support of the Hear and Say Centre, a cochlear implant and speech training organisation based in Brisbane, Australia.

On the television show ER, Reese Benton, the son of Dr. Peter Benton, is born deaf and his father briefly considers giving his son a cochlear implant.

On the television show Scrubs, the son of Mr. Francis is a child born deaf that ends up receiving a cochlear implant.

On the long running soap opera The Young and The Restless, Neil and Drusilla Winters adoptive son Devon lost his hearing due to meningitis and got a Cochlear Implant so he could hear again.

On the long running soap opera "Guiding Light", actress Amy Ecklund received a cochlear implant in 1999. It was later written into the show.

A Cochlear Implant is present in the video game series Splinter Cell as a means of communication without obvious microphones and the risk of being overheard and is used by the protagonist Sam Fisher.

On the television show, "What About Brian", the daughter of Dave and Deena, Carrie, gets a cochlear implant. The factual inaccuracies brought much criticism from people and families who have experienced cochlear implants.

The Michael Moore film Sicko documents one family's fight against CIGNA to receive a sequential bilateral cochlear implant for their daughter. Their child was a client of the Let Them Hear Foundation Insurance Advocacy Program. After several other appeals and an investigation opened by the Florida Attorney General, CIGNA finally changed their policy to include bilateral cochlear implants as a standard benefit in all traditionally insured plans in May 2007.

On the television show, "CSI: Miami", one of the co-conspirators in a prison escape has a cochlear implant which is found by the Medical Examiner when her scalpel is magnetically attracted to the implant.

See also

• Brain implant
• Neuroprosthetics
• Noise health effects
• Hearing Aid

References

• Berruecos, Pedro. (2000). Cochlear implants: An international perspective - Latin American countries and Spain. Audiology. Hamilton: Jul/Aug 2000. Vol. 39, 4:221-225
• Chorost, Michael. (2005). Rebuilt: How Becoming Part Computer Made Me More Human. Boston: Houghton Mifflin.
• Christiansen, John B., and Irene W. Leigh (2002,2005). Cochlear Implants in Children: Ethics and Choices. Washington, DC: Gallaudet University Press.
• Djourno A, Eyriès C. (1957). 'Prothèse auditive par excitation électrique à distance du nerf sensoriel à l'aide d'un bobinage inclus à demeure.' In: La Presse Médicale 65 no.63. 1957.
• Djourno A, Eyriès C, (1957) 'Vallencien B. De l'excitation électrique du nerf cochléaire chez l'homme, par induction à distance, à l'aide d'un micro-bobinage inclus à demeure.' CR de la société.de biologie. 423-4. March 9, 1957.
• Eisen MD (2003), 'Djourno, Eyries, and the first implanted electrical neural stimulator to restore hearing.' in: Otology and Neurotology. 2003 May;24(3):500-6.
• Grodin, M. (1997). Ethical Issues in Cochlear Implant Surgery: An Exploration into Disease, Disability, and the Best Interests of the Child. Kennedy Institute of Ethics Journal 7:231-251.
• Johnston, Trevor. (2004). W(h)ither the Deaf Community? In 'American Annals of the Deaf' (volume 148 no. 5),
• Lane, H. and Bahan, B. (1998). Effects of Cochlear Implantation in Young Children: A Review and a Reply from a DEAF-WORLD Perspective. Otolaryngology: Head and Neck Surgery 119:297-308.
• Lane, Harlan (1993), Cochlear Implants:Their Cultural and Historical Meaning. In 'Deaf History Unveiled', ed. J.Van Cleve, 272-291. Washington, D.C. Gallaudet University Press.
• Lane, Harlan (1994), The Cochlear Implant Controversy. World Federation of the Deaf News 2 (3):22-28.
• Litovsky, Ruth Y., et al. (2006). "Bilateral Cochlear Implants in Children: Localization Acuity Measured with Minimum Audible Angle." Ear & Hearing, 2006; 27; 43-59.
• Miyamoto, R.T.,K.I.Kirk, S.L.Todd, A.M.Robbins, and M.J.Osberger. (1995). Speech Perception Skills of Children with Multichannel Cochlear Implants or Hearing Aids. Annals of Otology, Rhinology and Laryngology 105 (Suppl.):334-337
• Officiers, P.E., et. a. (2005). "International Consensus on bilateral cochlear implants and bimodal stimulation." Acta Oto-Laryngologica, 2005; 125; 918-919.
• Osberger M.J. and Kessler, D. (1995). Issues in Protocol Design for Cochlear Implant Trials in Children: The Clarion Pediatric Study. Annals of Otology, Rhinology and Laryngology 9 (Suppl.):337-339.
• Reefhuis J, et al. (2003) Risk of Bacterial Meningitis in Children with Cochlear Implants, USA 1997-2002. New England Journal of Medicine, 2003; 349:435-445.
• Spencer, Patricia Elizabeth and Marc Marschark. (2003). Cochlear Implants: Issues and Implications. In 'Oxford Handbook of Deaf Studies, Language and Education', ed. Marc Marschark and Patricia Elizabeth Spencer, 434-450. Oxford: Oxford University Press, 2003.

External links

• Cochlear Implants Information from the National Institutes of Health (NIH).
• Brightsurf Science News - Cochlear Implant Restores Hearing To Patient With Rare Genetic Disorder
• Increased use in the elderly.
• NPR Story about improvements to improve the processing of music. Includes simulations of what someone with implants might hear.
• Tuning In PBS article about advances in cochlear implant technology with simulations of what someone with each type of implant would hear.
• My Bionic Quest for Boléro (Wired, November 2005): Author Michael Chorost writes about his own implant and trying the latest software from researchers in a quest to hear music better.
• Rebuilt: How Becoming Part Computer Made Me More Human A memoir of getting a cochlear implant, writen by Michael Chorost and published in 2005.
• Rationale for bilateral cochlear implantation (PDF)
• The Let Them Hear Foundation assists individuals with appealing health insurer denials for cochlear implants
• Cochlear implant case study
• Cochlear Implant Info
• "For Some Who Lost Their Hearing, Implants Help", Jane E. Brody, New York Times, October 3, 2006.
• Hear Again, by Arlene Romoff The compelling, true story of how a late deafened adult regained communication with the "hearing" world
• [14]Cochlear Implants, Cochlear Implant Surgery, Benefits of Cochlear Implants, Information for Patients
• "What Does Health Insurance Pay for Cochlear Implants?" A non-commercial information resource presented by Otologic Reimbursement Management
• Hear Again - an Implantees BlogA blog by an implantee, that gives a vivid, descriptive picture of what it is like to have a Cochlear Implant
• Cochlear Implants and Their Effects on the Deaf Community