France, the United States, Austria and Australia
all played a key role in the development of cochlear implants. Yet the pioneering role of French researchers was often minimized or overlooked, sometimes for base commercial reasons.
With hindsight, this “francophobia” appears somewhat risible.
Most English-speaking authors tended to cite Volta first and foremost, no doubt because he was Italian and despite the fact that he himself had never performed a cochlear implant.
The French researchers C. Eyriès and A. Djourno are cited in second place
although some "historical reviews" implied that
they were not French but rather " Franco-Algerian ”.
Yet France played a crucial role in developing the necessary technology: indeed,
the patent granted to Bertin in 1977
determined all the procedures that would be used by other international teams:
in order to avoid falling foul of the patent, they were obliged either to keep using outdated procedures,
such as transcutaneous electrical pedestal or extracochlear implantation;
more often, they opted to provide the patient with only partial auditory information,
Since that date,
the claims made in this French patent have been exploited by all implant manufacturers.
The history of the multichannel cochlear implant thus begins, and continues today,
with pioneering French research.
HISTORY OF THE FRENCH MULTICHANNEL COCHLEAR IMPLANT
In this brief summary, I will only cite those international researchers, who made an essential contribution to the development of the cochlear implant.
The story can be divided into three periods, namely :
FIRST CLINICAL TRIALS: 1951-1976
At the beginning of this period the prototype cochlear implant had only one electrode.
The first implant was performed in 1957 in Paris, by Charles Eyriès, a Parisian otologist and anatomist. The device was designed and manufactured by André Djourno, a professor of medical physics, also in Paris.
Astonishingly, the first auditory results achieved by Djourno and Eyriès were obtained by chance.
Indeed, the two researchers’ initial aim had been to mobilize the fixed facial traits of a patient with cholesteatomas in both ears, which had been complicated, probably many years previously, by bilateral facial paralysis. Djourno, who was studying remote muscle stimulation by electromagnetic induction, manufactured an implant consisting of a pair of coils, one of which was connected to an electrode. What appears to have happened is that Eyriès touched the electrode to a branch of the auditory nerve, laid bare by the abscess.
Read (in french) the princeps publication of Djourno & Eyriès
This had no effect on the facial nerve, because the paralysis was likely too long-standing,
but the patient heard a sound...!
The two authors had the prescience to document in detail their electroacoustic observations over a period of several weeks, finally publishing them in a French scientific journal, la Presse Médicale.
Thus began the role of France in the development of cochlear implants.
DJOURNO A., EYRIES C. - Auditory prosthesis by means of a distant electrical stimulation of the sensory nerve with the use of an indwelt coiling]. Presse Med. 1957, Aug 31;65(63):1417
True, the two Parisian researchers did not pursue their efforts when the device failed after less than a month. But had they not published their astonishing observations, William House might not have dared attempt to overcome total deafness.
Little further work was done by the French researchers, as Djourno took little interest in sensory stimulation.
In 1961, William House (1923-2012), a Los Angeles otologist already renowned for his surgical innovations in vertigo and neuroma, took up from where Eyriès had left off. He standardized the operation by placing the electrode in a stable position, threading it through the round window in the cochlea. He developed a reliable device and started to implant it in a growing number of patients.
His system, which stimulated all the auditory nerve fibers, only allowed its recipients to recognize the voicing and rhythms of speech. But it lifted them out of the total silence in which they had hitherto been confined, and the basic sounds they perceived helped to improve their lipreading.
House’s results created not only astonishment and also enthusiasm but also sharp criticism among the worldwide ENT community.
1/ House’s critics accused him of endangering healthy cochlear structures, or the few remaining auditory nerve fibers. His work triggered a series of studies focusing on the safety of the implanted materials, in which U.S. researchers and the Australian clinical team led by G. Clark rapidly became involved :
Clark GM, Hallworth RJ, Zdanius K. A cochlear implant electrode. J Laryngol Otol. 1975, Aug; 89(8): 787-92.
To overcome these objections, some teams proposed to insert the electrode along the outside of the cochlea, in extra-cochlear position. But the results were not as good as those obtained with House’s system.
Doubts concerning the safety of intracochlear electrodes persisted for more than 12 years. In Aachen, Deutschland, Paul Banfai developed an extracochlear multichannel system that gave interesting results; but the death of its chief proponent halted further development.
Banfai P, Karczag A, Kubik S, Lüers P, Sürth W. Extracochlear sixteen-channel electrode system. Otolaryngol Clin North Am. 1986 May;19(2):371-408.
2/ The main weakness of House’s single-channel implant was that it did not allow patients to understand the spoken word without lipreading. Physiologists came to the conclusion that it was crucial to provide individual, simultaneous stimulation of several cochlear nerve fibers, each carrying different sound frequencies, but the feasibility of such a system was doubtful.
In 1964, B. Simmons (1930-2008) in Stanford, conducted animal studies in which he implanted several electrodes at different parts the cochlear nerve, near the internal auditory canal, and obtained, for eachelectrode, a differentiated frequency response in the colliculus of the auditory brain stem.
R. Merzenich then demonstrated in macaques that stimulation of each electrode triggered differentiated responses in the auditory cortex.
Simmons FB, Mongeon CJ, Lewis WR, Huntington DA. Electrical stimulation of acoustical nerve and inferior colliculus. Arch Otolaryngol. 1964 Jun; 79: 559-68.
Merzenich MM, Brugge JF. Representation of the cochlear partition of the supérior temporal plane of the macaque monkey. Brain Res. 1973, Feb 28; 50(2): 275-96.
However, surgical positioning of the electrodes in this way was impossible in humans. Some authors tried to thread a bundle of electrodes of different lengths through the cochlear apex. House himself attempted the same approach through the round window. The results were disappointing, however, because whenever a given electrode was stimulated, the labyrinthine fluid diffused the electrical impulses to all the auditory nerve fibers. Furthermore, the apparatus needed to generate this multiple information was far too bulky in the 1960s.
Thus, in 1965, House opted for a single-channel system,
that he continued to implant until 1995 and beyond...!
House reported his experience at the 1972 International Collegium ORL-AS conference, attended by Alain Morgon, a French ENT surgeon, Member of the Collegium.
Morgon, whose focus was childhood deafness, immediately grasped the potential of this level of hearing, however modest, to overcome some of the problems associated with deaf-mutism. He contacted Robert Charachon, from Grenoble, and myself and suggested we take a look at this new technique.
He knew that I had worked on neuroanatomy with Charles Eyriès
between 1960 and 1965,
and that Bernard Meyer, who was soon to become my assistant at Saint-Antoine Hospital in Paris, had close personal ties to Eyriès.
Morgon was also aware that Charachon had established an excellent working relationship with researchers at the CEA (Commissariat à l' Energie Atomique), the French nuclear research institution of Grenoble.
We all knew of Eyriès early work and were naturally intrigued by the results obtained by House.
Although House managed to provide profoundly deaf patients with some very valuable auditory information that already made a significant impact in their daily lives, his device was clearly inadequate as the patients were still unable to understand speech without lipreading.
Back at St. Antoine hospital in Paris, we immediately started to develop an improved device, because
we had 2 chances:
1-) When I was medical student I had a friend, Patrick Mac Leod, who, in addition to become a medical doctor, became also a scientist
2-) By chance, I had acquired some experience in surgical treatment of traumatic facial palsy and vestibular neurectomy by supra petrosal approach.
I contacted P. MacLeod : twenty years later, he was now an MD, a physiologist specializing in sensory function, and also Research Director at the Ecole Pratique des Hautes Etudes, which was located in the Collège de France in Paris. We discussed about the perception and discrimination of frequencies produced by electrical stimulation of auditory nerve fibers.
He agreed that, because of the refractory period of the auditory nerve, a single-channel implant was unlikely to provide frequency discrimination beyond 300-500 Hz, or maybe 800 Hz, but certainly no higher.
It was clear that a high-performance cochlear implant would need to have several electrodes, and that the easiest approach was to divide them along the frequency gradient of the cochlear tube.
They would also have to be electrically isolated from one another, except at their extremity. MacLeod formulated two absolute requirements:
1/ Long-term safety. To avoid iatrogenic nerve fiber degeneration, it would be essential to avoid direct contact between the electrodes and nerve fibers, meaning they would have to be located in the scala tympani of the cochlear tube.
2-It would be crucial to avoid diffusion of the electric current via labyrinthine fluids along the entire fan of cochlear nerve.
Shortly after, in May 1973, Patrick Mac Leod and I, we attended the international ENT conference in Venice with MacLeod. Robert Michelson (San Francisco) reported perceptual results obtained in humans with four electrodes of different lengths
in Eshrahi & alL p.1969
stimulated by four pairs of solenoids, which sat like hair curlers on the scalp.
Michelson confirmed to us that the biggest difficulty was keeping the electrodes isolated from one another.
It was clear to us that Point n°1 had been dealt with satisfactorily by existing American and Australian studies
We thus turned our attention to Point n°2,
discussing it at length one sunny afternoon on the Grand Canal
while sketching our ideas on the paper tablecloth of a trattoria.
Suddenly, we both hit on the idea of drilling small windows
in the underside of the first and second turns of the cochlea
and inserting one or two electrodes
facing upstream and downstream in the scala tympani,
Through 8-10 windows created tangentially on the two turns of the cochlear tube,
between the facial nerve and the internal carotid artery
we could introduce up to 12 electrodes
separated by several small blocks of silastic pushed into each hole after the electrodes.
We decided first to connect the electrodes to a transcutaneous Teflon contact and, using an easy-to-construct series of filter banks, to deliver the energy variations contained in different frequency ranges of the auditory information.
Chouard CH, MacLeod P. La réhabilitation des surdités totales: essai de l'implantation cochléaire d'électrodes multiples. La Nouvelle Presse Médicale. 1973; dec 8;(2): 217-33.
After verifying the feasibility of this approach in the laboratory, we tested it on volunteers with petrous bone fracture resulting in unilateral total deafness and facial paralysis on the same side:
Ethically, it was clear : surgery was absolutely essential to treat the injury to their facial nerve.
I asked the patients for their permission to use our technique to test the functional status of their ear, which was, in theory, "lost", and then to spend a few hours with us for postoperative tests. We warned them that, even if successful, it would remain a simple test procedure (their hearing on the opposite side was intact).
All the patients we approached gave us their informed consent.
The percutaneous plugs of our first patients (1973-1975)
Within a few months, tests on three of the patients showed that selective stimulation of six or eight electrodes, inserted and isolated using our technique, allowed them to perceive different frequencies.
In late 1976, we were able to demonstrate the effectiveness of these cochlear partitions in terms of frequency discrimination and word recognition.
Chouard CH, MacLeod P. The Laryngoscope. 1976 Nov;86(11):1743-51.
On the basis of these encouraging results we tentatively treated five patients with acquired bilateral total deafness. In previous tests, these patients had perceived a variety of sounds, when we electrically stimulated the round window using the technique we had developed.
The transmitter of our first portable cochlear implant in 1974:
it allowed us to demonstrate the feasibility of our implantation method.
I warned the patients that their new-found hearing would be transient, as it would be necessary to devise a system that dispensed with the transcutaneous contacts. Nevertheless, most of them agreed to the procedure.
After relatively brief postoperative speech therapy, all the patients were able to recognize a certain proportion of words without lipreading.
Pialoux P, Chouard CH, MacLeod P. Acta Otolaryngol. 1976 May-Jun;81(5-6):436-41.
Early during this phase of our work, C. Fugain, an ENT physician and phoniatrician, joined the ENT Research Laboratory at St. Antoine University, together with B. Meyer, who described our experience in its MD thesis.
Contribution à la réhabilitation chirurgicale des surdités totales
par implantation intracochléaire d’électrodes multiples;
Thèse Médecine, Univ Paris VII, Paris, 1974, 94 pages.
Both these researchers played key essential roles in everything that followed.
We now needed to get rid of the transcutaneous connectors:
I felt they were unacceptable, contrary to some American authors, even in the late 1980s.
It was also unconceivable in my opinion to use a pair of solenoids per electrode, as Michelson had done. To solve this problem we needed technologies beyond those available my laboratory, and I therefore turned to Bertin, a private Research & Development Company, known for its initiative and versatility.
One of the most spectacular inventions of this innovative company was the Aerotrain.
The problem was as follows :
we had to send simultaneously six, eight or twelve different lines of information, perhaps more, and to ensure they all arrived at the inner ear together, at more or less the same time. As the analytical time of the cochlea is about two to five milliseconds, all this information would be perceived simultaneously, if it reached the ear within a shorter period.
The solution was therefore to cut the sound information into very short time units, and to transmit it so quickly that all eight or twelve segments reached the ear in less than 3 milliseconds.
The first microprocessors had started to appear, and MacLeod immediately realized their potential. It was he who suggested to Bertin’s engineer, J. Ricard, to use one of these new electronic components for transcutaneous sequential electromagnetic transmission of these multiple and simultaneous lines of information representing the sound environment.
It is now evident that Patrick MacLeod, thanks to his knowledge of electronics and physiology, was the true "inventor" of the multichannel cochlear implant.
A tabletop prototype was quickly constructed, but the untimely death of Jean Bertin in late 1975, led to a restructuring of the company and obliged us to wait until the summer of 1976, to receive the first six prototypes.
The first implantation took place at Saint-Antoine Hospital on Wednesday, September 22nd, 1976.
It was a nice morning.
I was assisted by Bernard Meyer who was Clinical Chief and also worked in my Laboratory.
The patient recovered his hearing the following day. So good were the immediate clinical results, despite the inconvenient size of the transmitter, that the other five patients were quickly implanted.
I attended the XI° World Congress on Otofhinolaryngology in Bunos-Aires (13th-19th of march) in order to present our first results. But that is by phone that I received from de Bertin's Patent Deprtment the authorization to speak...!,
Bertin asked us not to release our results, until they had made a patent application
(N° 77/0 7824),which occurred on March 16th, 1977),
published on july 1977and extended to USA on 10th of june 1980
This patent was extended in 1985 by 2 patents on the technical developments of the equipment and none of them was ever disputed.
Over the next twenty years,
thess documents was to influence all the procedures and research approaches
adopted by other international teams, who were forced to avoid its claims,
usually by sending only a portion of the available auditory information,
until the patent expired in 1997.
These results were soon published in several english and french papers :
in a few seconds, I will present an objective photography
demonstrating the role of France in the development of the multichannel cochlear implant
The overriding aims of the Saint-Antoine team were
|Chorimac-8 was carried on a shoulder strap, and was the size of a 2-liter oil can.|
These first transmitters were very large: In addition, they only had eight electrodes. Bertin described them as prototypes.
on "Amazon" site,
you may still read it for 8 euros
Given the increasing influence of the media in research funding,
I decided to write a book
with the aim of convincing potential donors.
I spoke about
the reasons of my desir
to prevent deaf-mutism,
as well as our research achievements
and hopes for the future.
And, above all, in September 1978 we organized at Saint-Antoine Hospital in Paris the first international Seminar on multichannel-cochlear-implants, focusing on
The seminar was very popular, being attended by all the pioneers (House, Eyriès and Michelson)
and also by researchers with little or no experience in the field.
Some of the participants at the closing dinner :
These photos taken at the closing dinner show the youthful faces of those who would soon become
the scientific or commercial directors of Austrian, Australian and American manufacturers.
Today = I am delighted to observe that
we had at least two "pupils" there,
at this Course,
who were going to take, in the future, a nice advantage of our teaching... ! Other remark = this Course in Paris has been the first of a long and exciting series of meetings or conferences devoted to the multichannel cochlear implant. The two following were also in Paris in 1983 and 1095, and the thirteenth will be held in München on next june 2014.
INDUSTRIAL DEVELOPMENT: 1977-1997
This phase of the development process was very lengthy and generated considerable controversy. It lasted some twenty years, until the Bertin patent expired and its powerful principles could be adopted by all manufacturers.
French development went through two phases:
1- 1977 to 1988 : Bertin’s disengagement
This first period was marked by commercial hesitation and procrastination by the new management team at Bertin, whose founder had died a year before our first implantation.
Thanks to new public funding, that these publications helped us to obtain, Bertin built us a few devices. But, for "financial" reasons, and despite advances in microprocessors and their engineers’ promises, these devices were identical to the prototypes and thus suffered from a major drawback: the prohibitive size of the transmitter.
All our activities helped us obtain new grants, including industrial grants to Bertin in order to construct a less bulky device, that we had been asking for since 1976. Yet, despite the additional funding, there lay ahead nearly three years of procrastination, broken promises and missed deadlines before we saw significant progress.
In 1979, Clarke and his Melbourne team, many of whom attended the Paris conference, published the following paper:
Tong YC, Black RC, Clark GM, Millar JB, O'Loughlin BJ, Patrick JF. A preliminary report on a multiple-channel cochlear implant operation. J Laryngol Otol. 1979 Jul; 93(7): 679-95.
The paper described the results they had obtained by sending, via three electrodes of different lengths that were easily threaded through the round window, information limited to voicing and speech first formant. The advantage of their device was that it provided more information than a single electrode, while requiring a transmitter smaller than ours.
For several months we spurred on Bertin’s engineers with these results.
We were absolutely certain of the theoretical superiority of our device, but we had to reduce the size of our 8-12 electrodes and simplify their implantation, so that other surgeons would adopt and promote it.
For some time, Bertin seemed convinced: the company finally provided us with a 12-channel device in 1982. The transmitter was now no larger than a book, but it was still huge by comparison with the simpler and more manageable systems developed in Melbourne.
An open Chorimac 12 device:
the settings could be adjusted by tweaking potentiometers with a screwdriver
The therapist could adjust the parameters of the 12 channels to each patient’s electrophysiological auditory characteristics. This innovation, advocated from the outset by MacLeod in view of our initial results, was clearly the way forward, even though it still required the use of a screwdriver and an oscilloscope.
This new feature was hailed at international conferences, yet newly created surgical teams did not choose the French implant, considering it too cumbersome and too complex to implant.
Indeed, our 12 electrodes initially had to be inserted one by one, in an operation lasting four or five hours.
We thus provided Bertin with numerous casts of the scala tympani, allowing the company to develop an electrode bearer enclosed in an electrically hermetic system, placing our 12 electrodes in a well-insulated bundle that could be easily introduced through the round window.
As a result, the operating time was significantly shortened.
Meanwhile, the Austrian team had also adopted the principle of multichannel intracochlear stimulation, closely imitating the Australian team’s efforts to bypass the French patent and gradually catching up with the Australians in terms of sales.
In 1983, I organized the Second International Conference in Paris.
The Australian and Austrian teams presented their results and showed off their latest devices: both were smaller than before, fitting in the palm of the hand or a pocket.
This alone ensured their success at the conference
and further underlined the only downside of the French implant, namely the size of its transmitter, which overshadowed its advantages and innovations.
After this conference we pressed Bertin to fully digitize our implant, something MacLeod has been seeking for years: he considered this the best way to miniaturize the transmitter and to automate its adjustment. And it was clearly feasible, given the rapid advances being made in electronics. To make sure that Bertin would comply quickly with our request, I went about seeking the funds that Bertin’s directors said they needed
It started to get easier to fund our research.
Evaluation committees, convinced by our patients’ testimonies of the quality of the French system, ensured that Bertin received public funding for the necessary miniaturization and persuaded the social security system to fund an increasing number of devices.
This miniaturization became all the more urgent when, in 1984, the U.S. Food and Drug Administration approved the Melbourne implant for use in adults. The Australian device enjoyed well-deserved popularity and was implanted in many surgical centers worldwide, including in France.
The Bertin patent claims seemed more and more pertinent:
they were bypassed in Melbourne and Innsbruck,
and even challenged by some American researchers:
Parkin JL, Eddington DK, Orth JL, Brackmann DE. Speech recognition experience with multichannel cochlear implants. Otolaryngol Head Head Neck Surg. 1985, Oct; 93(5): 639-45.
Wilson BS, Finley CC, Farmer JC Jr, Lawson DT, Weber BA, Wolford RD, Kenan PD, White MW, Merzenich MM, Schindler RA. Comparative study of speech processing strategies for cochlear implants. Laryngoscope. 1988 Oct;98(10):1069-77.
These American researchers continued to use outside pedestals, claiming they enabled them to optimize the signal processing. In practice, they were obliged to provide all the sound information -- in other words to apply MacLeod’s proposal, one of the French patent claims.
However, it allowed these researchers to challenge Bertin’s strategy for many years, mainly for the commercial reasons described below.
Our relationship with Bertin changed radically when we asked the company to digitize our device.
Technical discussions with Bertin’s engineers, which had been ongoing since the beginning of our collaboration, were not longer possible.
Citing “trade secrets”, Bertin refused for several years to provide us with any information on the advancement of the project. Then, one day, we received a huge new model, almost as bulky as our previous device, that was in fact a simple mock-up of a prototype...!
What had happened to the industrial grants the company had obtained to fund our project...? There had clearly been a massive waste of money! I never discovered the real reason...!
This was in 1987, and the Australian system had really taken off. Its signal processing had expanded, now featuring not only voicing an the first formant, but also the second vowel formant.
Its efficiency had thus improved, and the Australians had made a huge marketing effort.
This implant, followed by the Austrian and American implants, started to be used widely in many French and foreign centers.
It was no longer possible to vaunt the merits of the French implant.
One autumn day in 1989...a sad day.... we began to implant our first foreign devices...!
and owingto this decision, the clinical and technological expertise of our clinical department and laboratory continued to grow.
in case of profound neo natal deafness.
The effect of the acoustic nerve chronic electric stimulation upon the guinea pig cochlear nucleus development.
The effect of the acoustic nerve chronic electric stimulation upon the guinea pig cochlear nucleus development.
Chouard CH, Meyer B, Josset P, Buche JF.
Acta Otolaryngol. 1983 May-Jun;95(5-6):639-45
download the reference(french)to read the discussion
based on the strength of the Bornn's method which, twenty years before,I learnt with Charles Eyriès,
has never been discussed,
but has been followed by similar papers
based on cells counting.
2- 1987 to 1997 MXM-Neurelec takes over the Bertin patent and spurs technological development
Almost at the same time, in 1987, Bertin sold its patent rights to a small start-up in Antibes, MXM-Neurelec.
I immediately informed the company directors that our cochlear implant with its bulky transmitter was totally unsuitable. I also told them that, with their support, we were in a position to revisit the principles underlying the Bertin device.
Our work on cochlear implants had allowed my laboratory to grow.
We asked MXM-Neurelec to miniaturize our implant and, above all, to make it more versatile than the still-born device Bertin had expected us to adopt.
Jacques Génin, a friend of mine at X-Telecom, joined the team around this time. He was bored working for the administrative authorities, to which he had returned after many years conducting research in the Lannion and Grenoble laboratories, a period during which he had helped to develop Minitel, the French forerunner of the Internet.
Jacques Génin took great pleasure in applied research, and his friendly advice was invaluable. In addition, the contacts I had maintained for several years with a number of engineering schools, and the school of Biological and Medical Engineering at Créteil University, now proved invaluable.
Two students in these schools, Jean-Marc Leveau and Philippe Dubus, came up with an original idea that finally enabled us to achieve our goals. Using the "trick" they had discovered, we were easily able to build a prototype of the new fully digitized French cochlear implant. The details of this invention are unimportant: the basic idea was to place two microprocessors in series.
It may seem nothing special today, but it remained a closely guarded industrial secret for many years because it was not patentable. It was of course quickly copied, yet advances in microprocessor technology rendered it obsolete within a few years.
The prototype made in our laboratory was turned over to MXM. Within a few months, after checking the design and adding the necessary security features, MXM produced an entirely new device in early 1992. It was smaller than its closest (Australian) competitor and, above all, fully programmable.
MXM named it Digisonic.
Its implanted receptor was less bulky than that of its competitor, yet contained the receiving antenna within its ceramic capsule.
The first electrode bearer of the Digisonic implant
The electrode bearer consisted of small juxtaposed chambers, and the bottom of each chamber contained the electrode, greatly improving the isolation between the different channels.
Additionally, each electrode had a very rough sintered surface, which increased the contact area between the electrode and the living tissue, thus allowing safe delivery of a large amount of current, if necessary. All the chambers articulated with one another like railways cars, facilitating their introduction into the cochlear tube.
One day, JM Leveau and P Dubus hit on the original (but unpatentable) idea of placing two microprocessors in series in order to create a fully digital implant. The prototype, made in Saint-Antoine, was given to MXM Neurelec, who used it to produce an entirely new device a couple of years later. I will not go into the details of the Digisonic device, but the work conducted by MXM immediately put France back at the forefront of cochlear implant technology. Most of the innovations that accompanied or followed the total digitization of our implant have inspired other manufacturers.
After 1992, it became clear that manufacturers of the different cochlear implants produced worldwide were gradually adopting their signal processing strategy to the technology of the Bertin patent, i.e. providing patients with all the available auditory information in a sequential manner.
The American implant developed on the California coast also transmitted all the information but used a few clever ruses and restrictions to avoid falling foul of the French patent.
Wilson BS, Finley CC, Farmer JC Jr, Lawson DT, Weber BA, Wolford RD, Kenan PD, White MW, Merzenich MM, Schindler RA. Comparative study os speech processing strategies for cochlear implants. Laryngoscope. 1988 Oct; 98(10):1069-77.
Wilson BS, Finley CC, Lawson DT, Wolford RD, Eddington DK, Rabinowitz WM. Better speech recognition with cochlear implants. Nature. 1991 Jul 18; 352(6332): 236-238.
The Australian manufacturer then also changed its strategy, providing all the auditory information but only retaining the channels with maximum energy. This restriction also avoided the terms of the Bertin patent. Eventually, however, the French patent was unquestionably copied, and Bertin engaged full-blown legal proceedings in 1997, with seizure of its rival’s materials and bailiff involvement. This was just before the patent was to fall into the public domain. However, following protests in a number of surgical centers, Bertin quickly abandoned the charges: the cost of the proceedings and the necessary expert reports would have far exceeded any financial return the company might expect to gain.
All device manufacturers have since applied the principles of the Bertin patent, as defined by P. MacLeod. In France, MXM Neurelec has ensured the continuous technological improvement of our cochlear implant, based on feedback from clinicians, researchers and industrialists.
3- THE CONTEMPORARY PERIOD : 1998 to present
Almost all the hopes and expectations that drove our initial research have now been realized.
I will recall here France’s main technological and clinical contributions to the field.
Bilateral implantation is now commonplace in both adults and children, thanks to the efficiency of current devices, their miniaturization, and their lower relative cost.
However, it should be remembered that W. House had been performing dual implementation of his single-channel system since 1975.
Adaptation of the device’s electronics to the particularities of brainstem implants has of course contributed to the success of this particular method for rehabilitating total deafness.
Grayeli AB, Kalamarides M, Bouccara D, Ambert-Dahan E, Sterkers O. Auditory brainstem implant in neurofibromatosis type 2 and non-neurofibromatosis type 2 patients. Otol Neurotol. 2008 Dec; 29(8): 1140-6.
Vincent C, Zini C, Gandolfi A,Triglia JM, Pellet W, Truy E, et al.. Results of the MXM Digisonic Auditory Brain Stem Implant Clinical Trials in Europe. Otology & Neurology, 2002, 23: 56-60.
Two advances are particularly dear to me.
1-) First of all, the ability of cochlear implants to prevent deaf-mutism by very early implantation of young children with bilateral cophosis is now well documented, and the opposition of the deaf community, which I discuss below, has finally subsided in France, largely thanks to the efforts of A. Morgon and the following reviews:
F. Legent. Morgon A, Beger-Vachon C, Chanal JM, Kalfoun G, Dubreuil C. Cochlear Implant: experience of the Lyon team. Acta Otolaryngol Suppl. 1984; 411: 195-203.
Legent F. Le dépistage de la surdité dans la période néonatale précoce. Bull. Acad. Natle. Méd. 2008, 192, n° 6, 1233-1235.
The St. Antoine laboratory also started to work on coupling cochlear implants to conventional hearing aids.
2-) Even before the digital technology used in the cochlear implant made by MXM was adopted by all manufacturers, the idea came to us in the late 1980s to exploit simple sound-amplifying devices; indeed, their technology had hardly benefitted from advances in computer technology: in particular, they did not yet include filter banks allowing their amplification to be adapted to the frequency characteristics of the individual user’s deafness.
We advised cochlear implant manufacturers, and particularly MXM-Neurelec, to exploit hearing-aid manufacturers’ expertise in ergonomics, microphone technology, and ambient noise attenuation. There was no need for a patent, but it was necessary to move quickly because the idea was so simple! Thanks to J. Génin, the testbeds set up in the Saint-Antoine laboratory were so promising that we set about finding a company capable of launching the first hearing-aid factory in France.
Alcatel-Alsthom rapidly became interested, and we were finalizing the roadmap with their engineers when, in the summer of 1995, a change in the company’s strategy led to the project being abandoned.
Shortly afterwards I was contacted by Siemens France, who had also got wind of our project. The concept worked at our first attempts: 3 channels, then 5, then 12: speech intelligibility increased with the number of channels. This technology is now used by all manufacturers and in most hearing aids.
Chouard CH. L'appareillage des surdités de perception: étude d'une prothèse auditive numérique à 7 filtres entièrement programmables. Bull. Acad. Natl. Med. 1997; 181: 275-286.
Gradual extension of the indications of cochlear implants to severe but incomplete deafness led to the development of mixed cochlear implants -- a spectacular but still controversial marriage of the two technologies. Developed at a very early stage by the Austrian team, the mixed cochlear implant was designed for patients with more or less early-onset perceptive hearing loss, in which low frequency perception was relatively preserved but high-frequency perception was severe altered and conventional devices were ineffective. The resulting device was a hermaphrodite: it comprised a mechanical amplifier for low frequencies and also a small electrical implant theoretically reserved for high frequencies. The physiological mode of action and clinical indications of this interesting device are still debated.
The story of the cochlear implant is far from over: fully implantable cochlear implants are already in the pipeline, as we had foreseen many years ago . The two main problems are percutaneous transfer of the sound signal to the internal microphone, and the duration, number of charging cycles, and safety of the implanted battery.
Chouard CH, Genin J, Mac Leod P, Meyer B, Dubus Ph, Leveau JM. Présentation du Prototype d'une Prothèse Cochléaire entièrement implantée. Ann. Oto-Laryngol.(Paris). 1990; 107: 424-429,
These new cochlear implants will soon be here, as similar hearing-aid prototypes are already being evaluated. In addition, robots are being developed to place the electrode carrier without damaging intracochlear bone, by drilling a simple well through the mastoid.
Miroir M, Nguyen Y, Szewczyk J, Mazalaigue S, Ferrary E, Sterkers O, et al. Evaluation du prototype d’un système robotique pour la microchirurgie de l’oreille moyenne. Comm. 116° Congrès de la Société Française d’ORL et de Chirurgie de la Face et du Cou. Colloqium (Paris) Octobre 2009.
Advances in nanoelectronics will lead to further advances, revolutionizing both our environment and the treatment of deafness. It may eventually be possible to eliminate polymorphic background noise, which is still a problem for so many deaf people, in real time.
Over a period of 28 years, from 1973 to 2001, the university research laboratory I created in 1966 alongside the ENT clinical department of Saint-Antoine hospital in Paris did everything within its capacity to develop and promote an efficient and reliable cochlear implant.
I mention above the strict ethical rules we followed, which obviated the need for an ad hoc committee.
And I have been able to inculcate the strictest Hippocratic principles to three successive generations of surgeons.
Over the years, our work was influenced by three main factors, namely:
- the precious role of the scientific environment,
- the negative impact of commercial competition on efforts to conduct international multicenter comparisons of device efficacy
- opposition by the deaf community.
1- The role of the global scientific environment
Our early research was strongly criticized by some individuals, most of whom were not specialists in the problems of deafness. But we were encouraged by the fact that several other French and foreign teams were seeking to develop a cochlear implant.
Together with our own work, these teams’ research demonstrated to the rest of the medical community the potential benefits of this new type of auditory prosthesis. Although most of these teams eventually abandoned the field, they remain an integral part of the history of the cochlear implant.
This is why I must mention the work of another Paris team, led by B. Frachet, as well as the teams headed by René Dauman in Bordeaux, Paul Banfai in Aix la Chapelle (Aachen-Germany), E. Douek in London, and B. Ferron in Quebec. A good deal of work was done in China, from a very early stage.
I must also stress the importance of Robert Charachon’s research work and Alain Morgon’s clinical expertise. Between 1972 and 1977, these two authors published many papers that helped to define the clinical and instrumental indications of cochlear implants.
The work of the Grenoble school, and notably the medical thesis of Bernard Accoyer, demonstrated the technical viability of the French project. Although the Grenoble CEA laboratory was unable, at least at that time, to provide the necessary material solutions, its efforts at least showed our critics that the research conducted at St. Antoine was not completely Utopian.
Frachet B, Vormes E, Verschuur HP, Harboun-Cohen E, Despreaux G. Electrical stimulation of the fenestra ovale. Perspectives. Ann Otolaryngol Chir. Cervicofac. 1988; 105(8): 597-600.
Négrevergne M, Dauman R, Lagourgue P, Bourdin M. The Prelco mono-canal extra-cochlear implant. Rev Laryngol Otol Rhinol (Bord). 1988; 109(3): 273-6.
Fourcin AJ, Rosen SM, Walliker J, Douek EE, Clark GP, Moore BC. Electrical auditory stimulation in the management of profound hearing loss. J Laryngol Otol. 1979 Apr; 93(4): 427-8.
Bergeron F, Ferron P, Desgagné M. Cochlear implantation in Quebec city: auditory performance in a recently trained patient. J Otolaryngol. 1989 Feb;18(1):7-23.
Chouard CH, Pialoux P, Mac Leod P, Charachon R, Meyer B , Soudant J., Morgon A . Stimulation électrique du nerf cochléaire chez l’homme. XII° Congrès International d’Audiologie, Paris 1974.
Accoyer B, Charachon R, Richard J. Electrocochleography. First clinical results. J Fr Otorhinolaryngol Audiophonol Chir Maxillofac.1974 Jun; 23(6): 499-505.
Accoyer B. Approche théorique et clinique du traitement des surdités totales par implantations chroniques d’électrodes intra-cochléaire multiples; Thèse Médecine, Grenoble, janvier 1976, 184 pages.
2- The negative impact of commercial competition on international multicenter comparisons of implant efficacy.
In the late 1980s, several studies were conducted to compare the effectiveness of the four types of implant used in various countries. Researchers and industrialists no longer debated the relative merits of single- and multichannel systems, because the advantages of the latter were self-evident.
The issue was now whether systems that provided all the auditory information, such as the French system and the American Eddington apparatus with their transcutaneous contacts,
were equivalent or perhaps superior to systems that provided only the most relevant information, i.e. the Australian and Austrian devices.
The comparison was simple in theory:
it consisted of measuring the percentage of spoken words recognized by wearers, without lipreading, from lists of words selected among those used in the patient’s normal environment.
In practice, however, especially at that time, retrospective comparisons of this type were very difficult, as the patients themselves and the precise features of their deafness were never exactly the same.
In addition, different teams used different selection criteria. None used the same pre-operative tests, for example to determine the percentage of fibers remaining in the auditory nerve. Electrical stimulation of the round window was used systematically prior to implantation in my department at Saint-Antoine, but only provided a very rough picture. In addition, the study populations were much too small for meaningful statistical analysis.
Finally, many of these international multicenter studies were marred by methodological flaws, some due to conflicts of interest. Modern-day editorial boards would shudder at some of the conclusions they reached !
3- Opposition of the deaf community
Paradoxically, early development of the cochlear implant ran into violent opposition from the “deaf community” worldwide. It was particularly intense in France, possibly because we had clearly stated our intention to prevent the disability associated with deaf-mutism.
Indeed, work done in our laboratory in 1982 demonstrated that the cochlear implant could prevent atrophy of the brain’s auditory centers. It also explained the poor neuroanatomical results of late implantation in deaf adults: in animals, this atrophy could only be prevented if the device was implanted before a critical age.
Chouard CH, Josset P, Meyer B, Buche JF. Effet de la stimulation électrique du nerf auditif sur le développement des noyaux cochléaires du cobaye. Ann. Oto-Laryng. (Paris) 1983; 100: 417-422.
This opposition to the cochlear implant among some healthcare professionals dealing with the consequences of profound deafness in children sometimes took on a rather extreme form, with hospital sit-ins and disruption of scientific meetings. The situation is less troubled today, although opposition persists in some quarters
Traitement de la surdité par pose d’implants cochléaires et du tronc cérébral.
Rapport de la Haute Autorité de Santé, mai 2007; 2 avenue du Stade de France – 93218 Saint-Denis La Plaine CEDEX; http://www.has-sante.fr
Comité Consultatif National d’Ethique pour les Sciences de la Vie et de la Santé. Avis N° 103. Ethique et surdité de l’enfant: éléments de réflexions à propos de l’information sur le dépistage systématique néonatal et la prise en charge des enfants sourds. Décembre 2007.
The concept of the "world of the deaf" is a late result of the efforts by Father de l’Epée to help integrate the profoundly deaf into hearing society.
Until the advent of the cochlear implant, the feeling of belonging to the “world of the deaf”, with its own language, often helped to palliate this handicap and allowed some individuals to flourish.
However, it also locked them into a ghetto with their own language and probably even their own physiological characteristics.
Indeed, colonization by visual stimuli of auditory brain areas that were not activated by sound during childhood probably explains the exacerbated sense of space acquired during adulthood by profoundly deaf children who had not been implanted.
This effect of brain plasticity is especially evident in the spatial precision required by the grammar of sign language in the speaker-listener relationship.
Buonomano DV, Merzenich MM. Cortical plasticity: from synapses to maps. Annu Rev Neurosci. 1998;21:149-86.
The patient association Le monde des sourds (world of the deaf) is one of the oldest patient groups. For some 20 years, development of the cochlear implant also turned it into one of the most violent. Surprisingly, however, many of the most vociferous opponents of the cochlear implant were not themselves profoundly deaf. What, then, were the leaders of this movement really defending? Why, when they themselves had either normal or adequately corrected hearing, did they refuse the same hearing capacity to the profoundly deaf children and adults they worked for, by teaching them sign language or transcribing audiovisual media? The answer is not clear.
Development of the cochlear implant began nearly half a century ago, and yet is still in its infancy.
These widely used devices will undergo further developments that we can barely imagine today.
But researchers, clinicians and industrialists should be aware of the pioneering work that brought us to this point.