February 25 marks the World Day dedicated to the device that has changed the prospects for the treatment of severe and profound deafness. In babies, it can restore hearing
Intuition, experimentation and even a bit of luck. Scientific revolutions often arise from these ingredients. A recipe that also applies to the cochlear implant, whose World Day is celebrated on 25 February. In the case of this technology, the definition of silence revolution could well be used, because has really overturned the therapeutic horizon of severe and profound sensorineural deafness both in adults who have lost hearing in the course of life, and in children born deaf. To the latter, if identified in time, the cochlear implant totally restores hearing. And in the former, it helps to improve it significantly.
History
Yet little is said about this milestone in medical science. Perhaps because 65 years after the intuition of an ENT surgeon, Charles Eyries, and an electrophysiologist, Andr Djourno, take it for granted. In 1957 the two Frenchmen inserted a copper wire into the auditory nerve of a deaf person and discovered that the man could perceive sounds when the nerve was stimulated by the current. Thus they laid the foundations for the construction of the plant, which was perfected years later. Some of the later advances were made by the American William F. House professor of otologyconsidered the father of the cochlear implant, who in 1961 made the first single-channel device in the world. Graem M. Clark, in Australiainstead, he promoted research on multichannel cochlear implants in 1978.
Doctor House
House was an absolute genius, incredibly modest. I learned a lot from him, both from a surgical and a human point of view, says the professor Mario Sanna, director of the Otological Group center in Piacenza, who was a student of House and among the first in Italy to create cochlear implants. The pinch of luck, House had it when, as Professor Sanna recounts, a patient brought him a newspaper parcel. The news reported that in Paris a certain ENT surgeon together with an electrophysiologist had treated a completely deaf patient with an electrical stimulus and this patient had heard. House read the article and immediately the light went on.
Operation
From that prototype to today’s sophisticated systems, a lot of technological innovation passed under the bridge. How do they work? There is an external part that acts as a hearing aid, receives the sounds and “forwards” them through a transmitter which in contact with the internal part of the device through a magnet. The internal part receives these sounds, transduces them into electrical impulses that are sent to the acoustic nerve through a multielectrode inserted in the cochlea. The electrical energy passes through the acoustic nerve and then, through the cochlear pathwayit reaches the ventral dorsal nucleus and from there it reaches the cerebral cortex which processes the signal, explains Professor Sanna.
Early intervention
Obviously, the sooner deafness is noticed, the earlier the implantation and the higher the success rate. The auditory central nervous system has a plasticity – explains the professor Stefano BerrettiniProfessor of Otolaryngology at the University of Pisa and director of the Orl, University Audiology and Phoniatrics of the Pisan University Hospital -. If a child does not hear in the first 5-7 years of life, he does not develop language areas. Therefore, the sooner a stimulation can be given and more adequate, the better the auditory pathway develops and consequently the areas not only linguistic but also all the other associated areas.
The intervention and the post-operative course
How is the surgery performed to implant the device? A small, three-centimeter behind-the-ear incision is made then the mastoid bone is milled, the round window is found, the electrode is inserted, and then the surgery is concluded. From the conceptual point of view very banal and a very simple intervention in expert hands, explains Professor Mario Sanna. What is the postoperative course? After or two days of hospitalization, the patients go home. Then he expects the wound to heal, the external part is applied, after about a month, and the electrodes are activated. With particular electrophysiological techniques it is possible to understand which electrodes are working. In adults there is no need for rehabilitation except in some cases. On the other hand, rehabilitation is much longer in children.
A quale et si pu
International guidelines today generally agree on the need for bilateral cochlear implantation, ie on both ears, in the most profound deafness. Moreover l
’et of implant execution decreased from 12-18 months of life to 10-12 months in the most severe deafness. As for the young, the candidates for implantation are of different types. All children deaf at birth, with severe or profound deafness, and which are now commonly identified with neonatal screening. That is, those with a birth deficit greater than 90 decibels. And then those who instead develop acquired deafness, see meningitis, and those who have moderate or mild deafness that progress and at some point do not have a more significant benefit from the hearing aid but need to switch to the cochlear implant, adds Professor Berrettini. also president of the Italian Society of Pediatric Otolaryngology. Adults too can benefit from a cochlear implant.
The results
Those who for any cause develop deafness, when it is possible to insert the electrode into the cochlea, reach optimal hearing levels. Even the elderly, so much so that there are no longer any age restrictions for the intervention. The cost of a cochlear implant of about 16 thousand euros is borne by the National Health Service in Italy, as well as the rehabilitation and sessions necessary for correct mapping. In our country about 1,400 are implanted a year (2019 figure), between adults and children. Worldwide, the US FDA has counted 736,900 registered devices implanted until December 2019. The future? Implants less and less invasive and totally implantable, that is, without the external plate. The hope? Prevent deafness thanks to cochlear genetics and cochlear stem cells. In 50-60 years, maybe. But I hope I’m wrong, says Professor Sanna.
February 27, 2022 (change February 27, 2022 | 12:05)
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