Seriously? I don't think it began back in 1980s... if so, it sure surprises me.
1950, Lundberg performed one of the first recorded attempts to stimulate the auditory nerve with a sinusoidal current during a neurosurgical operation. His patient could only hear noise. However, a more detail study followed in 1957 by Djourno and Eyries, provided the first detailed description of the effects of directly stimulating the auditory nerve in deafness. In their study, the stimulus appears to have been well controlled. Djourno and Eyries placed a wire on the auditory nerves that were exposed during an operation for cholesteatoma. When the current was applied to the wire, the patient described generally high-frequency sounds that resembled a “roulette wheel of the casino” and a “cricket”. The signal generator provided up to 1,000-Hz and the patient gradually developed limited recognition of common words and improved speech-reading capabilities. The patient was found able to discern differences in pitch at increments of 100 pulses and was found able to distinguish words such as “pap’, mamn”and “allo”.
In 1964, Doyle et al., reported inserting an array of electrodes into the cochlea of a patient with total perceptive deafness. The electrodes were designed to limit the spread of the electrical field and were stimulated in sequence with threshold square waves that were superimposed with speech signals. The four electrodes were not especially implanted to take advantage of the spatial distribution of the auditory nerve fibers responding to different frequencies, and the result obtained was only satisfactory. However, it was significant that the patient was able to repeat phrases.
Yet another researcher, Simmons (1966) provided a more extensive study in which electrodes were placed through the promontory and vestibule directly into the modiolar segment of the auditory nerves. The nerve fibers representing different frequencies could be stimulated. The patient was tested to assess the effect of alterations in the frequency and intensity of the signal. The subject demonstrated that in addition to being able to discern the length of signal duration, some degree of tonality could be achieved.
The clinical applications of electrical stimulation of the auditory nerve were refined by House (1976) and Michelson (1971) through scala tympani implantation of electrodes driven by implantable receiver-stimulators. Dr. William House observed the percepts of patients when small electric currents were introduced to the promontory during middle ear procedures under local anesthesia. But technical barriers proved frustrating. During the early sixties, House implanted several devices in totally deaf volunteer patients. Although these were rejected due to lack of biocompatibility of the insulating material, that they worked for a short time provided optimism towards a solution for sensorineural deafness. (House testimonial). House teamed up with Jack Urban, a very innovative engineer, to ultimately make cochlear implants a clinical reality. The new devices benefited from the increasing capabilities for microcircuit fabrication derived form space exploration and computer development.
RAPID PROGRESS: The commercial marketing of Cochlear Implants
In 1972, a speech processor was developed to interface with the House 3M single-electrode implant and was the first to be commercially marketed. More than 1,000 of these devices were implanted between 1972 to the mid 1980s. In 1980, the age criteria for use of this device was lowered from 18 to 2 years. ). During the 1980’s, several hundred children had been implanted with the House 3M single channel device. The FDA formally approved the marketing of the 3M/ House cochlear implant in November 1984. By the late eighties, virtually all of the major concerns about the long-term success and safety of cochlear implants were largely resolved.
During this same period, work outside the United States was progressing, most notably in Australia where Clark and colleagues were developing a multi-channel cochlear implant that, in the last half of the eighties, was to become the single-most used implant in the world under the name "Nucleus Multi-channel Cochlear Implant". Multiple channel devices were introduced in 1984, and enhanced the spectral perception and speech recognition capabilities compared to the single-channel device, as reported in large adult clinical trials.
