Others also experimented with stimulation of the cochlea. In 1865, Duchenne de Boulogne reported a buzzing and ringing sensation, achieved by using alternating current. Much later, in the 1930s, Ernest Glen Wever, a Princeton University psychology professor, worked with Charles Bray during an otological research fellowship at Johns Hopkins Medical Center in Baltimore to record electrical potentials in the cochlea that paralleled sound stimulus waveform. This work suggested the possibility that replicating those potentials could restore hearing.
Explore This IssueApril 2013
In the second half of the 20th century, the work of neurophysiologist André Djourno and surgeon Charles Eyriès powered new interest in the direct stimulation of the auditory nervous system. While re-operating on a patient with recurring ear problems, Eyriès placed an electrode designed by Djourno on the stump of the patient’s auditory nerve. An induction coil with a return electrode was placed into the temporalis muscle. Post-operatively, the patient detected different sound intensities and small closed sets of spoken words. After that device and a second one failed, Eyriès refused to implant other patients, but the pair reported their findings in the French medical journal La Press Medicale. When the Los Angeles Times picked up the story, one of Dr. House’s patients read it and brought it to his attention (Anat Record. 2012;295:1967-1980).
The reports stimulated Dr. House to begin work on an auditory prosthesis. In 1961, he teamed with neurosurgeon John Doyle, MD, to place single-electrode gold implants in a few patients. These patients could identify words in small closed sets, but electrode rejection and fear of infection intervened.
In the mid-1960s, Stanford’s Blair Simmons, MD, then associate professor in the division of surgery (otolaryngology), implanted a six-channel device that used a percutaneous plug to enable stimulation of individual electrodes and was able to demonstrate that stimulating different areas of the cochlea could produce different pitch perceptions.
Robert V. Shannon, PhD, a research professor with USC Biomedical Engineering and director of the division of communication and auditory neuroscience at House Research Institute, noted that hermetic sealing technology, which was originally developed for the space program and later adapted by pacemaker companies, solved a major problem in CI technology. “Without a good hermetic seal, any implanted electronics only lasted a few months before leaking body fluids and shorting out.” Improvements in pacemaker technology spurred Dr. House to pursue development of a biocompatible CI. Starting in 1967, he partnered with engineer Jack Urban to produce the first hardwire five-electrode system and placed implants in three patients.