Lecture 1.1- Intro/Hx of CIs Flashcards
How does a CI work?
It bypasses the damaged peripheral hearing system and directly stimulates CN VIII.
Do recipients of CIs always have SNHL?
Not necessarily a strict SNHL.
- Can be mixed or more neural (ANSD)
What did Alessandro Volta discover?
Late 1790’s
- Described a “boom within the head” followed by a sound of “thick, boiling soup” after inserting 2 rods connected to a 50V electrical source into his ears
What did Guillaume-Benjamin-Amand Duchenne discover?
1855
Studied how neural pathways can conduct electrical pulses.
He experimented with alternating current in his ear.
Described sensation of “fly’s wings beating between a pane of glass and a curtain.”
What did Brenner discover?
1868
Used bipolar stimulation (one electrode in ear canal in saline and another in different location on body) in 1 subject.
Reported on effects of polarity, rate, and intensity of stimulus and placement of electrodes.
Reported that negative polarity stimuli produced better hearing and that correct electrode placement reduced negative side effects.
What was discovered at the military medical academy in Leningrad in the 1930’s?
o Stimulating electrodes inserted into the middle ear of patients with and without ME structures
o Frequency of AC (alternating current) was varied and patients asked to describe the pitch (Fersuni & Volokhov, 1936)
o Pitch was no different for patients with or without ME structures
Define electrophonic hearing.
Electrical stimulation of the Organ of Corti causes mechanical response= release of neurotransmitters from hair cells onto nerve VIII (Stevens & Jones, 1939)
Basiliar membrane moves in response to voltage changes.
How does electrophonic hearing work?
o Tectorial membrane converts electrical signal into acoustic resulting in tonal pitch but at double the signal frequency
o Direct electrical activation of nerve CIII w/ steep loudness growth and occasional activation of nerve VIII
o The more direct electrical stimulation given to nerve VIII results in stimulation of nerve VII
Define the cochlear microphonic.
Electrical potentials measured primarily from OHCs in cochlea in response to stimulus closely mirrored the stimulus (Wever and Brady, 1930)
Why did the cochlear microphonic dismiss the “telephone theory” of hearing?
The stimulus is not passed down site to site to site, with information lost.
The cochlear microphonic closely mirrors the actual stimulus.
What did Gersuni and Volokhov report?
1936
Hearing at different pitches arose from different rates of stimulation in electrical hearing.
What did Homer Dudley crate in 1939?
Vocoder.
Basis for early speech processing strategies for multi-channel implants.
Take signal and modify it in some way to change the outcome at stimulation (not 1-to-1 transmission)
What kind of research was conducted in the 1940’s and 1950’s?
Large amounts of research went into telephonic hearing.
Conclusion= deafness could not be completely corrected with wide-field electrical stimulation. Instead, more localized stimulation of auditory nerve fibers would be necessary.
When was the first CI invented?
1950’s
Surgeon Lundberg directly stimulated auditory nerve in patient during neurosurgery.
He used sinusoidal current and patient reported hearing only noise.
What work was done by Djourno and Eyries in 1957?
Conducted seminal work on direct auditory nerve stimulation with coil.
o First subject was a 57-year-old-man s/p bilateral cholesteatoma resection which resulted in deafness (nerve VIII) and facial paralysis (nerve VII). Surgery performed on 2/25/1957
o Patient underwent extensive therapy and was able to discriminate intensity differences well. Frequency perception was poor and speech perception non-existent
Low frequencies: burlap tearing
High frequencies: silk ripping
o Could appreciate environmental noises and single words, but could not understand speech
o Implant subsequently malfunctioned (twice) and Eyries and Djourno stopped working together
Describe the CI created by William House, M. D., D. D. S.
- First patients implanted in January 1961 had a gold wire implanted through the round window and brought out through the skin
- All three attempts (2 patients) yielded patient perception of square-wave stimulus, but all three had to be removed secondary to biocompatibility concerns
- Required current for stimulus perception increased over the course of use for both patients
Describe the CI created by F. Blair Simmons.
• Conducted intraoperative study in an 18 y/o patient, which indicated bipolar stimulation of a nerve VIII yielded auditory sensations and discrimination of different stimulus frequencies
• Two years later (1964), he implanted an electrical hearing device into the modiolus of a 60-year-old-man
• Follow-up psychophysical testing of the patient was difficult and Simmons was pessimistic about future electrical stimulation of nerve VIII yielding useful speech information
o Use of electrical hearing for communication was “less than 5%” likely and Stanford put off human experimentation until animal testing could be done
o Currently, modiolus is the target for CIs
When was the multi-channel CI proposed?
Robin Michelson, M.D., had implanted several deaf patients with single-channel cochlear implants in 1960’s
- Found that patients could discriminate among different stimulation rates up to 600 Hz and differentiate between square and sinusoid wave
- Showed that IC neurons responded similarly in animals with destroyed hair cells and those with intact hair cells
- First proof that electrical hearing was stimulating auditory nerve and not electrophonic hearing
- Also demonstrated that in single electrode devices, periodicity pitch up to 600 Hz possible, but place coding impossible
- In order to convey speech signal, would need multi-channel implant
- Presented findings at American Otologic Society in 1973
What is the Bilger report?
1975: 13 single-channel CI users (11 by House and 2 by Michelson) were studied in Pittsburgh
o Audiologic
o Vestibular
o Psychoacoustic
• First study that legitimized CI use
• Found that speech-reading scores were improved in all adults and that quality of life was significantly improved with minimal risk
o Still no open set speech recognition
o Voice production improved
What is the House/3M device?
1972: House and Urban developed speech processor to accompany their single-channel device (3M)
• First on-market device
• Implanted approximately 1000 people with device between 1972 and 1980’s
• Age criteria lowered from 18 years to 2 years of age in 1980
• Received FDA approval for commercial marketing device in 1984
When was the multi-channel CI created?
Late 1970s and early 1980s by Michelson and Graham Clark
- Improve safety and durability of electrode array
- Ultimately led to production of Clarion (AB) and Nucleus (Cochlear) devices currently on market
When was MED-EL founded and when was it approved by the FDA?
“First developed” in 1875
Approved by FDA in 2001
When was AB founded and when was it approved by the FDA?
Founded in 1993
Approved by FDA in 1996
What is incidence?
Occurrence rate
