ABA Cochlear Implants & Implantable Hearing Devices 1 — Questions and Answers
Question 1: Which structure in the cochlea is the target for cochlear implant electrode array insertion?
- Scala vestibuli
- Scala media
- Scala tympani (Correct answer)
- Organ of Corti
Correct answer: Scala tympani
The electrode array is inserted into the scala tympani because it is more accessible via the round window or cochleostomy and is closest to the spiral ganglion neurons.
Question 2: What is the minimum unaided pure-tone average (PTA) criterion typically used for adult cochlear implant candidacy in the better-hearing ear?
- 25 dB HL
- 40 dB HL
- 70 dB HL (Correct answer)
- 90 dB HL
Correct answer: 70 dB HL
Current FDA guidelines and most centers require a PTA of 70 dB HL or greater in the better ear as part of adult cochlear implant candidacy.
Question 3: Which speech recognition score threshold is commonly used as part of adult CI candidacy evaluation?
- Less than 20% on aided CNC word recognition
- Less than 40% on aided CNC word recognition
- Less than 60% on aided CNC word recognition (Correct answer)
- Less than 80% on aided CNC word recognition
Correct answer: Less than 60% on aided CNC word recognition
Adults scoring less than 60% on aided CNC monosyllabic word recognition tests in the best-aided condition typically meet speech perception criteria for CI candidacy.
Question 4: What does the term 'neural response telemetry' (NRT) or 'neural response imaging' (NRI) measure during cochlear implant programming?
- The impedance of each electrode contact
- The electrically evoked compound action potential of the auditory nerve (Correct answer)
- The acoustic stapedial reflex threshold
- The cortical auditory evoked potential
Correct answer: The electrically evoked compound action potential of the auditory nerve
NRT/NRI measures the electrically evoked compound action potential (ECAP) of the auditory nerve, providing objective data to guide initial CI programming.
Question 5: In cochlear implant programming, what does 'T-level' (threshold level) refer to?
- The loudest comfortable level of electrical stimulation
- The minimum level of electrical stimulation that produces a just-audible percept (Correct answer)
- The level at which acoustic tinnitus is masked
- The impedance threshold for an electrode channel
Correct answer: The minimum level of electrical stimulation that produces a just-audible percept
The T-level is the minimum electrical stimulation level at which the CI recipient just barely perceives sound, analogous to a threshold in behavioral audiometry.
Question 6: Which condition is considered a contraindication to cochlear implantation?
- Bilateral severe-to-profound SNHL
- Absent or severely deficient auditory nerve (cochlear nerve aplasia) (Correct answer)
- Age over 70 years
- History of otitis media
Correct answer: Absent or severely deficient auditory nerve (cochlear nerve aplasia)
Cochlear nerve aplasia or severe deficiency renders a cochlear implant ineffective because there are insufficient auditory nerve fibers to transmit the electrical signal to the brain.
Question 7: What is the primary advantage of a 'bimodal' fitting for a cochlear implant recipient?
- Reduces the need for auditory rehabilitation
- Uses two cochlear implants simultaneously for better localization
- Combines a CI in one ear with a hearing aid in the opposite ear to improve speech perception, especially in noise (Correct answer)
- Provides bilateral electrical stimulation using a single internal device
Correct answer: Combines a CI in one ear with a hearing aid in the opposite ear to improve speech perception, especially in noise
Bimodal hearing pairs a CI with a conventional hearing aid in the contralateral ear, leveraging residual acoustic hearing to improve speech understanding in noise and music perception.
ABA Cochlear Implants & Implantable Hearing Devices 1
Which structure in the cochlea is the target for cochlear implant electrode array insertion?