oto hearing aids and implantable hearing devices Flashcards
What are assistive listening devices?
Auditory and nonauditory technologies that overcome
limitations associated with the physical distance between
the sound source and the patient
Provide examples of auditory and nonauditory
assistive listening devices.
● Auditory: Microphone systems that capture the desired
sound next to the sound source and transport the signal
to the listener using FM, infrared, induction loop, Blue-
tooth, or hard-wired systems
● Nonauditory: Alarm systems using vibrotactlile or visual
signals to alert the patient of an event such as a phone
ringing or doorbell activation
What conservative measures should be discussed
with patients who have hearing impairment?
Strategic seating at meetings or events (better ear toward
speaker, sitting close to the front), making eye contact with
speakers, reducing competing background noise
Describe the basic components of a hearing aid.
Microphone, amplifier, receiver, power supply
Define gain as it pertains to conventional hearing
aids.
Gain is the difference between the level of input and level of
output at any given frequency.
What advantages do vented hearing aids provide?
Decrease in external auditory canal moisture, decrease in occlusion effect, dissipation of low frequency input (advantageous in patients with primarily high-frequency hearing loss).
What factors should be considered in predicting
patient satisfaction with traditional hearing aids?
The best candidates are motivated patients who are
receptive to the idea of hearing aid use. Those with
predominantly high-frequency hearing loss generally do
better than those with low-frequency hearing loss. Severe
to profound hearing loss is often difficult to aid. Supra-
threshold speech and speech recognition performance is
important; patients with good word recognition when
amplification is provided are more likely to report satisfac-
tion and continued device use.
Describe the difference between the speech
reception threshold and the speech discrimination
score.
Speech reception threshold is the quietest volume (in dB) at
which presented spondaic words can be identified at least
50% of the time, whereas the speech discrimination score is
the percentage of time that a presented word is correctly
identified.
Describe the advantages and disadvantages of the completely-in-canal and the in-the-canal hearing
aid.
● Advantages: Discreet size offering enhanced cosmesis;
takes advantage of the ear’s innate shape assisting with
natural sound amplification and limiting undesirable wind
noise
● Disadvantages: Power limitations, cerumen clogging,
aural fullness and occlusion effect, difficult fit, fine
dexterity requirements, cost, and external ear canal
irritation
Describe the advantages and disadvantages of the in-the-ear hearing aid.
● Advantages: Delivers adequate power to rehabilitate mild
to moderately severe losses, more powerful, and easier to
manipulate than in-the-canal models
● Disadvantages: Require some manual dexterity for place-
ment and volume control. Less discreet than in-the-canal
models
Describe the advantages and disadvantages of the behind-the-ear hearing aid.
● Advantages: Most adaptable hearing aid option; delivers
enough power to rehabilitate moderately severe to severe hearing loss; generally offers more signal processing features; and is easier to handle than smaller
devices in patients with poor manual dexterity
● Disadvantages: Larger size, less discreet, pinna irritation
What is the primary advantage of a body aid?
With severe-to-profound hearing loss, feedback problems
occur with ear-level devices because of the close proximity
of the microphone to the receiver. The body aid places the
microphone at a distant site from the amplifier, typically on
a belt or in a pocket.
With regard to hearing aid technologies, what are
the primary advantages of digital processing
compared with analogue processing?
Beyond affording multiple programs, digital signal processors can selectively amplify specified frequencies, reduce acoustic feedback and background noise, automatically
detect changes in listening environments to dynamically
optimize signal, and offer enhanced connectivity to external
sound sources.
What are directional microphones, and what advantages do they have over standard omnidirectional technologies?
Directional microphones selectively amplify sounds located
in front of the listener, improving the signal-to-noise ratio.
Adaptive directional microphones go one step further and
are able to vary the direction of maximal amplification.
Describe the utility of a CROS and BiCROS aid.
The CROS (contralateral routing of signal) aid takes sound
from the poorer ear and relays the signal to the better,
contralateral ear. The BiCROS (bilateral contralateral routing
of signal) aid similarly “throws” sound to the good ear but
also amplifies sound in the receiving ear.
Which patients are candidates for bone-anchored
hearing aid placement?
Currently, bone-anchored hearing aids are approved for children 5 years of age or older, patients with conductive or
mixed hearing loss who can derive benefit from sound
amplification, and patients with single-sided deafness and
normal hearing in the contralateral ear.
What cells are directly stimulated by cochlear
implant electrodes?
Spiral ganglion cells, found in the modiolus of the cochlea
If facial nerve stimulation occurs with cochlear
implant use, how should this be managed?
The offending electrodes can be selectively deactivated or
removed from the patient’s programming strategy.
What are the Food and Drug Administration
(FDA)’s audiometric candidacy criteria for cochlear
implantation?
Severe to profound SNHL (> 70 dB PTA), with < 50% sen-
tence testing in the ear to be implanted, and < 60% in the contralateral ear or best aided condition
List absolute contraindications to cochlear implantation.
Absent cochlea, congenitally absent cochlear nerve, deaf-
ness secondary to brainstem lesion, previously resected
cochlear nerve
Describe clinical variables that are associated with
good cochlear implant performance.
Age at implantation, prelingual versus postlingual deafness,
duration of deafness, preimplant auditory performance,
duration of cochlear implant use
What is the most common indication for revision
cochlear implant surgery (reimplantation)?
Documented internal device failure
What conditions are associated with an unusually
high prevalence of nonauditory stimulation (pain,
vertigo, facial nerve activation) with cochlear
implant use?
● Otosclerosis: Otic capsule bone is replaced with less dense
otospongiotic bone, which may permit aberrant stimulation pathways, resulting in a higher prevalence of facial nerve stimulation.
● Temporal bone fracture: Similarly, previous temporal bone
fractures may allow abnormal electrical stimulation,
frequently associated with pain.
Describe the benefits of bilateral cochlear implantation.
Improved speech understanding in noise and directional
awareness, as well as the assurance that the “best
performing ear” has been implanted
Theoretically, what is the ideal position of the
cochlear implant electrode within the cochlea?
Perimodiolar within the scala tympani
Describe the potential advantages of implantable
middle ear hearing aids.
Enhanced cosmesis, comfort, discrimination, minimized
feedback, elimination of occlusion effect, permits amplifi-
cation during bathing or swimming
Review the candidacy criteria for implantable
middle ear hearing devices.
Candidates should be ≥ 18 years old, have moderate to
severe SNHL, and have trialed conventional amplification before implantation. Pediatric patients, those with recur-
rent or chronic middle ear disease, patients with poor word discrimination, and subjects with fluctuating loss should not
undergo implantation.
What is the mechanism behind implantable
middle ear hearing aids?
They use either piezoelectric or electromagnetic platforms
that transform sound signal into mechanical energy that is directly coupled to the ossicular chain.
Review the primary implant criteria for auditory
brainstem implantation in the United States.
Bilateral eighth nerve schwannomas (neurofibromatosis
type 2, or NF-2), age ≥ 12 years
What is the typical outcome with auditory
brainstem implantation in patients with NF-2?
Most patients receive limited sound perception that augments lip reading. Few patients experience open-set speech understanding.
