Lecture 3- Alternatives to Traditional Hearing aids Flashcards
Why doesn’t a traditional hearing aid work for everyone?
Some patients reject hearing aids due to their limitations:
- acoustic feedback, occlusion effect, frequent battery changes/maintenance, discomfort, infection, irritation, lifestyle restrictions, repair, loss, and damage
What is the CROS and BiCROS?
- Microphone on bad ear and receiver on better ear
- Solves the head shadow effect problem
- Doesn’t improve localization; some patients report that they can lateralize better
- Can improve spatial awareness
- Do not occlude the good ear
What are the advantages and disadvantages of the Cros/BiCros system?
Advantages: might be covered by insurance, non-invasive, reversible
Disadvantages: might not be covered by insurance, requires 2 devices
What are the candidacy factors for Cochlear Baha?
3 candidate groups: single-sided deafness, mixed hearing loss, conductive hearing loss
3 models: standard, power, and super power
Recommended BC PTA for each model: 45, 55, 65
3 considerations for selection: no pinna or ear canal, lifestyle, gain requirements
What is osseointegration?
Direct connection between bone and implant
What are factors affecting osseointegration?
Material used: implant is made of titanium (99.75%)
Bone condition factors
Surgical considerations:
- bone cannot get too hot
- risk of fibrous tissue growth around the implant
- if the implant is not perpendicular to the skull, it is possible for the implant to make contact with soft tissue
What is the Oticon Ponto?
- Another bone-anchored hearing aid
- Use Oticon’s signal processing
What is the TransEar?
- A single unit
- Behind-the-ear processor has a microphone and an amplifier
- Not very comfortable (transfer unit has to be tight to have bone conduction stimulation)
How does the TransEar work?
- Picks up the acoustic signal and converts to digital
- Digital signal is converted to mechanical energy
- Good ear processes vibrations
What is the Sound Bite?
- Retainer unit that is fit onto the back-teeth of the good-ear side
- Piece behind the ear transfers the acoustic signal to the ITM (in the mouth piece)
- Battery only lasts for 9 hours
How would you counsel your patient with SSD?
- Discuss non-surgical vs. surgical options
- Counsel on the trial period for the CROS system
- Discuss what options are covered by insurance
What is the Lyric?
- Analog hearing aid
- Good for natural sound quality
- Lyric is so deep in the ear; don’t need directional microphone
- Trial period
- Battery lasts up to 120 days (4 months)
- FDA has cleared for 120 days of continuous use
What are the disadvantages of the Lyric system?
- Doesn’t fit every ear
- Can’t fit people who are prone to bleeding, radiation to the head or neck, auto-immune compromised patient
- Price: $2000 per ear per year
- Can’t swim or dive with lyrics; can’t wear during MRI
- Not much published research about Lyric
Who is a candidate for Middle Ear Implants?
- People who do not benefit from or are unable to use traditional hearing aids
- Obstruction of the outer or middle ear
- People who cannot wear hearing aids or ear molds
- People who are unable to benefit from sound amplification
Ex. Physicians who wear stethoscopes, lifeguards, musicians
How might IMEDHDs be better than traditional hearing aids?
- Direct vibrational drive
- 1 less step in transducing sound (reduction in distortion) - Minimal distortion
- Small speaker element - No feedback
- No need for an ear mold; depends on the type of middle ear implant - Special fitting
- Problematic anatomies, conductive hearing loss - Increased long-term wear and comfort
- Improvement in signal processing & noise management (theoretically)
- Good alternative for some patients
What do proponents of Middle Ear implants claim?
- Devices address feedback, occlusion, distortion
- Preserve residual hearing
- Present minimal risk
- Cost-effective over the life of the device
- Permit patients a full range of normal activities (swimming & showering)
- Improve patient quality of life
What is the piezoelectric transducer?
- Based on a ceramic material that will change shape (deform) when a voltage is applied to it
- Wide frequency response
What are the 2 configurations of the piezoelectric transducer?
- Monomorph
- Uses expansion and contraction to directly provide displacement to the middle and inner ear - Bimorph
- Uses 2 pieces of piezoelectric materials bonded together with opposite polarities causing bending of the structures
What are the limitations o the piezoelectric transducer?
- Gain is lower than other devices
- Adequacy of high frequency response is questionable
- Necessity to disarticulate the ossicles is controversial
What is the electromagnetic transducer?
Consist of a magnet (usually made of rare earth, like Samarian cobalt or neudymium iron boron) and an energizing coil
- Becoming a Floating Mass Transducer (FMT) along with a vibrating ossicular prosthesis
- Magnet can be attached to an assicle, the TM, or the oval window
- A fluctuating magnetic field is generated when the coil is energized by a signal corresponding to an acoustic input
- Magnetic field causes the ossicles or the cochlear fluids directly
All components must be in close and stable proximity in order to achieve an efficient system
What are the limitations of the electromagnetic transducer?
- Magnet and the coil must be close together to maximize efficiency
- Magnet weight has to be kept low to avoid mass effect
- Different patients get different results depending on their anatomy
What is the electromechanical transducer?
- Developed in response to limitations of other devices
- Variation of electromagnetic transducer
- Energizing coil and magnet are housed within a single assembly with an optimized spatial and geometric relationship
- Mechanical energy produced is transmitted by a direct connection of the transducer to the ossicular chain - Microphones
- Can be externally worn (like traditional hearing aids), partially implanted
- Could be subcutaneous in the scalp or in the ear canal
What devices are commercially available?
- Vibrant Soundbridget
- Maxum (Ototronix, LLC)
- Carina (Cochlear Americas)
- Esteem (Envoy Medical)
What is the Vibrant Soundbridge?
- One of the first to be FDA approved
- Partially implantable
- Electromagnetic transducer
- Originally developed by Symphonix and then acquired by Med El
Internal part: includes internal receiver coil & magnet
- Wire attached to the long arm of the incus
- Transducer is a magnet surrounded by an electromagnetic coil (FMT) which drives the ossicular chain
External device
- Microphone, signal processor, and magnet
- Amplified sound is transmitted to internal receiver and delivered via the wire to a transducer delivering amplified vibration to the ossicular chain
- Surgery is similar to CI surgery
- Battery changes are about once a week