MEI Midterm Flashcards
What are the FDA-approved indications for middle ear implants
- 18 years & older w/ SNHL.
- Moderate to moderately severe SNHL w/ WRS greater than >60% correct.
- Normal middle ear anatomy and function without an infection.
- Prior experience with hearing aids.
- Off-label recommendations for middle ear implants may be made when medically justified, regardless of FDA-approved indications.
What does it mean if at middle ear implant patient has a WRS score of less than 60%?
- Individuals with WRS <60% correct in optimal conditions may not experience significant improvement in hearing performance with a middle ear implant.
how is candidacy assessed for middle ear implant?
Preop Assessment
* Air and bone conduction pure-tone @ 250 hz - 8,000hz (octave and inter-octave frequencies) ( no ABG more than 10db)
* Check middle ear function w/ tymps, ARTs, wideband reflectance
* HA’s trial (conventional air-conduction hearing aids).
* REM measurements to ensure optimal hearing aid output. (during trial or to make sure use of was optimal)
* Aided WRS at speech levels of daily listening (60 dB SPL)
* Medical evaluation by an otologist & CT check ME anatomy & surgical planning
* MRI to assess the central nervous system.
What are the theoretical advantages of middle ear implants, and which of these remain applicable today? (bolded are still true today)
Greater Gain: increased gain prior to acoustic feedback. but feedback risk remains due to enhanced mechanical oscillation.
Avoidance of the Occlusion Effect: crucial for individuals with external otitis or skin allergies. unaffected by cerumen-related problems.
Improved Comfort: especially with fully implanted
Higher-Fidelity Sound: higher-fidelity sound w/less distortion.
Aesthetic Appeal: especially if components are implanted under the skin. (today)
Continuous Wear: Fully implantable allow 24/7 wear, including showering and sleeping, with minimal acoustic feedback risk. (today)
What are the theoretical disadvantages of middle ear implants?
- Surgical Procedure: Requires 1-2 hours under general anesthesia, w/ facial nerve injury and infection risk. Complication rates are generally low, but healing time is needed before activation.
- Cost and Insurance: Higher costs, not typically covered by insurance. PT’s out-of-pocket expenses for AuD services.
- Hearing Implications: Some MEI involve disarticulation of ossicular chain, resulting in maximum conductive hearing loss when inactive.
- Not MRI Compatibile: Most MEI contain magnets, prohibiting MRI without implant removal. Exception: MED-EL VIBRANT SOUNDBRIDGE allows MRI up to 1.5-tesla without removal.
- Verification Challenges: REM unfeasible for verifying gain/output settings. b/c MEI don’t produce acoustic output in the ear canal, making traditional
What MEI is MRI compatible and up to what TESLA?
MED-EL VIBRANT SOUNDBRIDGE allows MRI up to 1.5-tesla without removal.
What are the three types of transducers used in middle ear implants?
Piezoelectric
Electromagnetic
Electromechanical
Crystals Ocillate when electicity is applied and ossiclation enegerate electrical volatge, convereted to mechanical energy, when attech to ME moves ossicles converting Mechnical Energy to electrical signal for processing
Piezoelectric
Pros and Cons of the Piezoelectric transducers
Pros
* No external power needed
* strong stability and durable.
Cons
* not enough amplification formoderate to severe hearing loss due to their limited output and narrow bandwidth
A magnet is attached to the ossicles. A wired coil is placed nearby. When electrical current flows through coil it creates a changing magnetic field. This MF causes the magnet to vibrate (oscillate back & forth). Magnet Oscillation sends mechanical energy to ossicaular chain.
* Magnet movement Intensity and frequency is equal to the electrical current’s characteristics.
Electromagnetic
Pros and cons of the Electromagnetic transducer
Pros: None?
Cons:
* output is dependent on the magnet to coil distance
* increased distance = decreased output.
A magnet & coil is attached to the ossicles (housed together). When electrical current flows through coil it creates a changing magnetic field. This Magnetic Field causes the magnet to vibrate (oscillate back & forth). Magnet Oscillation sends mechanical energy to ossicular chain.
Electromechanical
Pros and Cons of the Electromechanical transducer.
Pros:
* highest output and widest frequency responses
* Not affected by variable output due to changes in magnet to coil distance. (housed together)
Cons:
* More complex design and more prone to mechanical failure. Small drawback now with modern tech
What middle ear implant devices are currently available?
Partially Implantable
* Vibrant Soundbridge
* MAXUM
Fully Implantable
* Envoy Esteem
Label 1-4 on the Vibrant Soundbridge
- A receiving coil that surrounds a biocompatible magnet
- An internal processor and stimulator (i.e., the “demodulator”)
- A lead (the Conductor Link) that delivers electrical current from the stimulator to the transducer
- Floating Mass Transducer (FMT)
Vibrant Soundbridge
* implant type
* Basic components
* Transducer type
* How does it work
MED-EL Vibrant Soundbridge
* Partially implantable MEI
* Two basic: External sound processor (SAMBA 2 audio processor & the MED-EL Vibrant Soundbridge Implant
* Electromagnetic Transducer
* Microphone capures sound –> analyzed by digital signal processor–> converted to electrical –> transmitted via electromagnetic to–> processor transmitting coil –> coil recieves and converts to electrical signal –> to implant processor for analysis –> eletrical current down the conductor link –> to FMT (electromechanical) –> coil creats mag field and magnet ossilate wi/FNT
FDA-approved indications for use of the MED-EL VIBRANT SOUNDBRIDGE
- 18 or older
- SNHL
- Moderate to severe (Mild @ 500 hz)
- WRS ≥ 50% correct @65dBSPL
- norm ME anatomy
- Realistic expectations of the benefits and limitations of the device.
MED-EL VIBRANT SOUNDBRIDGE contain what 2 basic componens?
Partially Implantable MEI
* An external sound processor known as SAMBA 2 audio processor
* The MED-EL VIBRANT SOUNDBRIDGE implant
The FMT on the MED-EL vibrant soundbridge is coupled to what?
FMT coupled to the long process of the incus
* rarely couple to the incus body
* for mixed/condutive HL - coupled to round window
How does the MED-EL VIBRANT SOUNDBRIDGE work?
- Sound is pick up by the microphones on the sound Processor and analyzed by the digital signal processor
- Signal is converted to electrical current and transmitted though the processor transmitted coil
- coil recives and converts to electrical signal & delivered to implant
- Analysised by implant
- travels down conductor link lead to FMT
- FMT is magnet and col to create magnetic field (electromagnetic)
Sound picked up –> analyzed –> converted to electric –> transmitted through coil–> coil converts to electrocal signal–> delivers to implant —> analysied –> travel down conductor link lead –.> to FMT–>
Vibrant sondbridge contraindications
- CHL
- Retrocohlear or Cental Auditory disorder
- Tympanic membrane perforation associated w/ME infection
- A skin or scalp condition
The MAXUM contain what two components?
Ear Level Sound Processor aka Integrated Processor & Coil (IPC)
* Micorphone
* Digital SIgnal Processor
* Eletroomagnetic coil
Magnet (house in titanium)
* attached to ossicles
How does the MAXUM work?
- IPC (Integrated Processor & Coil) houses both sound processor & eletromagtic coil
- IPC receives sound, amplifies it and convert to electrical current
- delivered to electromagnetic coil
- as E current travel throough coil it’s converted to electromagnetic signal
- EM signal moves across the TM and towards MAXUM Magnet
- Magnet coupled to neck of stapes
- engages in electromagtic virbations and process
MAXUM FDA approved indications
- 18+
- Moderate to Severe SNHL
- prior HA’s (REM fit)
- no ABG ^10db
- WRS ≥ 60db
