Implantables Midterm Flashcards
What are middle ear implants (MEI)?
surgically implanted component that is coupled to a structure in the ME and that mechanically oscillates to facilitate stimulation of the cochlea
What are the theoretical advantages of MEI?
greater gain, improved comfort, higher fidelity sound, not needing as much gain due to the nature of the implants, aesthetic appeal and good for patients who want continuous wear
What are the theoretical disadvantages of MEI?
surgical procedure, cost is high as insurance does not often cover the devices, hearing implications as a result of disarticulation potentially needing to occur, not MRI compatible beyond 1.5 T and there are troubles with verification as there is no acoustical output to measure within the canal
are patients with conductive HL candidates for MEI?
they were not originally included within the MEI candidacy however some patients may be considered as a candidate if their ME is aerated and free of chronic effusion
-additionally, some implants can be coupled to the round window therefore avoiding the ossicles so could be beneficial for otosclerosis
what assessments do we conduct for potential MEI patients?
-air and bone thresholds at 250 to 8000 Hz
-evaluation of ME function through tymps, reflexes and wideband reflectance
-trial with conventional HAs
-real ear probe microphone measurements to ensure optimal HA output
-aided WRS at levels consistent with daily listening situations (both at 60-65 and 50 dB SPL)
-medical evaluation by an otologist, including a CT scan or even an MRI to assess CNS
what is the audiological management with MEI?
-activation occurs weeks after surgery
-devices are programmed using software given by the manufacturer
-verification relies on behavioral and functional measures (including sound field threshold, aided WRS, Quick-SIN, and questionnaires)
what are the 3 types of transducers that are used with MEI?
piezoelectric, electromagnetic, and electromechanical
what is a piezoelectric transducer, and how does it work?
this transducer possesses a unique property, as when they come in contact with electricity,y they oscillate
-when they are coupled to the ME, the material delivers mechanical energy, converting sound-induced vibrations into electrical signals for processing
-the intensity and frequency generated are proportional to the intensity and frequency of the driving force
what are the advantages of a piezoelectric transducers?
there is no external power source required, and they have relatively robust durability
what are the limitations/disadvantages of a piezoelectric transducers?
may not provide enough amplification due to limited output and a narrow bandwidth
what is an electromagnetic transducer, and how does it work?
this transducer features a biocompatible magnetic coupled to the ossicular chain or ME structure and is positioned near a wired coil within the canal
-as an electrical current goes through the coil, it generates a fluctuating magnetic field, causing the magnet to oscillate and transfer mechanical energy to the ossicular chain
-the magnet moving along with the ossicle,s giving a back-and-forth movement between the magnet/coil
what are the limitations/disadvantages of an electromagnetic transducers?
the output depends on the magnet-coil proximity
-decreasing with longer distance
-with this type of transducer, since the magnet is on the ossicular chain and the wire is in the canal, the fluctuations that occur depend on the proximity
why was the electromechanical transducer designed?
this transducer was designed to eliminate the limitation of distance with electromagnetic transducers
-the coil and magnet are within one unit, ensuring mechanical energy transfer to the coupled structure within the ossicles
what are the advantages of an electromechanical transducers?
delivers higher output levels/wider frequency response and is not impacted by variable output due to changes in magnet coil distance
what are the limitations/disadvantages of an electromechanical transducers?
complex design and is more prone to mechanical failure
what are the three MEI devices offered today?
vibrant sound bridge, maxum (ototronix), envoy esteem
tell me about the vibrant sound bridge MEI
a partially implanted MEI that contains both an external sound processor and the internal soundbridge implant
-sound is captured by the microphone, then is analyzed and converted to an electrical current
-this is then transmitted through electromagnetic induction and is altered back to the electrical signal and once it is received by the FMT the ossicular chain is set into motion
what is the FMT within the vibrant soundbridge?
the floating mass transducer which is attached to the ossicular chain and receives the electrical current
tell me about the maxum (ototronix) MEI?
a partially implanted device with the external integrated processor and the iron magnet
-the IPC is placed within the canal and the magnet is housed somewhere on the ossicles
-when the IPC receives the sound, it becomes amplified and converted to an electrical current
-this current crosses the TM as an electromagnetic signal and goes towards the magnet
-this causes the implant to vibrate, and therefore the ossicles vibrate
tell me about the envoy esteem MEI?
a fully implantable device that has all component combined into one device
-the sensor, containing piezoelectric transducer, converts the movement of the incus to an electrical signal that is delivered to the sound processor
-it then reaches the driver, and is then converted to mechanical oscillations causing the stapes to vibrate
what are the general FDA indications for MEIs?
-18 years +
-SNHL in the moderate to severe range
-WRS greater then 40-60% (depends on manufacturer)
-normal ME anatomy/function
-experience with appropriately fit HAs
-ABGs no larger than 10 dB
what are the general contraindications for MEI?
-conductive HL
-retrocochlear or central auditory disorders
-active or history of recurrent ME infections
-TM perforations
-disabling tinnitus
-any skin or scalp conditions/sensitivities
what are bone conduction hearing devices?
HA that amplifies sound through bone conduction, serving as an alternative to a regular HA for those with problems in their outer or middle ears
what are the basic components of bone conduction devices? what is the job of each?
-external sound processor, captures the signal and converts it to mechanical vibrations, delivering those vibrations to the internal components
-titanium component which is surgically implanted in the skull and uses those mechanical vibrations to the cochlea through bone conduction
-abutment, sits on the fixture holding it into place
bone conduction devices utilize an electromagnetic transducer. What is the main function of this transducer within bone conduction devices?
to convert the electrical current into mechanical energy
what are the two components within the electromagnetic transducer of bone conduction devices?
-armature, surrounded by wire coils and contains a magnet that allows it to move when stimulated
-yoke, remaining fixed and does not move
how does the electromagnetic transducer function within the bone conduction devices?
-when an electrical current is delivered, a magnetic field is generated within the armature
-fluctuations within the current create an oscillating magnetic field, attracting and repelling the armature to and from the yoke
-this causes the mechanical energy within the transducer to be transmitted to the skull
what are the common complications of bone conduction devices?
-peri-implant infection
-flap necrosis
-loss of abutment
-Osseointegration failure
-cosmetic factors
-skin numbness
-skin overgrowth
what is a skin drive bone conduction device?
vibrations are transmitted to the bone through the skin using an external device that is placed on the skin surface
what is a direct drive bone conduction device?
Vibrations are directly transmitted to the bone through an implanted transducer, without the need for skin transmission
what is an active bone conduction implant?
transducer is implanted and the generated vibration is directly applied to the bone
-gives optimum BC sound transmission as it is not attenuated
-transducer is within the implant
what is a passive bone conduction implant?
transducer is within the speech processor and the stimulation is applied from the outside onto the skin
-less optimal as the skin attenuates the signal before it reaches the bone
-transducer is within the speech processor on top of the skin
what is a percutaneous bone conduction device?
the skin is not intact as the implant is penetrating the skin
-titanium fixture is implanted into the skull and protrudes outward
what are the advantages of percutaneous bone conduction device?
-direct transmission resulting in optimal signal delivery
-beneficial for those with skin sensitivity issues (as no pressure(
-excellent retention
-approval for MRI with strength up to 3T
-implant related shadow is minimized
what are the limitations of percutaneous bone conduction device? when can they be activated?
-heightened risk of abutment-related complications such as skin overgrowth
-needs to maintain good hygiene at the abutment
-activation must occur 3-6 months after surgery, according to FDA
-aesthetic concerns
-difficult to handle if dexterity issues are present
-higher risk of loss from trauma
what are the indications for a percutaneous bone conduction device?
-5 years +
-CHL who cannot benefit from conventional HAs
-MHL with mild to moderate SNHL, bone thresholds 65 dB or better
-SSD with the better hearing ear BC of 20 dB or better
what is a transcutaneous bone conduction device?
the skin is intact and the vibrations from the sound processor are transmitted across the skull
-titanium component is coupled to a magnetic plate that rests on top of the skull
what are the advantages of a transcutaneous bone conduction devices? when can they be activated?
-lower rate of complications at and around the incision site
-minimal wound care
-superior aesthetics
-easier attachment and removal
-less risk of trauma to the implant
-can be activated within 4 weeks of surgery
what are the limitations of transcutaneous bone conduction devices?
-vibrations are transmitted across the skin, meaning skin will attenuate the signal
-insufficient power for people with BC thresholds in the mild to moderate HL range
-not cleared for MRI with a strength exceeding 1.5T
-implant’s magnetic plate will create artifact/shadowing in and around the implant area
-magnet pressure may aggravate soft tissue problems
what are the indications for transcutaneous bone conduction devices?
-5 years + with skull thickness of at least 2.5mm and skin thickness of at least 3 mm
-BC thresholds of 45 dB HL or better
-suitable for SSD with normal BC in the better hearing ear
what are osseointegrated bone conduction device?
implant requires surgically placing an implant screw that will integrate with the temporal bone
What are non-osseointegrated bone conduction devices?
implants are attached to the bone of the skull, but does not rely on osseointegration for the function of the device
what is osseointegration?
the process in which bone cells attach/adhere to the surface of a metal titanium surface
-the bone cells adhere to the surface of the fixture
what is the process of osseointegration? stages?
implant screw is surgically placed and eventually will become osseointegrated to the temporal bone
-one stage process occurs when implant and abutment is placed as a single piece
-two stage process occurs when the implant is implanted first then at another date the abutment is placed after osseointegration has taken placed
what is the BCD candidacy for CHL/MHL?
-average BC of less than or equal to 65 dB HL
-average ABG of greater than 30 dB HL (additional consideration and not necessary)
what is the BCD candidacy for SSD?
-poor ear has profound SNHL of greater than or equal to 80 dB HL
-good ear has a PTA of less than 20 dB
what are the benefits of BCDs for those patients with SSD?
alleviated head shadow effect improving speech recognition in quiet and in noise when the speech arrives from the side of the poorer ear
-think of it as a CROS
for any bone conduction devices, what is the age requirement?
-for surgical options 5 years and older
-for nonsurgical options they can be any age
what does the BCD evaluation for CHL/MHL consist of?
-functional gain in soundfield using warble tones
-functional gain CNC words at 65 dB
-functional gain adaptive SIN testing at 65 dBA
what does the BCD evaluation for SSD?
-functional gain in the soundfield using warble tones
-functional gain adaptive SIN testing at 65 dBA
for BCD evaluations, how does the set up differ for CHL/MHL and SSD?
for CHL/MHL: speech in front of patient with noise in the back or side
for SSD: speech on the worse ear side and noise on the better ear side
what are the common BCD?
BAHA connect, BAHA attract, osia, oticon ponto, MED-EL bonebridge, MED-EL ADHEAR, medtronic sophono and nonsurgical options
tell me about the BAHA connect
a percutaneous device that utilizes a TiOblast surface to help facilitate rapid osseointegration
-FDA approved 12 week gap however activation can now occur within 4-6 weeks due to using the TiOblast
tell me about the BAHA attract
a transcutaneous device that utilizes a magnet to attach to the under skin components
tell me about the osia
a transcutaneous device utilizes osteointegration but also uses a piezoelectric transducer that undergoes mechanical deformation
-attenuation from the skin is avoided
tell me about the oticon ponto
a percutaneous device that has enhanced stability and contains all the features of a advanced HA
tell me about the MED-EL bonebridge
an active bone conduction device that uses electromagnetic transducer that is anchored directly to the bone
-transcutaneous device since the skin is intact
tell me about the MED-EL ADHEAR, also what is it’s nickname
a active non surgical device that does not exert pressure on the skin
-known as the stick, click and hear
tell me about the medtronic sophono
a transcutaneous device that contains 2 magnets enclosed within a case and is designed to be implanted within a single procedure
tell me about nonsurgical options
generally will apply steady pressure to the mastoid and can be through an elastic band or eyeglasses
-limited by soft tissue and chronic pressure from the device
who is considered the father of the CI?
william house
what is the bilger report and why is it considered a landmark for CIs?
the bilger’s report was a NIH funded study conducted by dr. robert bilger that evaluated early CIs
-the results were significant as it showed that CIs improved quality of life for all study subjects and as a result it led to the NIH providing more funding for CI research
which FDA center is responsible for overseeing CI devices?
center of devices and radiological health (CDRH)
there are 3 different medical device classes, all ranked based on the amount of risk they have. what device has the least amount of risk? what has the most amount of risk?
class 1 - least amount of risk
class 3 - most amount of risk
what class of medical devices are cochlear implants?
class 3
what is premarket approval (PMA)?
this is required before any marketing and/or distribution occurs with class 2 and 3 devices
-scientific review by FDA staff
-regulatory and quality system review by FDA personnel
-review/recommendation by appropriate advisory committee
-final deliberations, documentation and notification of the FDA decision
what are some examples of changes that require a PMA supplement?
new indication for usage of the device, labeling changes, using a different facility, changes in packaging
who is responsible for designating indications for CIs?
the manufacturers submit a PMA application outlining indications for their device and the FDAs role is to approve or reject the application
what are the labeled and off label indications?
labeled : manufacturer defined indications listed on the package insert
off label : provisions of a CI to a patient who does not meet the approved indications
what is the traditional CI candidacy for adult candidates? (Advanced Bionics, Cochlear Americas, and MED-EL devices)
-18 years +
-moderate to profound bilateral SNHL, low frequencies being more moderate and highs being more profound
-limited benefit from amplification (50% or worse in ear to implanted, 60% in the other ear)
what is the traditional CI candidacy for children?(Advanced Bionics, Cochlear Americas, and MED-EL devices)
-bilateral profound SNHL or severe to profound SNHL (2+)
-little or no benefit from appropriately fitted HAs observed through a 3 to 6 month trial period
what is the non-traditional CI candidacy for adult candidates? (Cochlear Hybrid, MED-EL EAS systems, SSD, and AHL)
18+
normal to moderate LF HL
severe to profound HF
when is unilateral CI implantation considered?
when one ear is profound and the other is normal
According to MSTB-3, what are the four key steps in the cochlear implant candidacy assessment process recommended for best clinical practice?
- comprehensive audiologic eval
- hearing aid verification
- aided speech recognition
- outcome measures (patient questionnaires)
What is the purpose of a hearing aid evaluation prior to beginning aided speech assessment?
making sure the hearing aids are working at optimal level so testing is accurate
What is the purpose of calibration prior to aided speech assessment?
making sure we are testing at the right loudness so the results are accurate. if we are testing to low and want to see how they do aided and the stimulus us quiet the results wont be as good as we expect
What are the main speech tests used in the MSTB-3 battery?
AzBio & CNC words
How is ANSD diagnosed in children, and why is additional testing important for determining the site of lesion?
How its diagnoses = tests, present oae’s, reflexes, ABR presence of cochlear microphonic
additional testing tells us whether the site of lesion is cochlear or neutral , crucial for determining candidacy and prognosis
what is the CI candidacy for SSD/AHL?
-5 years +
-unilateral severe to profound SNHL in the poor ear and either normal or mild to moderate SNHL in the better ear
-limited benefit from hearing devices with a score of less than 5% on CNC
what is the medicare eligibility criteria for CI coverage?
-diagnosis of bilateral moderate to profound SNHL with limited benefit from appropriate HAs or vibrotactile aids
-free from ME infection, accessible cochlear lumen that is suited for implantation and free from lesions within the auditory nerve or acoustic areas of CNS
-no contraindications for surgery
-device must be used with label reasonings
typically CIs patients need to show some sort of HA trial period, however under what circumstances would this be waved for children?
in cases of meningitis
-due to bone build up, there can be ossification of the cochlea so implantation should occur as soon as possible to avoid that from occurring
what is the minimum and maximum age approved by the FDA for CIs?
9 months, with no maximum age
why is it important to image the auditory anatomy with CT and/or MRI prior to implantation?
-determines possibility of inserting an electrode into the cochlea
-confirms if the auditory nerve is present and/or normal
-identified which (if any) ear may be more suitable
what are the contraindications for CIs?
-absent cochlea/cochlear nerve
-neurological damage impeding auditory processing
-damaged auditory cortex
-medical conditions preventing surgery
-any medical risks of surgery that exceed the expected benefits
what are some factors that are used to determine which ear should be implanted, if both qualify?
-anatomy aspects
-typically worse hearing ear will be implanted
-patients hand preference
-occupation
-if facial nerve is too close to the cochlea
-if there is no difference, then the right may be selected (as speech and hearing centers are on the left side)
what are some factors that affect CI outcomes in adults and briefly how do they impact it?
-simple variation in performance
-duration of HL as most studies have found that longer duration of deafness has negative impacts of CI performance
-age of implantation, as studies have shown younger tends to have better outcomes
-preoperative hearing status, all dependent on the amount of cochlea or nerve damage
-etiology, those with sudden HL may perform better and those with ANSD or a temporal bone fracture may perform poorer
what are some factors that affect CI outcomes in pediatrics and briefly how do they impact it?
-simple variation in performance
-age of identification/intervention/implantation, as better outcomes have been associated with those who received it at earlier ages
-mode of communication, as those who rely more solely on auditory input have shown better outcomes
-etiology, not necessarily impacting the implant but the post implant success
-preoperative hearing status, as some studies have shown that children with residual hearing have shown better outcomes
what are the 60/60 guidelines for cochlear implants?
best ear unaided monosyllabic word score is less than or equal to 60% correct and an unaided PTA in their better ear greater than or equal to 60 dB HL
-calls to look at the audio to identify the PTA and WRS
-if either ear meets this, refer for a CIE
what testing protocol do we use for CIE?
MSTB-3
tell me about the comprehensive audiological evaluation for CI candidacy testing
otoscopy, immittance and thresholds
-including 125 as it helps assess hearing preservation, determines post operative amplification and helps support counseling
tell me about hearing aid verification for CI candidacy testing
needing to ensure that the patients HAs are verified to optimize to the maximum HA benefit
tell me about aided speech recognition testing for CI candidacy testing
testing both CNC and AzBio within the soundfield
-patient should be 1 meter from speaker at 0 degrees azimuth
-with SSD/AHL the signal to worse ear, noise to the better ear
what are the cutoff scores for CNC tests?
will vary from clinic to clinic but generally it will range from 40-60%
-so rule of thumb, generally not performing any better than 60%
previously with the MSTB protocols, AzBio was the main determinant for CI candidacy however within MSTB-3 CNC is the main test for determining candidacy. what are the rationales for this change?
CNC is a more true test of hearing as if you hear a word you hear it but if you don’t then it will often be wrong BUT with sentences you have context cues to fill in gaps
-additionally CNC is less likely to have the ceiling effect as well as truly testing hearing and not any cognitive skills
what is the CI testing protocol for traditional candidates?
best aided individual ear CNC scores at 60 dBA (needing to test individually)
-if they are a candidate then continue to test AzBio at a +10 dB SNR, +5 dB SNR then an everyday listening situation
-if they are not a candidate from the CNC scores, testing is done
-continue with outcome measures
-continue with medical evaluation
what is the CI testing protocol for SSD/AHL?
best aided individual ear CNC in the ear to be implanted at 60 dBA
-if they are a candidate then continue to test the AzBio at 0 dB SNR and then at everyday listening condition
-if they are not a candidate from the CNC score, testing is done
-continue with outcome measures
-continue with medical evaluation
why is it important to isolate the NTE during CI candidacy testing
we can be sure that the information we are gaining is relative to that ear alone
-any residual hearing in the NTW can make the results not accurate for the ear of interest
tell me about CI candidacy testing, outcome measures
questionnaires be administered in conjunction with speech recognition testing to give additional information regarding the patients overall hearing performance
-can include the CIQOL-10 and the SSQ-12
what are 3 common approaches to isolate the NTE
(1) plug and muff (2) masking noise through an insert that is between 50 and 80 (3) insert phone with a circumaural headphone creating an acoustic seal
what is the main purpose of the postoperative outcome assessment?
to ensure a patients amplification is appropriate and that the amplification is maximizing his/her auditory potential
tell me about MSTB-3 protocol for postoperative outcome assessments
-unaided thresholds in both ears for AC and BC
-aided SF threshold for implanted ears
-aided speech assessment
-questionnaires to evaluate benefit
what is the recommended schedule for follows up post implantation
testing recommended at 3 months and 12 months following implantation
-if performance is suboptimal at 3 months, consider additional testing before 12 months
how are benefits of bimodal hearing determined
compare performance on AzBio at +10 dB SNR using the CI alone and then the CI + HA
-there should be an improvement indicating a bimodal benefit
examples of parental questionnaires
IT-MAIS (for youngers) and MAIS (for older) and PEACH (up to 7)
external sound components of the CI
microphone, digital sound processor, coil/antenna, magnet and power source
internal implant of the CI components
magnet, receiving/transmitting coil, digital sound processor, stimulator for electric pulse generator, electrode leads and electrode arrays
in general, how does a CI convert sound into electrical stimulation
-microphone picks up sound, amplifies it and converts it to an electrical signal
-electrical signal goes to speech processor
-processor converts the signal to digital information
-this then gets sent to the transmitting coil which transmits both this signal and power to the internal receiver
-the receiver decodes the signal and delivers electrical stimulation pulses to the electrode array that is within the cochlea
-the electrodes stimulate the auditory nerve terminals using current pulses
how does the electromagentic transducer convert sound into mechanical energy
through oscillating magnetic fields that move an armature to create vibration
what is a key distinction between percutaneous and transcutaneous BCDs in terms of sound transmission
transcutaneous transmits sound vibrations across intact skin
according to FDA guidelines, which type and degree of hearing loss qualifies for a MEI
moderate to moderately severe SNHL
which of the following about the BAHA connect is true
it uses a TiOblast TM surface to enhance osteoblast migration
which audiometric measure is most critical when selecting the appropriate power level of a BC sound processor
bone conduction pure tones
which BCD uses a piezoelectric transducer for mechanical sound generation
cochlear osia
what is an example of a non surgical bone conduction device
MED-EL ADHEAR
in implantable and non surgical BCDs, what is the name of the component that attaches the sound processor to an abutment, magnet or soft band
snap coupling
what is the primary benefit of bone anchored implants for those with SSD
reduction of the head shadow effect, improving speech recognition when sound comes from the poorer ear
the vibrant sound bridge floating mass transducer (FMT) is typically coupled to the …
long process of the incus
what is the primary difference between active and passive bone conduction implants
active devices have an implanted transducer that generates vibration directly to the bone
how is the magnet in the MAXUM system activated to vibrate the ossicular chain
by electromagnetic signals from an in canal processor coil
in the envoy esteem MEI, which component is surgically coupled to the incus
sensor
which MEI is fully implantable
envoy esteem
