Physiological Testing Flashcards
Physiological Testing …
- Does not require a voluntary response from the patient
- Can help pinpoint the sit of dysfunction (“site of lesion”)
- Used as cross checkers
- particularly useful for infants and those with disabilities
Otoscopy
- This is not a physiological test
- visual inspection to verify that the ear canal is not occluded, no tubes, drainage, trauma, infection, etc.
What are the three main types of Physiological Tests?
- Immittance
- Otoacoustic Emission
- Auditory Evoked Potentials
Name the two parts of Immittance Testing:
- Tympanogram
- Acoustic Reflexes
What does Immittance Testing measure and in what units is it measured in?
- It measures acoustic immittance vs impedance
- immittance units in cm3 or mmho
- daPa/decapascals units of ear canal pressure
what are the 4 primary components of immittance testing?
- transducer
- air pump
- manometer
- microphone
Tympanometry … main points
- the first part of immittance testing
- measures the flexibility of the eardrum and how sound bounces back toward microphone as pressure changes (daPa)
- used to diagnose middle ear pathologies
A tympanogram creates _____________ with a ______ and mechanically changes the air pressure in the ear canal (_______________). It also creates a tone of ______ Hz
- an airtight seal with a probe tip
- (+200 to -400 daPa compared to atmosphere)
- 226 Hz
In infants younger than 12 months of age, we use _______ Hz tone due to the __________________.
- 1000 Hz
- smaller diameter of the ear drum
Peak immittance is at the point of _____________________.
Maximum Displacement
Zero on a tympanogram =
normal
inner and outer pressure are equal
other info on Tympanograms:
- it is rare to see a positive
- scar tissue can lead to abnormal readings due to lack of flexibility
- A = normal
- lower than A is deep
- Above A is stiff
If pressure behind the eardrum is very _______ then there is an issue with the Eustachian tube. If it is ______ then there is no movement.
- negative
- flat
Tympanogram reading of A=
peak compliance between +100 and -100 daPa
Tympanogram reading of As=
peak compliance normal but very shallow (less than 0.3 mmho)
Tympanogram reading of Ad=
peak compliance normal but very deep (grater than 1.4 mmho)
Tympanogram reading of C=
peak compliance is negative pressure (beyond -100 daPa to -400 daPa)
Tympanogram reading of B=
Flat tracing with no peak (malfunction, fluid, perforation or tube)
Ear canal volume
Normative values for ear canal sizes …
- less than 0.3 the tip may be against the canal wall
- greater than 0.2 may be measuring beyond the ear canal
- 0.4-1.0 normal for kids less than 7 yrs
- 0.6-1.5 average size for adults
Acoustic Reflex testing …
-Needs a normal tympanogram
(tubes or fluid=CNT)
-measure of the acoustic arc including afferent and efferent systems
-used to diagnose retrocochlear pathologies, can suggest pathologies of the VIII nerve or brainstem
-can be measured ipsilateral (afferent) or contralateral (efferent)
-occurs at the peak pressure of the eardrum
-test at 500, 1k, 2k 3k and 4k
-helps predict levels of hearing loss
-modern tech can self determine responses
Acoustic reflex decay testing
- tone continues for ten seconds
- if reflex decays by %50 or more it is abnormal
- often used when suspecting a vestibular schwannoma
Otoacoustic Emissions (OAE) …
- a test of cochlear function
- can be spontaneous or evoked
- low level sounds create a cochlear response that can be recorded in the ear canal
- separates cochlear from retrocochlear pathologies
- separates sensory from neural
- requires a normal conductive system (outer/middle ear)
Otoacoustic Emissions were discovered by _________ in _______ and was clinically available by the __________.
- David Kemp
- 1978
- early 90’s
What are the three kinds of evoked emissions that are used for testing?
- Transient Evoked (TEOAE)
- Distortion Product (DPOAE)
- Stimulus Frequency (SFOAE)
Transient Evoked (TEOAE) …
-uses a broadband click stimulus
-pass or fail
-typically used as a screener
-used in Universal Newborn Hearing Screening (Not present if hearing loss is greater than 30 dBHL)
-Does not give frequency specific info
-uses computer averaged data collection
-has artifact rejection software
(Poor seal, crying, talking, moving, equipment noise, nursery, NICU, use of oxygen equipment)
What can interfere with TEOAE/
-Poor seal, crying, talking, moving, equipment noise, nursery, NICU, use of oxygen equipment
Distortion Product (DPOAE) …
- uses 2 frequencies 2(f1-f2) at 2 different intensities (L1 and L2)
- measures the distortion product of 2 simultaneous frequencies
- L1 and L2 separated by 15 dB SPL (65/50)
- frequency specific info
- can elicit response in moderate hearing loss or less
- Test frequencies 1000-8000Hz
- (high frequency equip. used in ototoxicity monitoring)
- distortion product is 60 dB SPL less than the two stimulus tones
Compromised patients of DPOAE?
-cognitive, autism, severe disabilities
Stimulus Frequency (SFOAE) …
-clinically, not very useful, not used outside research
Auditory Evoked Potential Testing …
- Computerized technology gathers and averages thousands of responses
- averages out random info to tease the response (potential) out of the genera muscle/neural activity
- uses typical time frames for each potential (referred to as latencies)
Early potentials in evoked potential testing …
- IHC (inner hair cell function) and VIII nerve
- exogenous: impacted by movement, talking, etc.
- not impacted by sedation
Late potentials in evoked potential testing…
- Central system
- endogenous: resistant to movement and noise
- impacted by sedation
Other uses of evoked potential testing:
- estimate hearing loss levels
- interoperative monitoring
- ANSD diagnostics
- site of lesion/retrocochlear diagnosis
- CAPD testing
Stimulus frequencies of evoked potential testing:
-click
-500 Hz
-1k Hz
-4k Hz
(all tone bursts)
Stimulus levels for evoked potential testing and the two main types:
- 90 dB nHL for neural integrity
- descending levels of hearing loss evaluation typically beginning at 80dB nHL for threshold detection
- Far Field Recordings
- Near Field Recordings
Far Field Recordings:
- electrodes placed on the forehead, top of head and each ear (earlobe or mastoid)
- ABR, AMIP, ASSP, LEP
Near Field Recordings:
- Needle electrode placed through the eardrum/middle ear and placed on the cochlea
- called ECochG
- Most often used in interoperative monitoring and research
ABR: Auditory Brainstem Response Screening
- Automated equipment used in Newborn screening test, noted as AABR
- tested at 35 dB nHL with click stimulus
- pass/fail only
- only waves 1 and 5 are visible to Newborns
ABR diagnostic
- Can test down to 20 dBHL in sound booth
- Can perform frequency specific testing
- Can use masking
ABR stimulus rates
- Typically 11-33 / sec
- Slower rate may improve waveform morphology
ABR data collection
- Sweeps of 2000-4000
- Higher numbers of sweeps may improve morphology
ABR normative data
- Correction factors to dBHL
- Different for males and females
- Newborn data collected separately
If morphology is poor _____________
suspect retrocochlear
ABR interpretation of Conductive hearing loss:
-Delayed wave 1, inter peak latencies normal
ABR interpretation of Sensorineural hearing loss:
- Delayed wave 1, hard to detect this wave
- Interpeak 1-5 latency shortened
ABR interpretation of Retrocochlear pathology:
- Wave 1 normal latency
- Waves 2-5 delayed
- Interpeak latencies abnormal
ABR is a test of ___________
Neural integrity
What is the full test battery for new borns?
- tympanometry
- acoustic reflex testing
- OAE
- ABR
Electrocochleography (ECochG) …
- measures three waves from VIII nerve to the brainstem
- AP action potential ABR wave 1
- SP summating potential hair cell activity
- uses near field recording
- stimulus short tone bursts
- may help diagnose m’s disease
Auditory Middle Latency Responses AMLR…
- Far field recordings
- Longer time frame (8-50ms)
- slow stimulus rate
- lower frequency
- record at same time as ABR
- amplitude increases from infancy to adolescence
- Pa is bilateral response with unilateral stimuli
Auditory Steady rate response ASSR…
-aka steady state evoked potential
-1,2024 ms time frame
-1 time frame = epoch
16 epochs/16 seconds=1 sweep
-p300 most studied
-used in CAPD diagnosis
-cannot be sedated and not yet in clinical use
Late evoked potentials…
- Pb (P1) 50-80ms
- N1 100-150 ms
- P2 150-200 ms
- N2 180-250 ms
-Used in 5 ms bursts
Latencies ___________________.
mature over time
