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141 Cards in this Set
- Front
- Back
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Immittance
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physiological test of M.E.'s ability to pass energy thru
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Function Tests
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-complement to behavioral tests
-doesn't test exact hearing sensitivity |
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admittance
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how easily energy flows thru M.E. system (infers ET funct)
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impedance
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resistance to energy flow; how a system opposes energy flow thru it
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when is admittance max?
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P of EAM = P of M.E.
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age of tympanometry
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reliable after 3 mo age
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hermetic seal
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no air leaks from probe tip to TM
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minimum admittance
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+200 daPa added to EAM
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what does tympanometry measure?
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-vol b/w probe tip & TM
-impedance of M.E. |
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what can you infer w/tympanometry?
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-mass & stiffness
-funct of M.E. & ossicles -M.E. vol |
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When is equiv. vol of EAM-TM large?
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TM perforation or PE tubes
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when is equiv. vol small?
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OM w/effusion or cerumen impaction
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what causes increased mass in the M.E.?
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fluid or disarticulated ossicles
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what causes stiffness in M.E.?
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otosclerosis
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Nml Equiv. vol EAM to TM
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infant = 0.3 to 0.9
child = 0.6 to 1.5 adult =0.6 to 2.0 |
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referral schedule for tympanometry
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>0.3 vol in under 6 yrs
>0.4 vol 6 yr + 6-8 wk |
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where does energy flow best?
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P of EAM = P of M.E. (max admittance)
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normal range for peak admittance
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+50 to -100 (0 = atmos P is perfect)
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what can you infer when peak admittance = 0?
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normal ET funct (balanced mass & stiffness of M.E.)
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normal values of peak compensated static acoustic admittance
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infant = 0.25 to 0.92
child = 0.25 to 1.5 adult = 0.3 to 1.7 |
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tympanometry units
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-determined by equip.
-mmho (actual energy) -cm^3 = cc -mL (vol) |
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Aside from immitance device & probe tip, what equip. req for tymp.?
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226Hz probe tone loudspeaker, monitor mic, P pump & manometer, ipsilateral reflex loudspeaker
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tympanogram shows (on pic)
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admittance across TM
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type A(s) tymp
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ossicular chain not vibrating fully-->reduced energy thru M.E.
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what tymp implies a nml conductive system?
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type A
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otosclerosis results in which tymp?
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type A(s)
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is ET funct in type A(s) tymp?
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yes (but ossicles stiff)
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Tymps that convey pathologies where absent acoustic reflex
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Types A(s), A(d), & B.
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type A(d) tymp
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moderate conductive HL
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causes of disarticulated ossicular chain
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-severe infection
-TBI |
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flaccid TM that vibrates w/large amplitude
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type A(d) tymp
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type B tymp
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always check vol
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increased mass that cause ossicles to not vibrate freely; ET not working
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type B tymp
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type C tymp
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P EAM > P M.E.
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type of tymp when ET not working well
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type C tymp
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risks w/type C tymp
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cholestotoma (neg P pulls TM toward M.E. space)
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what admittance is ART tested?
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max admittance (P EAM = P M.E.) where energy flows best
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ART frequency & intensity stim range
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500, 1KHz, 2KHz, 4KHz
70-110 dB SPL |
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ART threshold search
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if admittance drops, decrease by 10 dB SPL
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what dB level are we looking for in ART?
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doesn't matter--just presence/absence of reflex
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definition of acoustic reflex threshold (ART)
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min intensity to elicit change of min 0.2 mL in admittance
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what does change in admittance show in ART?
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increased impedance (ossicular chain stiffens w/stapedius contraction)
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in what test will cochlea respond even w/40 dB HTL?
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acoustic reflex present
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no acoustic reflex in SNHL usually caused by
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nerve tumor
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ART w/type A(s) tymp
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no reflex b/c ossicular chain already stiff (fixed stapes)
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T or F: cerumen impaction will cause absent acoustic reflex
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T. r/o w/otoscopy
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T or F: ART tests hearing sensitivity
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F. (no response at nml/mild threshold levels)
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physiological test that helps dx exact site of lesion
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ART
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contralateral reflex pathway
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. . .superior olivary complex---->facial nucleus-->CNVII-->stapedius muscle
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efferent in acoustic reflex pathway
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CNVII (carries motor info from brain to body)
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afferent in reflex pathway
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CNVIII (carries sensory info to brain)
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ipsilateral reflex pathway
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peripheral-->cochlear nucleus-->superior olivary complex-->facial nucleus-->CNVII-->stapedius muscle
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causes a higher acoustic reflex threshold
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worse conductive HL (absorbs stim)
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process to find acoustic reflex decay
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find ART, increase by 10 dB SPL, present stim 10 sec
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abnormal acoustic decay
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50% decrease in response before 10 sec is up
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use for acoustic decay?
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help find retrocochlear HL (b/c neural fatigue faster than norm)
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(screening) test that indirectly assess the M.E.
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otoacoustic emissions (OAE)
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OHC
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-efferent
-lateral -resp to soft sounds -3 rows |
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cochlear cells that are motile (dance)
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OHC
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what is measured in OAE?
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the unique sound created by P waves from vibrating OHC
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IHC
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-afferent
-respond to loud sounds -no stereocilia & not embedded in tectorial membrane |
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probe tip in OAE
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helps block noise & trap emission
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info derived about the nerve in OAE
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none--only tests to the cochlea (can even get an emission if sound not traveling to brain)
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OAE test considerations
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-test in quiet enviro
-no muscle mvmt |
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OAE frequency
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-high freq = larger resp
-low freq blend w/random noise |
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criteria for present emission
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+6 dB S/N over random noise
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750-8kHz
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frequencies tested in DPOAE
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first test for differential dx
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OAE (in SNHL b/c test only goes to cochlea, not nerve beyond)
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SNHL with present emission
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nerve is responsible for HL (inferred)
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SNHL with absent emission
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cochlea is responsible for HL
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no emission found in OAE test
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-otoscopy to r/o outer ear
-tympanometry to r/o M.E. |
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types of OAE
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-spontaneous = 50% ppl get OHC dance sans stim
-evoked = clin. useful |
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definition of evoked OAE
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OHC dance in response to stim
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types evoked OAE
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-transient evoked (TEOAE)
-distortion product (DPOAE) |
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what is TEOAE?
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broadband clicks that dx only flat HL
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what is DPOAE?
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2 stim freq generate a 3rd measurable prod = (2F1-F2)
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which evoked OAE is freq specific?
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DPOAE (b/c you can manipulate the 2 stim freq to get a prod on a certain region of the BM)
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which evoked OAE is binary?
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TEOAE (b/c it is multi-freq)
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DPOAE can measure what frequencies?
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20-20,000HZ, but high freq have better resp
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what does a large emission mean?
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Great dif. b/w sig. & noise means nothing. We care if it's present or not.
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T or F: evoked OAEs are threshold tests
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F (NOT a threshold test, we aren't manipulating intensities, doesn't ascertain hearing sensitivity)
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dB HTL that an emission will be present
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0 dB HTL to 30 dB HTL
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assumption about hearing level with present emission
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no more then mild HL (no emission in moderate-profound HL)
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M.E. assumptions w/present emission
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no pathology, no conductive component
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assumption about inner ear with present emission
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intact cochlea capable of resp to SOFT sounds
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OAE results in moderate to profound HL
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no emission (but we still don't know exact degree HL)
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steps after getting absent emission?
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use other dx tests to find site of lesion (OAE is a complement test)
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OAE referral schedule
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rescreen OAE-->refer = ABR (by 3 mo in newborn population)
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clinical uses for evoked OAE
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-screen (special populations)
-monitor ototoxicity -dx pseudohypoacusis -differential dx (AC = BC) |
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possible reasons for absent emission
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-too much enviro noise or mvmt
-birthing fluid in ears -operator error -HL |
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Who sets OAE pass/refer criteria?
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equip/manufacturer (non-standard; no calibration)
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absent emission, but nml audiogram
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OAE will show cochlear changes before they appear on audiogram (good monitoring tool)
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umbrella term for all tests that look at time b/w aud stim & change in neural activity (resp)
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auditory evoked potentials (AEP)
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definition of latency
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time b/w stim & resp (in msec)
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AEP latency intervals
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-early = 0-15 msec
-middle = 16-60 msec -late = 50-200 msec |
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other acronyms for auditory brainstem response
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BAER, AER, BAEP, BSER, early resp
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purpose of ABR (what affects CNVIII?)
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-screening
-thresholds -nerve tumor -dyssynchrony -M.S. |
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ABR testing considerations
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-quiet (sleeping preferred)
-no mvmt |
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another test for differential dx
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ABR (in SNHL b/c looks @ nerve & beyond)
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Gives site of lesion in SNHL when used together?
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OAE = cochlear & ABR = neural
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test to dx M.S.?
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ABR (slow resp, especially w/fast rate in demyelinated)
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age of ABR resp
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-34-35 wk gestation
-2 yr for mature resp |
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age conditions req for ABR to work
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-pneumotized M.E.
-synchronization (of CNVIII) |
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process of pneumotization
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-1st gasp stim ET
-replaces liquid in M.E. w/air |
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characteristics of an adult ABR resp
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-absolute latency
-interpeak latency -all neural generators resp (wv I-VII) |
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far-field measurements
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-electrodes on scalp (vs field = needle direct on nerve)
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electrode montage
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-forehead/vernix; reference EEG on pinna/mastoid, ground
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electrode that p/u actual aud resp
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forehead
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electrode that p/u body EEG
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reference
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types of ABR
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-transient clicks
-tone pips |
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ABR used for hearing screening
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transient clicks (broadband = range 1-4KHz; all high freq)
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ABR used to collect thresholds
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tone pips (attempt at freq-specific)
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intensity units for tone pip ABR
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dB nHL (compared to normed data)
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Neurons resp fast to transient click ABR b/c?
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sharp = fast rise & fall time; no complex info to process
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far-field req how many sweeps for morphology?
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min of 10,000 (more = better pic, takes more time)
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ABR clicks/sec
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11 (faster = fatigues neural generators)
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how to use ABR rate to dx pathology
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use neural fatigue (slow = resp & faster = falls apart) to dx retrocochlear
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in ABR collect own norms for
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-age
-gender -latency-intensity function |
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definition of absolute latency
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wave peak over time
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definition of interpeak latency
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distance b/w waves (I-V = 4 msec)
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ABR interpretation looks at:
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-morphology
-latency: absolute/interpeak/interaural |
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ABR wave I corresponds to
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cochlear nucleus (CNVIII)
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ABR wave III corresponds to
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superior olivary complex (according to B.P.)
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ABR wave V corresponds to
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inferior colliculus (all synapse here)
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ABR in conductive HL
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all waves = delayed latency; nml interpeak latency
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ABR in SNHL
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wv I morphology poor; short interpeak (I delayed, V nml)
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ABR in retrocochlear HL
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all waves = poor morphology; long interpeak (I nml, V delayed)
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interaural latency max difference
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0.2 msec or less
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interaural latency is slower in 1 ear
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suspect nerve tumor (unilateral)
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age for conditioned play audm
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2 yr and up
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age for VRA
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(maybe 4 mo) 5mo to 2yr
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age for BOA
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birth to 4-5-ish mo
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pediatric behavioral tests
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-BOA
-VRA -conditioned play audm -speech audm |
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behavioral observation audm (BOA) responses
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-blink, widen, engage w/eyes
-change sucking pattern -startle (always 65 dB) |
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test w/very rapid habituation?
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BOA (subtle & limited resp)
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VRA procedure
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-condition (noise)
-resp (head turn) -reward (lighted toy) = operant conditioning |
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approx dB level VRA will test
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20 dB (depends on age & stim)
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test that utilizes behavioral conditioning & shaping
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conditioned play audm (train + praise)
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-block in box
-pegs in board |
exp of conditioned play audm activities
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speech audm used for
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AC & BC thresholds (not freq-specific)
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provides freq-specific info
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-filtered speech
-narrow-band noise -DPOAE -pure tone tests |
