hear loss conduct slides 080604 (1)

7/31/2019 Hear Loss Conduct Slides 080604 (1)

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Conductive Hearing Loss andCarharts Notch

Mark Domanski, M.D.Tomoko Makishima, M.D., Ph.D

University of Texas Medical Branch

Department of OtolaryngologyGrand Rounds PresentationJune 4, 2008


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Physics of Sound Physics of Conductive Hearing

Tympanogram and the Acoustic Reflex Physiopathology of Carharts Notch Diagnostic Implications of Carharts Notch


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Frequency Wavelength Period

Amplitude Intensity Speed Direction


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Cycles per second (Hz)


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distance between repeating units ofa propagating wave


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Frequency Wavelength Period Amplitude Intensity Speed Direction

Implication of a repeating event


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The amplitude is a nonnegativescalar measure of a wave'smagnitude of oscillation


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intensity is a measure of the energyflux.

"intensity" is not synonymous with"strength", "amplitude", or "level


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Sound Intensity is Analogous toElectrical Flux

If a point source is radiating energy in three dimensions and there is noenergy lost to the medium, then the intensity decreases in proportion todistance from the object squared

http://web.ncf.ca/ch865/graphics/ElectricFlux


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distance such a wave travels per unit time

speed 770 mph, or 1130 ft/s) in dry air at70 degrees F

speed of sound

increases with the stiffness of the material decreases with the density


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Resonance:The tendency of a system to oscillate at maximum amplitude at certain frequencies

Small periodic driving forces can produce largeamplitude vibrations

If the monkey pushes the ball at the naturalfrequency (fundamental frequency) of the swing,the ball will go higher and higher

resonanceno resonance


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Haunted Swing

http:// www.youtube.com/watch?v=l54W2gM-gYM
http://www.youtube.com/watch?v=l54W2gM-gYMhttp://www.youtube.com/watch?v=l54W2gM-gYMhttp://www.youtube.com/watch?v=l54W2gM-gYMhttp://www.youtube.com/watch?v=l54W2gM-gYM


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Pitch not an objective physical

property

a subjectivepsychophysical attribute

perceived fundamentalfrequency of a sound

perceived pitch may differbecause of overtones, orpartials, in the sound.


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Timbre

Why two guitars sound different even when they play thesame note

the psychoacoustician's multidimensional wastebasketcategory

S McAdams , A Bregman, Hearing Musical Streams, Computer Music Journal, 1979.


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Sound Pressure Level

As the human ear can detect sounds witha very wide range of amplitudes, sound

pressure is often measured as a level on alogarithmic decibel scale.


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Frequency Weighting

human hearingsystem is moresensitive tosomefrequencies thanothers


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Frequency Weighting

humans hear random noisedifferently from pure tones

D curve designed for measuringaircraft noise

A weighting is most common

C, B, frequency weighingcurves have fallen out of use


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Sound level, loudness and soundintensity are not the same things


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medicine.swu.ac.th/webmed/EL/Oph/doc/Conductive%20hearing%20loss-pleng.ppt


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Purpose of ME

To transmit sound energy from the airspace in the EAC to the fluid in the

cochlea

This is accomplished by vibration of the

ossicles

Adapted from The Acoustic Reflex, Richard W.Harris, Ph.D., Brigham Young University


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So what if we didnt have a TM or any ossicles?

most sound energy would bounce off the ovalwindow

~30 dB hearing loss

Purpose of the TM and the ossicles is to eliminateIMPEDANCE MISMATCH Area advantage Lever advantage

IMPEDANCE the resistance to flow of energy


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Impedance Mismatch

Pool

sun


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Area AdvantageTM

OW

Adapted from The Acoustic Reflex, Richard W.Harris, Ph.D., Brigham Young University


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Area & Lever Ratio

17 * 1.3 = _______

therefore the overall increase in pressure equals:

20 Log 22 = _________________

22 to 1

26.84 dB or 27 dB


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Hearing by Bone Conduction

1. Distortional2. Inertial Ossicular

3. Osseotympanic


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Distortional Conductive Hearing


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Distortional Conductive Hearing

Left: Cochlea at rest Middle: Cochlear duct is shortened vertically, causing an

upward movement of the basilar membrane Right: Cochlear duct is heightened vertically, causing a

downward movement of the basilar membrane


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Distortional Conductive HearingCompression of the cochlea

causes a downwardmovement of the basilarmembranes. This occursbecause the round window

yields more than the oval window.

Further downward movementof the basilar membranecauses deflection of thesteriocilia and stimulation ofthe auditory nerve.

scala vestibuli

scala tympani


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Inertial Ossicular


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Inertial Ossicular


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Jerger-Liden Classifications

A


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Some Fluid or Ossicular Fixation

AS


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Ossicular Disarticulation, Atrophic TympanicMembrane Scarring

AD

Middle Ear Effusion TM Perforation


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Middle Ear Effusion, TM Perforation,Cerumen Occlusion

B


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Negative Middle Ear Pressure

C


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The Acoustic Reflex


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Normal Acoustic Reflex

Impedance


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Up to 40% Normal Persons

Impedance


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d d


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Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carharts Notch Diagnostic Implications of Carharts Notch


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Uncertain Beginnings

Miot in 1890 reported that he had usedKessels techniques to mobilize 200stapes without a single death or

labyrinthine complication!

1900: International Congress ofOtolaryngologists condemned stapessurgery because of the potential to causemeningitis


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Knowledge Expands

1916: Holmgren demonstrated that the labyrinthcould be safely opened with sterile techniques

Raymond Thomas Carhart in 1950 first used theterm air-bone gap

1953: Rosen accidentally mobilized the stapesof a patient under local anesthesia The patients hearing improved


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Breakthrough Occurs

1956 Shea, first stapedectomy with amicroscope

1960, Shea inserted a Teflon piston into asmall fenestra

1960, Schuknecht used a stainless steelwire prosthesis placed against Gelfoam toseal the oval window


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Decline in Case Volume

late 1970s: 1st publication recognizing adecline in stapedectomy cases ? backlog of surgical cases before 1960 that

had been completed ? fluoride water

? immunization for measles virusVrabec, Jeffrey T.; Coker, Newton J. Otosclerosis , Otology & Neurotology.

25(4):465-469, July 2004. Retrospective review of public records of population and case demographics

S d P i


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Stapedectomy Patients areGetting Older

Evidence of Increased Average Age ofPatients with Otosclerosis

Arnold W, Husler R (eds): Otosclerosis and Stapes Surgery.Adv Otorhinolaryngol. Basel, Karger, 2007, vol 65, pp 17-24

Retrospective chart review


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Incidence of Stapedectomies


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Incidence of Stapedectomieshas Declined


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Absolute # of Ear Surgeries

Caughey, Robert J.; Pitzer, Geoffrey B.; Kesser, Bradley W. Stapedectomy:Demographics in 2006, Otology & Neurotology Volume 27(6), Sept. 2006, pp 769-775

-retrospective review


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Carharts Notch

Carhart notch


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Carharts Notch

Elevation of bone conduction thresholds:~5dB at 4000Hz~10 db at 1000 Hz~15 db at 2000 Hz~5 db at 4000 Hz


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Tonndorf

Early 1970s Described ossicular inertial component

of total bone conduction magnitude of the Carhart notch

depended on the extent the middle earcontributed to the total bone conduction

response in each of several species tested


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Tonndorf

Early 1970s frequency of the notch varied depending

on the resonant frequency of theossicular chain for bone-conductedsignals. The resonant frequency of the human

ossicular chain was at a relatively highfrequency compared with other species.

lowest in cats and highest in rats.


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Tonndorf

Early 1970s Proposed that the Carhart notch peaks

at 2,000 Hz due to the loss of the middleear component close to the resonancepoint of the ossicular chain

Carharts Notch is Not Present in
http://www.youtube.com/watch?v=QjrEkG870ko


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Carhart s Notch is Not Present inEvery Patient with Otosclerosis

Early otosclerosismay not affect theentire stapes

footplate Cochlear

otosclerosis can

cause a SNHLcomponent

Conductive Hearing Loss and


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Conductive Hearing Loss and


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Yasan, 2007

Carharts notch can appear in: otosclerosis primary malleus fixation otitis media with effusion

Yasan, Predictive role of Carharts notch in pre -operative assessment formiddle-ear surgery. J. of Laryngology & Otology (2007), 121, 219-221.


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Yasan, 2007

Inclusion Criteria depression of bone

conduction thresholdof > 10 dB at 0.5 4

kHz frequencies CHL improved after

surgery

Exclusion Criteria Unsuccessfully

operated ears (ie, > 20 dB air-bone

gap)

Ears with Carhartsnotch at > 4 kHz

305 patientsretrospective chart review


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Yasan, 2007

Prevalence of patients with a condition whohave Carharts notch (at 1 or 2 kHz): Otosclerosis: 73 %

Tympanosclerosis : 20 % Chronic otitis media: 12 % O.M.E.: 7.1%

Ossicular anomaly 5.0%


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Yasan, 2007

If you have a Carharts notch in otosclerosisat 2kHz, you are likely to find a fixedstapedial footplate.

Stapes footplate fixation present: 1 kHz 2 out of 11 patients 2 kHz 32 out of 37 patients


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Yasan, 2007

Mean magnitude of Carharts notch was16.44 +/- 4.35 dB

Observed no specific relationship betweenmagnitude and middle ear pathologyobserved

Quantifying the Carhart Effect in


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Quantifying the Carhart Effect inOtosclerosis

What is the effect?

Problem You dont know the

true bone

threshold tillafterwards

Cook, Krishnan, Fagan, Quantifying the Carhart Effect in Otosclerosis. Clin.

Otolaryngol. 1995, 20, 258-261.

Quantifying the Carhart Effect in


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Quantifying the Carhart Effect inOtosclerosis

Change in Bone conduction is partially dependent upon airbone gap closure. To model the effect of Carharts notch,we can express change in bone conduction as a functionof change in air conduction.

dBC = change in bone conductiondAC = change in air conductionCC = frequency depended Carhart co-efficientK = frequency dependent constant

ABGC = air-bone gap closure

Pre Op Post Op


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Pre OpBC 1 15

air bone gap 25

AC1 40

Post OpBC2 5

air bone gap 5

AC2 10

dBC

dBC

dBC

ABCG

Kcc

dBC dBC


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ABCG

Kcc

dAC

Now we can do ourregression


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Conclusion

dBC

dAC

f


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References Cook, Krishnan, Fagan, Quantifying the Carhart Effect in Otosclerosis. Clin.Otolaryngol. 1995, 20, 258-261.

Yasan, Predictive role of Carharts notch in pre -operative assessment for middle-earsurgery. J. of Laryngology & Otology (2007), 121, 219-221.

Yves Pelletier, Physics animations http://web.ncf.ca/ch865/graphics/ElectricFlux.jpeg www.homeschoolmath.net/worksheets/equation_editor.php The Acoustic Reflex, Richard W. Harris, Ph.D., Brigham Young University Vrabec, Jeffrey T.; Coker, Newton J. Otosclerosis, Otology & Neurotology. 25(4):465-

469, July 2004. Arnold W, Husler R (eds): Otosclerosis and Stapes Surgery. Adv Otorhinolaryngol. Basel, Karger, 2007, vol 65,

pp 17-24 Caughey, Robert J.; Pitzer, Geoffrey B.; Kesser, Bradley W. Stapedectomy:

Demographics in 2006, Otology & Neurotology Volume 27(6), Sept. 2006, pp 769-775 Ohtani, Iwao; Baba, Yohko; Suzuki, Tomoko; Suzuki, Chiaki; Kano, Makoto,

Otosclerosis, Otology & Neurotology. Why Is Otosclerosis of Low Prevalence inJapanese? 24(3):377-381, May 2003.Handbook of Clinical Audiology, 5 th Edition, Jack Katz, Baltimore, MD, 2002.
http://web.ncf.ca/ch865/graphics/ElectricFlux.jpeghttp://www.homeschoolmath.net/worksheets/equation_editor.phphttp://www.homeschoolmath.net/worksheets/equation_editor.phphttp://web.ncf.ca/ch865/graphics/ElectricFlux.jpeg

hear loss conduct slides 080604 (1)

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