hear loss conduct slides 080604 (1)
TRANSCRIPT
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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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Conductive Hearing Loss andCarharts Notch
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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Conductive Hearing Loss andCarharts Notch
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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Frequency Wavelength Period
Amplitude Intensity Speed Direction
Cycles per second (Hz)
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Frequency Wavelength Period
Amplitude Intensity Speed Direction
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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Frequency Wavelength Period Amplitude Intensity Speed Direction
The amplitude is a nonnegativescalar measure of a wave'smagnitude of oscillation
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Frequency Wavelength Period Amplitude Intensity Speed Direction
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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Frequency Wavelength Period Amplitude Intensity Speed Direction
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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Frequency Wavelength Period Amplitude Intensity Speed Direction
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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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Conductive Hearing Loss andCarharts Notch
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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Conductive Hearing Loss andCarharts Notch
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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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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Conductive Hearing Loss andCarharts Notch
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
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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 andCarharts Notch
Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carharts Notch Diagnostic Implications of Carharts Notch
Conductive Hearing Loss and
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Conductive Hearing Loss andCarharts Notch
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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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