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Conductive Hearing Loss and Carhart s Notch

Conductive Hearing Loss and Carhart's Notch. Physics of SoundPhysics of Conductive HearingTympanogram and the Acoustic ReflexPhysiopathology of Carhart's NotchDiagnostic Implications of Carhart's Notch. Conductive Hearing Loss and Carhart's Notch. Physics of SoundPhysics of Conductive HearingTympanogram and the Acoustic ReflexPhysiopathology of Carhart's NotchDiagnostic Implications of Carhart's Notch.

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Conductive Hearing Loss and Carhart s Notch

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    1. Conductive Hearing Loss and Carhart’s Notch Mark Domanski, M.D. Tomoko Makishima, M.D., Ph.D University of Texas Medical Branch Department of Otolaryngology Grand Rounds Presentation June 4, 2008

    2. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

    3. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

    4. Frequency Wavelength Period Amplitude Intensity Speed Direction

    5. Frequency Wavelength Period Amplitude Intensity Speed Direction

    6. Frequency Wavelength Period Amplitude Intensity Speed Direction

    7. Frequency Wavelength Period Amplitude Intensity Speed Direction

    8. Frequency Wavelength Period Amplitude Intensity Speed Direction

    9. Frequency Wavelength Period Amplitude Intensity Speed Direction

    10. Sound Intensity is Analogous to Electrical Flux http://web.ncf.ca/ch865/graphics/ElectricFlux.jpeg Physics animations by Yves Pelletier http://web.ncf.ca/ch865/graphics/ElectricFlux.jpeg Physics animations by Yves Pelletier

    11. Frequency Wavelength Period Amplitude Intensity Speed Direction

    12. Frequency Wavelength Period Amplitude Intensity Speed Direction

    13. Resonance: The tendency of a system to oscillate at maximum amplitude at certain frequencies Small periodic driving forces can produce large amplitude vibrations If the monkey pushes the ball at the natural frequency (fundamental frequency) of the swing, the ball will go higher and higher http://regentsprep.org/Regents/physics/phys04/bresonan/default.htmhttp://regentsprep.org/Regents/physics/phys04/bresonan/default.htm

    14. Haunted Swing

    15. Pitch not an objective physical property a subjective psychophysical attribute perceived fundamental frequency of a sound perceived pitch may differ because of overtones, or partials, in the sound.

    16. Timbre Why two guitars sound different even when they play the same note “the psychoacoustician's multidimensional wastebasket category “ S McAdams, A Bregman, Hearing Musical Streams, Computer Music Journal, 1979. S McAdams, A Bregman, Hearing Musical Streams, Computer Music Journal, 1979.

    17. Sound Pressure Level As the human ear can detect sounds with a very wide range of amplitudes, sound pressure is often measured as a level on a logarithmic decibel scale.

    18. Frequency Weighting human hearing system is more sensitive to some frequencies than others

    19. Frequency Weighting

    20. Sound level, loudness and sound intensity are not the same things

    21. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

    22. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

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

    24. Purpose of ME To transmit sound energy from the air space in the EAC to the fluid in the cochlea This is accomplished by vibration of the ossicles

    25. So what if we didn’t have a TM or any ossicles? most sound energy would bounce off the oval window ~30 dB hearing loss Purpose of the TM and the ossicles is to eliminate IMPEDANCE MISMATCH Area advantage Lever advantage IMPEDANCE – the resistance to flow of energy Impedance mismatch :: energy in one medium encountering another medium Impedance :: how easy it is to set a particular thing/medium into motionImpedance mismatch :: energy in one medium encountering another medium Impedance :: how easy it is to set a particular thing/medium into motion

    26. Impedance Mismatch

    27. Area Advantage

    28. Lever Advantage

    29. Area & Lever Ratio 17 * 1.3 = _______ therefore the overall increase in pressure equals: 20 Log 22 = _________________

    30. Hearing by Bone Conduction Distortional Inertial – Ossicular Osseotympanic

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

    32. 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 Cyclic changes in the otic capsule during distortional component of bone conduction stimulation. 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 membraneCyclic changes in the otic capsule during distortional component of bone conduction stimulation. 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

    33. Distortional Conductive Hearing Compression of the cochlea causes a downward movement of the basilar membranes. This occurs because the round window yields more than the oval window. Further downward movement of the basilar membrane causes deflection of the steriocilia and stimulation of the auditory nerve. Different phases of compressional bone conduction. The cochlea at rest, with the basilar membrane represented by the middle line with the scala vestibuli above and scala tympani below. Compression of the cochlea causes a downward movement of the basilar membranes. This occurs because the round window yields more than the oval window. Further downward movement of the basilar membrane causes deflection of the sternocilla and stimulation of the auditory nerve. Bone conduction: The vibration of the bones of the skull elicits auditory sensation. At lest three bone-conduction mechanisms can transmit sounds and cause the same activity in the cochlea. Bone conduction can be used as a way to bypass the outer and middle ears and to stimulate the cochlea. Tonndorf (1972) describes three mechanisms of bone-conduction hearing. In normal, healthy ears these thee mechanisms work together to produce activity in the cochlea. The cochlear response is the same as that produced by airborne signals. Verification of this phenomenon comes from the work by von Bekesy (1939), who demonstrated that by phase shifting, a bone-conduction signal introduced at the forehead could cancel out the activity in the cochlea caused by an airborne signal that was delivered through an earphone. Bone conduction works because the cochlea is housed within the temporal bone. The bones of the skull are all connected. This allows energy applied to one part of the skull to radiate throughout the entire skull, including, of course, the temporal bone. Barany (1938) and Herzog and Krainz (1926) were among the first to describe significant contributions of the different structures to bone-conduction hearing. Tonndorf (1968) suggested that there are three primary components of bone-conduction hearing. Each contributes in some way to the threshild of force needed to set the inner ear in motion and produce the sensation of hearing.Different phases of compressional bone conduction. The cochlea at rest, with the basilar membrane represented by the middle line with the scala vestibuli above and scala tympani below. Compression of the cochlea causes a downward movement of the basilar membranes. This occurs because the round window yields more than the oval window. Further downward movement of the basilar membrane causes deflection of the sternocilla and stimulation of the auditory nerve. Bone conduction: The vibration of the bones of the skull elicits auditory sensation. At lest three bone-conduction mechanisms can transmit sounds and cause the same activity in the cochlea. Bone conduction can be used as a way to bypass the outer and middle ears and to stimulate the cochlea. Tonndorf (1972) describes three mechanisms of bone-conduction hearing. In normal, healthy ears these thee mechanisms work together to produce activity in the cochlea. The cochlear response is the same as that produced by airborne signals. Verification of this phenomenon comes from the work by von Bekesy (1939), who demonstrated that by phase shifting, a bone-conduction signal introduced at the forehead could cancel out the activity in the cochlea caused by an airborne signal that was delivered through an earphone. Bone conduction works because the cochlea is housed within the temporal bone. The bones of the skull are all connected. This allows energy applied to one part of the skull to radiate throughout the entire skull, including, of course, the temporal bone. Barany (1938) and Herzog and Krainz (1926) were among the first to describe significant contributions of the different structures to bone-conduction hearing. Tonndorf (1968) suggested that there are three primary components of bone-conduction hearing. Each contributes in some way to the threshild of force needed to set the inner ear in motion and produce the sensation of hearing.

    34. Conductive hearing loss medicine.swu.ac.th/webmed/EL/Oph/doc/Conductive%20hearing%20loss-pleng.ppt Once classic example of the contribution of the inertial-ossicular contribution is the effecto of otosclerosis on bone-conduction and air-conduction hearing thresholds. Fixation of the stapes has the effect of increasing the stiffness of the ossciular chain. When one tests the bone conduction threshold, a “notch” (a depressed threshold known as “Carhart’s notch,” appears to be a decrease in cochlear sensitivity. This effect is greatest at 2 kHZ, which actually represents the loss of the inertial-ossicular mode of bone conduction as a result of the fixation (Carhart, 1950, Carhart, 1962). The decrease occurs at 2 kHz because this is the resonant frequency of the ossicular chain in humans. Following surgical repair of the ossicular chain, the bone-conduction thresholds often improve. Conductive hearing loss medicine.swu.ac.th/webmed/EL/Oph/doc/Conductive%20hearing%20loss-pleng.ppt Once classic example of the contribution of the inertial-ossicular contribution is the effecto of otosclerosis on bone-conduction and air-conduction hearing thresholds. Fixation of the stapes has the effect of increasing the stiffness of the ossciular chain. When one tests the bone conduction threshold, a “notch” (a depressed threshold known as “Carhart’s notch,” appears to be a decrease in cochlear sensitivity. This effect is greatest at 2 kHZ, which actually represents the loss of the inertial-ossicular mode of bone conduction as a result of the fixation (Carhart, 1950, Carhart, 1962). The decrease occurs at 2 kHz because this is the resonant frequency of the ossicular chain in humans. Following surgical repair of the ossicular chain, the bone-conduction thresholds often improve.

    35. Inertial – Ossicular Application of force from the mastoid bone. This causes a relatively large movement between the skull and ossicular chain. This vibrational force along the axis of movement causes a movement of the stapes and oval window. Application of force from the forehead. The movement of the skull is perpendicular to the axis of the ossicular chain, resulting in no movement of the stapes.Application of force from the mastoid bone. This causes a relatively large movement between the skull and ossicular chain. This vibrational force along the axis of movement causes a movement of the stapes and oval window. Application of force from the forehead. The movement of the skull is perpendicular to the axis of the ossicular chain, resulting in no movement of the stapes.

    36. Conductive hearing loss medicine.swu.ac.th/webmed/EL/Oph/doc/Conductive%20hearing%20loss-pleng.ppt Occlusion Effect The example that best illustrates the external ear component of bone conduction is occlusion. Occlusion may be artificially induced by covering the external ear with a headphone or seen naturally as the result of pathologic conditions such as cerumen impaction. When the external ear canal is occluded, the bone-conduction threshold improves. This is particularly pronounced in the lower frequencies. Handbook of Clinical Audiology, 5th edition, Jack Katz, 2002. Conductive hearing loss medicine.swu.ac.th/webmed/EL/Oph/doc/Conductive%20hearing%20loss-pleng.ppt Occlusion Effect The example that best illustrates the external ear component of bone conduction is occlusion. Occlusion may be artificially induced by covering the external ear with a headphone or seen naturally as the result of pathologic conditions such as cerumen impaction. When the external ear canal is occluded, the bone-conduction threshold improves. This is particularly pronounced in the lower frequencies. Handbook of Clinical Audiology, 5th edition, Jack Katz, 2002.

    37. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

    38. Maximum compliance of the middle ear system occurs when the pressure in the middle ear cavity is equal to the pressure in the external auditory canal. The maximum compliance value occurs at the highest peak of the curve on the graph PDF] Tympanometry File Format: PDF/Adobe Acrobat - View as HTML An acoustic reflex, or contraction of the Stapedial muscle, occurs ... A fixation of the ossicular chain, as in otosclerosis, will produce a ... www.maico-diagnostics.com/eprise/main/Maico/Products/Files/MI24/Guide.Tymp.pdf - Similar pagesMaximum compliance of the middle ear system occurs when the pressure in the middle ear cavity is equal to the pressure in the external auditory canal. The maximum compliance value occurs at the highest peak of the curve on the graph PDF] Tympanometry File Format: PDF/Adobe Acrobat - View as HTMLAn acoustic reflex, or contraction of the Stapedial muscle, occurs ... A fixation of the ossicular chain, as in otosclerosis, will produce a ...www.maico-diagnostics.com/eprise/main/Maico/Products/Files/MI24/Guide.Tymp.pdf - Similar pages

    39. Jerger-Liden Classifications Impedance Audiometry Article Last Updated: May 26, 2006 AUTHOR AND EDITOR INFORMATION Section 1 of 8   Authors and Editors Acoustic Immittance Tympanometry Less Commonly Used Tests Acoustic Reflex Thresholds Pathologies Indicated By Acoustic Reflex Patterns Multimedia References Author: Kathleen CM Campbell, PhD, Director of Audiology, Professor, Department of Surgery, Division of Otolaryngology, Southern Illinois University School of Medicine Kathleen C M Campbell is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Auditory Society, American Tinnitus Association, Association for Research in Otolaryngology, and New York Academy of Sciences Coauthor(s): Ginger Mullin, AuD, Newborn Infant Hearing Program, Division of Specialized Care for Children, State of Illinois Impedance Audiometry Article Last Updated: May 26, 2006 AUTHOR AND EDITOR INFORMATION Section 1 of 8   Authors and Editors Acoustic Immittance Tympanometry Less Commonly Used Tests Acoustic Reflex Thresholds Pathologies Indicated By Acoustic Reflex Patterns Multimedia References

    40. Some Fluid or Ossicular Fixation Impedance Audiometry Article Last Updated: May 26, 2006 AUTHOR AND EDITOR INFORMATION Section 1 of 8   Authors and Editors Acoustic Immittance Tympanometry Less Commonly Used Tests Acoustic Reflex Thresholds Pathologies Indicated By Acoustic Reflex Patterns Multimedia References Author: Kathleen CM Campbell, PhD, Director of Audiology, Professor, Department of Surgery, Division of Otolaryngology, Southern Illinois University School of Medicine Kathleen C M Campbell is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Auditory Society, American Tinnitus Association, Association for Research in Otolaryngology, and New York Academy of Sciences Coauthor(s): Ginger Mullin, AuD, Newborn Infant Hearing Program, Division of Specialized Care for Children, State of Illinois Impedance Audiometry Article Last Updated: May 26, 2006 AUTHOR AND EDITOR INFORMATION Section 1 of 8   Authors and Editors Acoustic Immittance Tympanometry Less Commonly Used Tests Acoustic Reflex Thresholds Pathologies Indicated By Acoustic Reflex Patterns Multimedia References

    41. Ossicular Disarticulation, Atrophic Tympanic Membrane Scarring

    42. Middle Ear Effusion, TM Perforation, Cerumen Occlusion

    43. Negative Middle Ear Pressure

    44. The Acoustic Reflex

    45. Anatomy

    47. Normal Acoustic Reflex Decrease admittance, compliance Increase impedanceDecrease admittance, compliance Increase impedance

    48. Up to 40% Normal Persons

    49. Fixed Anterior Footplate Tenseness vs flaccidityTenseness vs flaccidity

    50. Fixed Anterior & Posterior Footplates

    51. Acoustic Reflex Morphology

    52. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

    53. Otosclerosis Valsalva first described ankylosis of the stapes Kessel in 1878 described the first “successful stapes surgery” The patient had fallen off a wagon and struck his head. After a brief spell of unconsciousness, the patient found that his sense of hearing was greatly improved. He later died of in injuries. Kessel studied his temporal bones and concluded the stapes had been mobilized.

    54. Uncertain Beginnings Miot in 1890 reported that he had used Kessel’s techniques to mobilize 200 stapes’ without a single death or labyrinthine complication! 1900: International Congress of Otolaryngologists condemned stapes surgery because of the potential to cause meningitis

    55. Knowledge Expands 1916: Holmgren demonstrated that the labyrinth could be safely opened with sterile techniques Raymond Thomas Carhart in 1950 first used the term air-bone gap 1953: Rosen accidentally mobilized the stapes of a patient under local anesthesia The patient’s hearing improved

    56. Breakthrough Occurs 1956 Shea, first stapedectomy with a microscope 1960, Shea inserted a Teflon piston into a small fenestra 1960, Schuknecht used a stainless steel wire prosthesis placed against Gelfoam to seal the oval window

    57. Decline in Case Volume late 1970s: 1st publication recognizing a decline in stapedectomy cases ? backlog of surgical cases before 1960 that had been completed ? fluoride water ? immunization for measles virus Vrabec, Jeffrey T.; Coker, Newton J. Otosclerosis, Otology & Neurotology. 25(4):465-469, July 2004. Retrospective review of public records of population and case demographics

    58. Stapedectomy Patients are Getting Older Evidence of Increased Average Age of Patients with Otosclerosis Arnold W, Häusler R (eds): Otosclerosis and Stapes Surgery. Adv Otorhinolaryngol. Basel, Karger, 2007, vol 65, pp 17-24  Retrospective chart review

    59. Stapedectomies per Resident Declined, then Stabilized no. of self-reported stapedectomies performed during residency declined until the mid-1980s, then plateaued at the current level of 8 to 9 cases per resident. no. of self-reported stapedectomies performed during residency declined until the mid-1980s, then plateaued at the current level of 8 to 9 cases per resident.

    60. Incidence of Stapedectomies has Declined Caughey, Robert J.; Pitzer, Geoffrey B.; Kesser, Bradley W. Stapedectomy: Demographics in 2006, Otology & Neurotology Volume 27(6), Sept. 2006, pp 769-775 -retrospective reviewCaughey, Robert J.; Pitzer, Geoffrey B.; Kesser, Bradley W. Stapedectomy: Demographics in 2006, Otology & Neurotology Volume 27(6), Sept. 2006, pp 769-775 -retrospective review

    61. Absolute # of Ear Surgeries

    62. Different Ethnic Prevalence Ohtani, Iwao; Baba, Yohko; Suzuki, Tomoko; Suzuki, Chiaki; Kano, Makoto, Otosclerosis, Otology & Neurotology. Why Is Otosclerosis of Low Prevalence in Japanese? 24(3):377-381, May 2003. 1011 temporal bones from 507 Japanese individuals incidence of histological otosclerosis among Japanese 2.56% of individuals 1.48% of the ears Similar to published histological rates among Caucasians

    63. Different Ethnic Prevalence Ohtani, Iwao; Baba, Yohko; Suzuki, Tomoko; Suzuki, Chiaki; Kano, Makoto, Otosclerosis, Otology & Neurotology. Why Is Otosclerosis of Low Prevalence in Japanese? 24(3):377-381, May 2003. clinical otosclerosis was not as prevalent among Japanese low incidence of involvement of foci anterior to the oval window low activity small lesion without involvement of the footplate and/or membranous labyrinth of the inner ear.

    64. Carhart’s Notch OTOSCLEROSIS PORNTHAPE KASEMSIRI Aj. SUTHEE (Advisor) ent.md.kku.ac.th/site_data/mykku_ent/38/Topic4/otosclerosis.ppt OTOSCLEROSIS PORNTHAPE KASEMSIRI Aj. SUTHEE (Advisor) ent.md.kku.ac.th/site_data/mykku_ent/38/Topic4/otosclerosis.ppt

    65. Carhart’s Notch Elevation of bone conduction thresholds: ~5dB at 4000Hz ~10 db at 1000 Hz ~15 db at 2000 Hz ~5 db at 4000 Hz Otosclerosis and Stapedectomy, C de Souza, M. E. Glasscock III, 2004. OTOSCLEROSIS PORNTHAPE KASEMSIRI Aj. SUTHEE (Advisor) ent.md.kku.ac.th/site_data/mykku_ent/38/Topic4/otosclerosis.ppt Otosclerosis and Stapedectomy, C de Souza, M. E. Glasscock III, 2004. OTOSCLEROSIS PORNTHAPE KASEMSIRI Aj. SUTHEE (Advisor) ent.md.kku.ac.th/site_data/mykku_ent/38/Topic4/otosclerosis.ppt

    66. Tonndorf Early 1970s Described ossicular inertial component of total bone conduction magnitude of the Carhart notch depended on the extent the middle ear contributed to the total bone conduction response in each of several species tested

    67. Tonndorf Early 1970s frequency of the notch varied depending on the resonant frequency of the ossicular chain for bone-conducted signals. The resonant frequency of the human ossicular chain was at a relatively high frequency compared with other species. lowest in cats and highest in rats.

    68. Tonndorf Early 1970s Proposed that the Carhart notch peaks at 2,000 Hz due to the loss of the middle ear component close to the resonance point of the ossicular chain

    69. Carhart’s Notch is Not Present in Every Patient with Otosclerosis Early otosclerosis may not affect the entire stapes footplate Cochlear otosclerosis can cause a SNHL component R EarR Ear

    70. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

    71. Conductive Hearing Loss and Carhart’s Notch Physics of Sound Physics of Conductive Hearing Tympanogram and the Acoustic Reflex Physiopathology of Carhart’s Notch Diagnostic Implications of Carhart’s Notch

    72. Yasan, 2007 Carhart’s notch can appear in: otosclerosis primary malleus fixation otitis media with effusion

    73. Yasan, 2007 Inclusion Criteria depression of bone conduction threshold of > 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 “Carhart’s notch” at > 4 kHz

    74. Yasan, 2007 Data collected: Pre-operative diagnosis Mobility of the stapes footplate Presence of Carhart’s notch Peri-operative middle ear pathology Improvement of hearing loss Disappearance of Carhart’s notch

    75. Yasan, 2007

    76. Yasan, 2007 Prevalence of patients with a condition who have Carhart’s notch (at 1 or 2 kHz): Otosclerosis: 73 % Tympanosclerosis : 20 % Chronic otitis media: 12 % O.M.E.: 7.1% Ossicular anomaly 5.0% This is not that clinically usefulThis is not that clinically useful

    77. Yasan, 2007 If you have a Carhart’s notch in otosclerosis at 2kHz, you are likely to find a fixed stapedial footplate. Stapes footplate fixation present: 1 kHz 2 out of 11 patients 2 kHz 32 out of 37 patients

    78. Yasan, 2007 Mean magnitude of Carhart’s notch was 16.44 +/- 4.35 dB Observed no specific relationship between magnitude and middle ear pathology observed

    79. Quantifying the Carhart Effect in Otosclerosis What is the effect? Problem You don’t know the true bone threshold till afterwards

    80. Quantifying the Carhart Effect in Otosclerosis Change in Bone conduction is partially dependent upon air bone gap closure. To model the effect of Carhart’s notch, we can express change in bone conduction as a function of change in air conduction. dBC = change in bone conduction dAC = change in air conduction CC = frequency depended Carhart co-efficient K = frequency dependent constant ABGC = air-bone gap closure

    81. Pre Op BC1 15 air bone gap 25 AC1 40 Post Op BC2 5 air bone gap 5 AC2 10 dBC = cc(ABGC) + K ABCG = (AC1 - AC2) - (BC1 - BC2) ABCG = (dAC) - (dBC) dBC = cc ((dAC) - (dBC)) + K dBC = cc (dAC) - cc(dBC) + K dBC + cc (dBC) = cc(dAC) + K dBC(1 + cc) = cc(dAC) + K dBC = (cc(dAC) + K) / (1 + cc) dBC = (cc/ (1+CC)) * dAC + (K/(1+cc)) dBC = cc(ABGC) + K ABCG = (AC1 - AC2) - (BC1 - BC2) ABCG = (dAC) - (dBC) dBC = cc ((dAC) - (dBC)) + K dBC = cc (dAC) - cc(dBC) + K dBC + cc (dBC) = cc(dAC) + K dBC(1 + cc) = cc(dAC) + K dBC = (cc(dAC) + K) / (1 + cc) dBC = (cc/ (1+CC)) * dAC + (K/(1+cc))

    82. Online Equation Editor http://www.homeschoolmath.net/worksheets/equation_editor.phpOnline Equation Editor http://www.homeschoolmath.net/worksheets/equation_editor.php

    83. Quantifying the Carhart Effect in Otosclerosis

    84. Conclusion

    85. References Cook, Krishnan, Fagan, Quantifying the Carhart Effect in Otosclerosis. Clin. Otolaryngol. 1995, 20, 258-261. Yasan, Predictive role of Carhart’s notch in pre-operative assessment for middle-ear surgery. 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, Häusler 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 in Japanese? 24(3):377-381, May 2003. Handbook of Clinical Audiology, 5th Edition, Jack Katz, Baltimore, MD, 2002.

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