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Impedance audiometry part 1

audiometry

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Impedance audiometry part 1

  1. 1. Aditya Ghosh Roy PGT2 MS ENT
  2. 2. • USE • TEST TYMPANOMETRY EUSTACHIAN TUBE FUNCTION STAPEDIAL REFLEX
  3. 3. SOUND WAVE SOUND WAVE SOLID AIR AIR ABSORBED SOUND
  4. 4. SOUND AIR SOLID IMPEDANCE STIFF NESS MASS FRICTIO N
  5. 5. AIR COCHLEA SOUND MIDDLE EAR IMPEDANCE MATCHING DEVICE COCHLE A EAC T M
  6. 6. • CHANGE IN PRESSURE --- CHANGE IN TM STIFFNESS ---SOUND ENERGY REFLECTED BACK DEPENDS ON STIFFNESS OF TM OR PRESSURE CHANGE PROBE TONE AMPLIFIER MANOMETE R S O U N D TYMPANIC MEMBRANE REFLECT ED SOUND P R E S S U R E
  7. 7. • THEREFORE TYMPANOMETRY MAY BE DEFINED AS MEASUREMENT OF CHANGE IN IMPEDANCE OF MIDDLE EAR CAVITY AT THE TM PLANE IN RELATION TO CHANGE IN PRESSURE IN EAC. • TYMPANOGRAM Y or ORDINATE IMPEDANCE OR STIFFNESS X OR ABSCISSA AIR PRESSURE
  8. 8. • IMPEDANCE • NONE OF THE PARAMETERS MEASURED INDIVIDUALLY SO AS A RESULT ACOUSTIC ADMITTANCE IS MEASURED ADMITTANCE IS RECIPROCAL OF IMPEDANCE STIFFNESS MASS FRICTION IMPEDANCE OPPOSITION TO FLOW OF ENERGY ACOUSTIC OHM ADMITTANCE EASE TO FLOW OF ENERGY ACOUSTIC MHO
  9. 9. • AUDIOMETERS STILL AUDIOMETERS DO NOT MEASURE ADMITTANCE DIRECTLY COMPLIANCE LOW FREQUENCY PROBE TONE USED IMPEDANCE EASE OF MOVEMENT OR SPRINGINESS OF MIDDLE EAR SYSTEM IS ALSO RECIPROCAL OF STIFFNESS
  10. 10. • HENCE IF COMPLIANCE IS MEASURED USING LOW FREQUENCY TONE • IMPEDANCE OF MIDDLE EAR SYSTEM • MOST OF THE IMPEDANCE AUDIOMETERS MEASURE COMPLIANCE
  11. 11. • C1 – COMPLIANCE VALUE AT +200mm water • C2 – COMPLIANCE VALUE AT (MAXIMUM) • CX – STATIC COMPLIANCE (C2- C1=CX)
  12. 12. • PRESSURE AT WHICH COMPLIANCE VALUE IS MAXIMUM IS CALLED AS MIDDLE EAR PRESSURE IE PRESSURE OF AIR IN MIDDLE EAR CAVITY.
  13. 13. THE COMPLIANCE VALUE AT +200mM water IS THE VOLUME OF EAC .
  14. 14. TYMPANOMETRY MEASUREMENT OF STATIC COMPLIANCE MEASUREMENT OF MIDDLE EAR PRESSURE
  15. 15. • cc/ ml if COMPLIANCE • Millimho if SUSPECTANCE • IF A 220 Hz PROBE– 1MILLIMHO OF SUSPECTANCE = 1 CC/ML OF COMPLIANCE TYMPANOGRAM ABSOLUTE RELATIVE COMPENSATED
  16. 16. • BASELINE IS COMPLIANCE AT +200 • SHADED AREA IS VOLUME OF EAC • ALSO CALLED NON COMPENSATED TYPE ABSOLUTE • BASELINE IS 0 AT ORDINATE • BRACKET PORTION IS COMPLIANCE RELATIVE • BASELINE IS 0 AT ORDINATE • BRACKET PORTION IS COMPLIANCE • SHADED AREA BESIDE THE TYMPANOGRAM IS VOLUME OF EAC COMPENSATED
  17. 17. • NORMAL RANGE COMPLIANCE • IMP POINT– CLINICAL CONDITION OF TM TO BE ALWAYS NOTED • STUDY BY A.S. FELDMAN– HEALED TM INVALIDATES COMPLIANCE AS ONE OF THE TESTS OF TYMPANOMETRY .35 TO 1.40 ML > 2.50mL < .28 mL ABNORMALLY HIGH ABNORMALLY LOW
  18. 18. LARGE TM OSSICULAR DISCONTINUITY SCARED/HEALED TM POST STAPEDECTOMY EAR OTITIS MEDIA WITH EFFUSION OSSICULAR FIXATION TYMPANOSCLERO SIS OTOSCLEROSIS TUMOUR OF MIDDLE EAR
  19. 19. • EXPRESSED IN mm WATER / DEKA PASCAL (daPa) • 1mm WATER = 1.20 DEKA PASCAL • RANGE = +50 TO -50 mm WATER • MEP NEGATIVE WHEN P < -100 mm WATER • PAED AGE GROUP-- +25 TO -100mm WATER
  20. 20. NORMAL MEP • SCARRED TM • OSICULLAR FIXATION • OSICULLAR DISCONTUINITY • STAPEDIAL OTOSCLEROSIS NEGATIVE MEP • ET DYSFUNCTION • SECRETORY OTITIS MEDIA/EFFUSION
  21. 21. ABSENCE OF PEAK • PERFORATED TM • ADHESIVE OTITIS MEDIA • ARTIFACT • PATENT GROMET IN TM • CERUMEN POSITIVE MEP • EARLY ACUTE OTITIS MEDIA
  22. 22. • SWALLOWING • CHILD CRYING PHYSIOLOGICAL • VALSALVA • HOLD BREATH IN EXPIRATION • IN EARLY AOM PUS FORMED IN MEC AND ET DYSFUNCTION DECREASE VOLUME + INCREASE PRESSURE OF MEC POSITIVE PRESSURE PEAK
  23. 23. TYMPANOGRAMS J. JERGER A B A.S. FELDMAN
  24. 24. • SHARP MAXIMUM AT 0 mm WATER • NORMAL EAR AND SOME CASES OF OTOSCLEROSIS
  25. 25. • NORMAL MIDDLE EAR PRESSURE WITH HIGH COMPLIANCE • SEEN IN OSSICULAR CHAIN DISCONTUINITY OR SCARRING OF TM • NOTCHED PEAK OR DOUBLE MAX AT 0 mm USUALLY SEEN WITH A HIGH FREQUENCY PROBE IN OSSICULAR DISCONTUINITY
  26. 26. • NORMAL MIDDLE EAR PRESSURE WITH LOW COMPLIANCE • OTOSCLEROSIS AND THICKENED TM
  27. 27. • FLAT TYMPANOGRAM • LITTLE OR NO COMPLIANCE AND NO SHARP PEAK • SEEN IN ADHESIVE OTITIS MEDIA, OTITIS MEDIA WITH EFFUSION, PERFORATION OF TM
  28. 28. • NEGATIVE MIDDLE EAR PRESSURE WITH NORMAL COMPLIANCE • ET DYSFUNCTION WITHOUT EFFUSION
  29. 29. • NEGATIVE MIDDLE EAR PRESSURE WITH LOW COMPLIANCE • ET DYSFUNCTION WITH OTITIS MEDIA WITH EFFUSION
  30. 30. PEAK PRESSURE TYPE OF CONFIGURATION OF TYMPANOGRAM COMPLIANCE OR AMPLITUDE
  31. 31. 1.NORMAL TYMPANO GRAM • GOOD COMPLIANCE AND PEAK PRESSURE AT 0 mm WATER • CORRESPONDS TO JAGER TYPE A
  32. 32. 2.NORMAL MIDDLE EAR PRESSURE WITH HIGH COMPLIANCE • IF 226HZ PROBE USED THEN EITHER OSSICULAR CHAIN DISCONTUINITY OR SCARRING OF TM • BUT IF A 660 OR 800 HZ PROBE USED THEN A NOTCHED PEAK OR DOUBLE MAX AT 0 mm USUALLY SEEN IN OSSICULAR DISCONTUINITY
  33. 33. 3.NORMAL MIDDLE EAR PRESSURE WITH LOW COMPLIANCE • OTOSCLEROSIS OR OSSICULAR FIXATION AND THICKENED TM
  34. 34. 4. FLAT TYMPANOGRAM • LITTLE OR NO COMPLIANCE AND NO SHARP PEAK • SEEN IN ADHESIVE OTITIS MEDIA, OTITIS MEDIA WITH EFFUSION, PERFORATION OF TM . • CORRESPONDS TO JAGER TYPE B.
  35. 35. 5.NEGATIVE MIDDLE EAR PRESSURE WITH LOW COMPLIANCE • ET DYSFUNCTION WITH OTITIS MEDIA WITH EFFUSION • CORRESPONDS TO JAGER TYPE CS
  36. 36. 6. POSITIVE MIDDLE EAR PRESSURE NORMAL COMPLIANCE • RARELY SEEN • IN EARLY AOM IN EARLY AOM PUS FORMED IN MEC AND ET DYSFUNCTION DECREASE VOLUME + INCREASE PRESSURE OF MEC POSITIVE PRESSURE PEAK
  37. 37. 7.NEGATIVE MIDDLE EAR PRESSURE WITH NORMAL COMPLIANCE • ET DYSFUNCTION WITHOUT EFFUSION
  38. 38. TO BE CONT..

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