Impedance audiometry part 1

audiometry

1. IMPEDANCE AUDIOMETRY Aditya G hosh Roy PGT2 MS ENT

2. IMPEDANCE AUDIOMETRY USE TEST TYMPANOMETRY EUSTACHIAN TUBE FUNCTION STAPEDIAL REFLEX

3. SOUND WAVE SOUND WAVE SOLID RELECTED SOUND WAVE AIR AIR ABSORBED SOUND

4. SOUND AIR SOLID REFLECTED SOUND

5. IMPEDANCE SOUND MIDDLE EAR IMPEDANCE MATCHING DEVICE COCHLEA EAC TM

6. TYMPANOMETRY (DEF) CHANGE IN PRESSURE --- CHANGE IN TM STIFFNESS ---SOUND ENERGY REFLECTED BACK DEPENDS ON STIFFNESS OF TM OR PRESSURE CHANGE PROBE TONE AMPLIFIER MANOMETER S OU N D TYMPANIC MEMBRANE REFLECTED SOUND PRESSURE

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. 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. 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. HENCE IF COMPLIANCE IS MEASURED USING LOW FREQUENCY TONE IMPEDANCE OF MIDDLE EAR SYSTEM MOST OF THE IMPEDANCE AUDIOMETERS MEASURE COMPLIANCE

11. IMPORTANT POINTS C1 – COMPLIANCE VALUE AT +200mm water C2 – COMPLIANCE VALUE AT (MAXIMUM) CX – STATIC COMPLIANCE (C2- C1=CX) STATIC COMPLIANCE IS DEFINED AS COMPLIANCE OF AUDITORY CONDUCTIVE PATHWAY AT TM.

12. MIDDLE EAR PRESSURE PRESSURE AT WHICH COMPLIANCE VALUE IS MAXIMUM IS CALLED AS MIDDLE EAR PRESSURE IE PRESSURE OF AIR IN MIDDLE EAR CAVITY.

13. PHYSICAL VOLUME TEST VALUE THE COMPLIANCE VALUE AT +200mM water IS THE VOLUME OF EAC .

14. TYMPANOMETRY MEASUREMENT OF STATIC COMPLIANCE MEASUREMENT OF MIDDLE EAR PRESSURE

15. MEASUREMENT OF STATIC COMPLIANCE cc/ ml if COMPLIANCE Millimho if SUSPECTANCE IF A 220 Hz PROBE– 1MILLIMHO OF SUSPECTANCE = 1 CC/ML OF COMPLIANCE TYMPANOGRAM

16. 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

17. MEASUREMENT OF MIDDLE EAR PRESSURE 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

18. IMP POINT--POSITIVE PRESSURE PEAK 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

19. TYPES AND SHAPES OF TYMPANOGRAMS

20. TYPE A SHARP MAXIMUM AT 0 mm WATER NORMAL EAR AND SOME CASES OF OTOSCLEROSIS

21. TYPE AD 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

22. TYPE AS NORMAL MIDDLE EAR PRESSURE WITH LOW COMPLIANCE OTOSCLEROSIS AND THICKENED TM

23. TYPE B FLAT TYMPANOGRAM LITTLE OR NO COMPLIANCE AND NO SHARP PEAK SEEN IN ADHESIVE OTITIS MEDIA, OTITIS MEDIA WITH EFFUSION, PERFORATION OF TM

24. TYPE C NEGATIVE MIDDLE EAR PRESSURE WITH NORMAL COMPLIANCE ET DYSFUNCTION WITHOUT EFFUSION

25. TYPE CS NEGATIVE MIDDLE EAR PRESSURE WITH LOW COMPLIANCE ET DYSFUNCTION WITH OTITIS MEDIA WITH EFFUSION

26. CLASSIFICATION BY A.S. FELDMAN PEAK PRESSURE TYPE OF CONFIGURATION OF TYMPANOGRAM COMPLIANCE OR AMPLITUDE

27. 1.NORMAL TYMPANO GRAM GOOD COMPLIANCE AND PEAK PRESSURE AT 0 mm WATER CORRESPONDS TO JAGER TYPE A

28. 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

29. 3.NORMAL MIDDLE EAR PRESSURE WITH LOW COMPLIANCE OTOSCLEROSIS OR OSSICULAR FIXATION AND THICKENED TM

30. 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.

31. 5.NEGATIVE MIDDLE EAR PRESSURE WITH LOW COMPLIANCE ET DYSFUNCTION WITH OTITIS MEDIA WITH EFFUSION CORRESPONDS TO JAGER TYPE CS

32. 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

33. 7.NEGATIVE MIDDLE EAR PRESSURE WITH NORMAL COMPLIANCE ET DYSFUNCTION WITHOUT EFFUSION

34. TO SUMMARISE

35. TO BE CONT..