Impedance audiometry

It is a useful tool to assess the middle ear function.

1. Clinical Utility of Impedance Audiometry Audiometry Interpretation Dr Shrikant Phatak Consultant & Head of ENT Deptt Choithram Hospital Indore

2. Clinical Utility of Impedance Audiometry A valuable objective test that provides information about the state of Middle ear. A tone delivered into the ear is partly absorbed by sound conducting apparatus & partly reflected by the tympanic membrane. There is maximum absorption of sound when the pressure on the either sides of tympanic membrane is equal. Sound reflected by tympanic membrane by varying air pressure in the external canal.

3. Clinical Utility of Impedance Audiometry P arameters which assess middle ear function are Static compliance External canal volume Middle ear pressure Acoustic reflexes Eustachian tube Function

4. Clinical Utility of Impedance Audiometry A Normal Middle ear function ,B Middle ear effusion, C Negative Middle ear pressure D Hypermobile TM or Ossicular discontinuity , As ossicular fixation

5. Clinical Utility of Impedance Audiometry Mixed Deafness PTA Grommet insertion corrects middle ear component

6. Clinical Utility of Impedance Audiometry B curve Left

7. Clinical Utility of Impedance Audiometry Low Static Compliance indicates Ossicular fixation which can be Otosclerosis ,Congenital Ossicular fixation Right 0.17ml thick foot plate than left0.28ml although PTA can be symmetrical in Both the ears

8. Clinical Utility of Impedance Audiometry In Otosclerosis this indicates even if PTA thresholds are symmetrical Left foot plate is thin

9. Clinical Utility of Impedance Audiometry PTA in Larger negative pressures More than --100 dapa need Grommets

10. Clinical Utility of Impedance Audiometry PTA thresholds in mild negative pressure Such patients respond to medical treatment

11. Clinical Utility of Impedance Audiometry Middle Ear effusion with Air Fluid Level Needs Grommet Insertion

12. Clinical Utility of Impedance Audiometry A sound intensity 70 dB above the hearing threshold is presented to the ear the Stapedius muscle contracts and alters the impedance values . This useful to diagnose Malingering Detect roughly Pure tone thresholds in small children & infants. To localize the site of lesion in cases of Facial Paralysis. Indirectly indicates presence of Recruitment. Presence of Reflex Decay indicates Retro cochlear pathology like Acoustic Neuroma

13. Clinical Utility of Impedance Audiometry The information contained in the presentation is based on the personal experience and cases collected at Choithram Hospital Indore over the last 20 years. It is intended for the use of Medical students ENT& Pediatric post graduates and the students of Audiology The views expressed are purely on personal opinion. viewers can make their own opinion. For any confusion please contact sole author. Everybody is allowed to copy or download the material best suited to him. I am not responsible for any controversies arising out of the presentation. For any suggestions or corrections you may please contact [email protected]

14. Clinical Utility of Impedance Audiometry Thank you