On impedance audiometry (tympanometry) a type As (shallow) tympanogram is found. This pattern is characteristically associated with:

• A Eustachian tube dysfunction with negative middle ear pressure
• B Ossicular discontinuity
• C Otosclerosis or tympanosclerosis (reduced ossicular mobility) ✓
• D Perforation of tympanic membrane

Explanation

Type As (shallow) tympanogram has a peak compliance at or near atmospheric pressure but the peak height is reduced (< 0.3 mL), indicating a stiff middle ear system. This is characteristic of otosclerosis (stapes fixation) or tympanosclerosis (calcium plaques fixing the ossicular chain). Type Ad (deep) with excessively tall peak suggests ossicular discontinuity. Type B (flat) indicates middle ear effusion or perforation; Type C indicates negative middle ear pressure from ETD.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.