Tympanometry of a 30-year-old man with slowly progressive bilateral conductive hearing loss shows normal middle ear pressure but markedly reduced peak compliance (a shallow, low-amplitude curve). Which diagnosis does this Type As tympanogram best support?
- A Middle ear effusion
- B Stapes fixation from otosclerosis ✓
- C Ossicular chain discontinuity
- D Eustachian tube obstruction
Correct answer: B. Stapes fixation from otosclerosis
Explanation
Type As shows normal peak pressure but reduced compliance, meaning the system is stiff but not under negative pressure. Increased stiffness of the ossicular chain from stapes fixation in otosclerosis or from tympanosclerosis produces this tracing. Effusion and Eustachian tube obstruction give Type C or Type B patterns with shifted or absent peaks. Discontinuity makes the system flaccid, giving the hypercompliant Type Ad curve, the opposite finding.
Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.