On impedance audiometry, a patient with otosclerosis is expected to show which tympanogram type, and what acoustic reflex pattern?
- A Type B (flat) tympanogram; absent acoustic reflex due to fluid in the middle ear
- B Type C (negative peak) tympanogram; present acoustic reflex at elevated thresholds
- C Type As (reduced compliance) tympanogram; absent ipsilateral acoustic reflex at all frequencies ✓
- D Type A (normal) tympanogram; present acoustic reflex with 'on-off effect'
Correct answer: C. Type As (reduced compliance) tympanogram; absent ipsilateral acoustic reflex at all frequencies
Explanation
In otosclerosis, the stapedial footplate becomes fixed in the oval window, greatly reducing middle ear compliance. Tympanometry shows a Type As (shallow/reduced amplitude) peak due to stiffness. The acoustic reflex is absent ipsilaterally because the stapedius reflex requires movement of the stapes, which is fixed. Contralaterally, it may also be absent. The 'on-off effect' (Metz recruitment) refers to increased reflex decay and is seen in cochlear lesions, not otosclerosis. Type C indicates Eustachian tube dysfunction.
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.