A 30-year-old woman presents with progressive bilateral conductive hearing loss. Tympanometry shows an 'As' (shallow) curve. Audiometry reveals a characteristic notch at 2 kHz on bone conduction. The most likely diagnosis is:
- A Secretory otitis media
- B Otosclerosis ✓
- C Ossicular chain disruption
- D Tympanosclerosis
Correct answer: B. Otosclerosis
Explanation
The Carhart notch — a depression of approximately 5–15 dB at 2 kHz on the bone conduction curve — is pathognomonic of otosclerosis. It is a mechanical artefact caused by the immobilised stapes reducing the contribution of ossicular inertia to bone conduction, not a true sensorineural component. The As (reduced compliance) tympanogram confirms stapes fixation. The condition affects young adults and may worsen in pregnancy.
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.