On pure tone audiometry, a patient shows air-conduction thresholds of 50 dB HL at all frequencies with bone-conduction thresholds of 10 dB HL. The tympanogram is type As (shallow). Which diagnosis is most consistent?

• A Ossicular chain discontinuity
• B Otosclerosis ✓
• C Meniere's disease
• D Acoustic neuroma

Explanation

Otosclerosis characteristically shows a maximal conductive hearing loss (air–bone gap) with a type As (reduced compliance/stiff) tympanogram due to fixation of the stapes footplate, which reduces stiffness-related tympanic membrane mobility. Bone conduction may show a Carhart's notch at 2 kHz. Ossicular discontinuity typically gives a type Ad (high compliance, floppy) tympanogram. Meniere's disease and acoustic neuroma produce sensorineural loss.

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

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Written and medically reviewed by the StethoPrep medical team.