In a pure tone audiogram showing an air-bone gap with bone conduction at 0 dB HL and air conduction at 60 dB HL, tympanometry shows a flat (Type B) curve with high compliance and large volume. What is the most likely diagnosis?

• A Ossicular chain discontinuity
• B Otitis media with effusion
• C Otosclerosis
• D Tympanic membrane perforation with patent Eustachian tube ✓

Explanation

A Type B (flat) tympanogram with a large middle ear volume (>2 cc in adults) indicates a tympanic membrane perforation — the probe is measuring the combined volume of the external canal and middle ear through the perforation. The large air-bone gap (60 dB) with normal bone conduction represents a maximal conductive hearing loss. In otitis media with effusion, the volume is within normal limits (0.5–2 cc) with flat compliance. Ossicular discontinuity produces a very high-compliance (Type AD) tympanogram. Otosclerosis shows Type As (shallow compliance) with absent stapedial reflexes.

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

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Written and medically reviewed by the StethoPrep medical team.