On pure-tone audiometry, a patient has air conduction thresholds of 50 dB at 500 Hz and 55 dB at 1000 Hz, with bone conduction thresholds of 5 dB at both frequencies. Acoustic immittance testing shows a type B tympanogram. The most likely diagnosis is:
- A Otitis media with effusion — conductive hearing loss with flat tympanogram ✓
- B Sensorineural hearing loss — cochlear origin
- C Otosclerosis — conductive hearing loss with normal middle ear pressure
- D Auditory neuropathy spectrum disorder
Correct answer: A. Otitis media with effusion — conductive hearing loss with flat tympanogram
Explanation
The audiogram shows a 45–50 dB air-bone gap (AC 50–55 dB, BC 5 dB) — significant conductive hearing loss. Type B tympanogram (flat, with no compliance peak) indicates absence of tympanic membrane mobility, characteristic of middle ear effusion (otitis media with effusion) or tympanic membrane perforation. In otosclerosis, tympanogram is typically type A (normal or As — shallow compliance), and there is a characteristic Carhart notch at 2000 Hz on BC. SNHL shows AC and BC thresholds equally reduced. ANSD shows abnormal ABR with normal/present OAEs.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.