A 52-year-old man from Delhi presents with progressive bilateral hearing loss over 6 months. He reports difficulty hearing conversations, especially in noisy environments. Otoscopy reveals normal tympanic membranes bilaterally. Weber test shows lateralization to the right ear. Rinne test demonstrates bone conduction better than air conduction bilaterally. Pure tone audiometry shows air-bone gap of 35 dB at 2 kHz bilaterally. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Conductive Hearing Loss ### Key Audiological Findings **High-Yield:** The presence of an **air-bone gap (ABG) of 35 dB** is the diagnostic hallmark of conductive hearing loss. This gap represents the difference between air conduction (AC) and bone conduction (BC) thresholds. **Key Point:** In conductive hearing loss, bone conduction is preserved because sound bypasses the external and middle ear to directly stimulate the inner ear. Air conduction is impaired because the pathology lies in the conductive pathway. ### Interpretation of Audiological Tests | Test | Finding | Interpretation | |------|---------|----------------| | **Rinne Test** | BC > AC | Bone conduction better than air conduction — **conductive loss** | | **Weber Test** | Lateralizes to right | Indicates conductive loss on the right (sound travels better through bone to affected ear) | | **Air-Bone Gap** | 35 dB | Significant gap confirms conductive pathology | | **Otoscopy** | Normal TM | Rules out obvious TM perforation; suggests ossicular or Eustachian tube pathology | ### Differential Considerations **Sensorineural hearing loss** would show: - AC = BC (no air-bone gap) - Rinne: AC > BC - Weber lateralizes to the **better ear** (left in this case) **Mixed hearing loss** would show: - Both AC and BC thresholds elevated - Air-bone gap present but smaller than pure conductive loss - Combination of both pathologies ### Clinical Pearl Bilateral conductive hearing loss with normal otoscopy suggests **otosclerosis** (most common cause in this age group), **ossicular fixation**, or **Eustachian tube dysfunction**. The progressive nature over 6 months and bilateral involvement make otosclerosis the most likely diagnosis in a 52-year-old. ### Mnemonic: CONDUCTIVE HEARING LOSS — ABG **A** = Air-bone gap present **B** = BC better than AC on Rinne **G** = Gap indicates middle ear/conductive pathway disease