A 52-year-old man presents with progressive bilateral hearing loss over 6 months. Otoscopy is normal. Weber test shows lateralization to the right ear, and Rinne test shows bone conduction better than air conduction bilaterally. Which investigation is most appropriate to confirm the diagnosis and assess candidacy for intervention?

## Clinical Scenario Analysis The patient presents with: - Progressive bilateral hearing loss - Normal otoscopy (rules out obvious conductive pathology) - Weber lateralization to right ear (suggests asymmetric sensorineural loss) - Rinne: bone > air conduction (indicates conductive or mixed hearing loss) ## Why Pure Tone Audiometry is the Gold Standard **Key Point:** Pure tone audiometry with bone and air conduction thresholds is the gold standard investigation for characterizing and quantifying hearing loss — both type (conductive vs. sensorineural) and severity. **High-Yield:** The air-bone gap (ABG) is the diagnostic hallmark: - ABG ≥ 15 dB = conductive or mixed hearing loss - ABG < 15 dB = sensorineural hearing loss - Bilateral ABG suggests mixed or bilateral conductive pathology ## Interpretation in This Case | Finding | Interpretation | |---------|----------------| | Bone conduction threshold | Reflects inner ear function (cochlear reserve) | | Air conduction threshold | Reflects both middle ear and inner ear | | Air-bone gap | Quantifies middle ear conductive component | **Clinical Pearl:** In this patient, despite normal otoscopy, the Rinne finding (bone > air) and Weber lateralization suggest either: 1. Bilateral conductive loss (e.g., otosclerosis, ossicular chain disruption) 2. Mixed hearing loss with a dominant conductive component Pure tone audiometry will: - Quantify the ABG at each frequency - Establish baseline for monitoring progression - Guide counseling on hearing aids vs. surgical intervention - Assess asymmetry and need for imaging **Mnemonic: ABCD of Audiometry** — Air-Bone gap, Bilateral assessment, Conductive vs. Sensorineural, Degree of loss.