A 62-year-old man presents with progressive bilateral hearing loss over 10 years. Audiometry shows bilateral sensorineural hearing loss with a characteristic bone conduction threshold of 45 dB HL and air conduction threshold of 55 dB HL at 4 kHz. The loss is more pronounced at higher frequencies. What is the most common cause of this audiometric pattern?

Explanation

## Diagnosis: Presbycusis **Key Point:** Presbycusis is the most common cause of sensorineural hearing loss in elderly populations, accounting for approximately 50% of hearing loss in adults over 60 years. ## Audiometric Features of Presbycusis | Feature | Presbycusis | Noise-Induced | Ototoxic | SSHL | |---------|-------------|---------------|----------|------| | **Onset** | Gradual (years) | Gradual (months-years) | Variable | Sudden (days) | | **Pattern** | High-frequency loss (4-8 kHz) | Notch at 4 kHz | High-frequency loss | Variable | | **Bilaterality** | Bilateral, symmetric | Bilateral, symmetric | Bilateral, symmetric | Usually unilateral | | **Air-bone gap** | None (sensorineural) | None (sensorineural) | None (sensorineural) | None (sensorineural) | | **Age of onset** | >50 years | Any age (occupational) | Any age (medication) | Any age | ## Pathophysiology of Presbycusis 1. **Cochlear changes** — Loss of outer hair cells, particularly in basal turn (high frequencies) 2. **Strial atrophy** — Degeneration of stria vascularis reduces endolymphatic potential 3. **Neural loss** — Spiral ganglion cell degeneration 4. **Mechanical changes** — Increased stiffness of basilar membrane **High-Yield:** The characteristic **high-frequency sensorineural loss (4–8 kHz) with bilateral symmetry and gradual onset over years** is pathognomonic for presbycusis. ## Clinical Pearl Presbycusis typically shows: - Bilateral, symmetric sensorineural hearing loss - Predominantly high-frequency involvement - Slow progression (10–20 dB per decade after age 60) - Speech discrimination often disproportionately affected (recruitment phenomenon) - Normal bone conduction–air conduction relationship (no air-bone gap) **Mnemonic: PRESBYCUSIS = Progressive Elderly Sensorineural Bilateral Yearly Cusis** (age-related hearing loss) ## Why This Case Fits Presbycusis - Age 62 (typical onset >50 years) - 10-year gradual progression - Bilateral symmetric loss - Higher frequency involvement (4 kHz noted) - Sensorineural pattern (air-bone gap ~10 dB is within normal limits for presbycusis)