A 72-year-old man with a 10-year history of gradually progressive bilateral hearing loss presents to the audiology clinic. Pure tone audiometry shows a bilateral high-frequency sensorineural hearing loss with an air-bone gap of <10 dB. Speech discrimination is reduced. What is the most common cause of sensorineural hearing loss in this age group?

## Diagnosis: Presbycusis (Age-Related Hearing Loss) **Key Point:** Presbycusis is the most common cause of sensorineural hearing loss in the elderly, affecting approximately 1 in 3 people over age 65 and 1 in 2 over age 75. It is a bilateral, progressive, high-frequency loss due to cochlear aging. ### Epidemiology & Pathophysiology | Feature | Presbycusis | Sudden SNHL | Acoustic Neuroma | Ototoxicity | |---------|-------------|-------------|------------------|-------------| | **Age group** | Elderly (>60) | Any age | Middle-aged | Any age | | **Onset** | Gradual (years) | Acute (hours–days) | Gradual (months–years) | Variable (days–weeks) | | **Bilateral/Unilateral** | Bilateral (symmetric) | Usually unilateral | Unilateral | Bilateral (often) | | **Frequency pattern** | High-frequency loss | Variable | High-frequency loss | High-frequency loss | | **Associated symptoms** | None | Tinnitus, vertigo | Tinnitus, vertigo, facial nerve palsy | Tinnitus, vertigo (ototoxic drugs) | | **Prevalence** | ~30% >65 yrs | 5–20 per 100,000 | Rare (1 per 100,000) | Depends on drug exposure | ### Pathophysiology of Presbycusis 1. **Cochlear hair cell loss** (outer hair cells first) → high-frequency loss 2. **Strial atrophy** → reduced endolymphatic potential 3. **Basilar membrane stiffening** → reduced frequency discrimination 4. **Central auditory processing decline** → reduced speech discrimination ### Clinical Features - **Bilateral, symmetric, high-frequency SNHL** (first affected: 4–8 kHz) - **Gradual onset over years to decades** - **Reduced speech discrimination** (disproportionate to pure tone loss) - **Tinnitus** (variable) - **No vertigo** (distinguishes from vestibular pathology) - **Air-bone gap <10 dB** (confirms sensorineural, not conductive) ### High-Yield: Why Not the Other Options? **Warning:** The key discriminators are **age**, **bilaterality**, **gradual onset**, and **high-frequency pattern**. - **Sudden SNHL:** Acute onset (hours–days), usually unilateral, medical emergency - **Acoustic neuroma:** Unilateral, progressive over months–years, associated with tinnitus and vertigo; rare - **Ototoxic medication:** Requires exposure history (aminoglycosides, cisplatin, loop diuretics); bilateral but acute–subacute onset **Clinical Pearl:** The **reduced speech discrimination disproportionate to pure tone thresholds** is a hallmark of presbycusis and reflects central auditory processing decline, not just cochlear damage. ### Management - **Hearing aids** — first-line - **Cochlear implants** — for severe-to-profound loss - **Auditory rehabilitation** — speech therapy, communication strategies - **Counseling** — address psychosocial impact (depression, isolation) **Mnemonic:** **PRESBYCUSIS** = **P**rogressive **R**esolution **E**lderly **S**ensorineural **B**ilateral **Y**ears **C**ochlear **U**tility **S**uffering **I**mpaired **S**peech [cite:Scott-Brown's Otolaryngology 8e Ch 3.18; Harrison 21e Ch 431]