A 72-year-old woman presents with gradual bilateral hearing loss affecting high frequencies more than low frequencies over 5 years. She denies vertigo, tinnitus, or ear discharge. Otoscopy is normal. Audiometry shows bone conduction thresholds of 40 dB HL at 4 kHz, 45 dB HL at 8 kHz, and air conduction thresholds of 42 dB HL at 4 kHz and 48 dB HL at 8 kHz. Speech discrimination is 72%. What is the most likely diagnosis?

## Sensorineural Hearing Loss: Presbycusis ### Audiometric Pattern Analysis **Key Point:** This audiogram shows: - **Air-bone gap:** <5 dB HL (no gap) → sensorineural hearing loss - **High-frequency loss:** 4–8 kHz affected > 500 Hz–2 kHz - **Bilateral and symmetrical** pattern - **Gradual onset over 5 years** (chronic, not sudden) - **Speech discrimination:** 72% (moderately reduced, typical of sensorineural loss) ### Why This Is Presbycusis ```mermaid flowchart TD A[Sensorineural Hearing Loss]:::outcome --> B{Pattern?}:::decision B -->|High-freq, bilateral, gradual, age >60| C[Presbycusis]:::action B -->|High-freq, unilateral, noise exposure| D[Noise-induced]:::action B -->|Sudden onset, any freq, within 2 weeks| E[SSHL]:::action B -->|Drug history, any pattern| F[Ototoxicity]:::action ``` ### Presbycusis: Definition & Pathophysiology **Presbycusis** = age-related sensorineural hearing loss 1. **Age of onset:** Typically >60 years (this patient is 72) 2. **Frequency pattern:** High-frequency loss (4–8 kHz) > low frequencies 3. **Bilaterality:** Always bilateral and symmetrical 4. **Progression:** Gradual over years (not sudden) 5. **Pathology:** Cochlear hair cell loss, strial atrophy, and neural degeneration ### Types of Presbycusis | Type | Pathology | Audiometric Pattern | Speech Discrimination | | --- | --- | --- | --- | | **Sensory** | Hair cell loss (basal turn) | High-freq loss, steep slope | Preserved initially | | **Neural** | Spiral ganglion/nerve loss | Flat or low-freq loss | Poor (disproportionate) | | **Strial** | Stria vascularis atrophy | Flat loss across frequencies | Preserved | | **Cochlear conductive** | Stiffening of basilar membrane | Gradually sloping loss | Preserved | **Clinical Pearl:** This patient's high-frequency loss with relatively preserved speech discrimination (72%) is most consistent with the **sensory type** of presbycusis, the most common form. ### High-Yield: Differential Diagnosis of Sensorineural Hearing Loss **Presbycusis:** - Age >60, gradual onset, bilateral, high-freq loss - No vertigo, tinnitus, or otalgia - Normal otoscopy **Noise-induced hearing loss:** - History of loud noise exposure (occupational or recreational) - Notch at 3–6 kHz (Carhart's notch analogue) - May be unilateral if exposure is unilateral **Sudden sensorineural hearing loss (SSHL):** - Onset within 72 hours (this patient has 5-year history) - Any frequency range affected - Often accompanied by vertigo or tinnitus **Ototoxicity:** - Medication history (aminoglycosides, cisplatin, loop diuretics, NSAIDs) - Bilateral high-frequency loss - Rapid progression (days to weeks) - Often with tinnitus and vertigo **Mnemonic: SNHL Causes (VITAMINS)** - **V**iral (mumps, measles, CMV) - **I**mmune (autoimmune inner ear disease) - **T**rauma (temporal bone fracture) - **A**ging (presbycusis) ← **This case** - **M**etabolic (hypothyroidism, diabetes) - **I**nfectious (syphilis, TB) - **N**eoplastic (acoustic neuroma, CPA lesion) - **S**ound (noise-induced) **Warning:** Do not confuse presbycusis with noise-induced hearing loss. Noise-induced loss typically shows a **notch at 3–4 kHz** and requires a clear history of noise exposure; presbycusis shows a gradual high-frequency slope without such a history. [cite:Glasscock-Shambaugh Surgery of the Ear Ch 2; Harrison 21e Ch 31]