Which audiometric pattern is characteristic of presbycusis (age-related sensorineural hearing loss)?

Explanation

## Presbycusis: Audiometric Pattern **Key Point:** Presbycusis presents as a **high-frequency sensorineural hearing loss** with a characteristic **downsloping audiometric curve**. ### Pathophysiology Presbycusis results from age-related degeneration of the cochlea, particularly affecting the basal turn (high-frequency region). The cochlea's frequency map is tonotopic: - **Base (basal turn):** High frequencies (4–8 kHz) - **Apex (apical turn):** Low frequencies (125–500 Hz) Age-related atrophy preferentially damages basal cochlear hair cells and stria vascularis, causing **high-frequency loss first**. ### Audiometric Features | Feature | Presbycusis | Noise-Induced | Conductive | |---------|-------------|---------------|------------| | Type | Sensorineural | Sensorineural | Conductive | | Pattern | Downsloping (high-freq worse) | 4 kHz notch | Air-bone gap | | Onset | Gradual, bilateral, symmetric | Acute/chronic | Variable | | AC-BC gap | <10 dB | <10 dB | >10 dB | ### Characteristic Curve ``` Hearing Threshold (dB HL) 0 ├───────────────────────────── 10 │ ● 20 │ ● 30 │ ● 40 │ ●● 50 │ ●● 60 │ ●●● 70 │ ●●● └───────────────────────────── 125 250 500 1k 2k 4k 8k (Hz) ↑ Low freq (normal) High freq (worse) ↑ [Downsloping curve] ``` **High-Yield:** Presbycusis = **sensorineural + high-frequency loss + downsloping curve + bilateral symmetric + gradual onset**. **Clinical Pearl:** Patients with presbycusis often complain of difficulty hearing speech in noisy environments (recruitment phenomenon) and tinnitus. They hear low-frequency sounds (door slam, traffic) but miss high-frequency consonants (s, f, th).