A 68-year-old woman from Mumbai presents with insidious onset of bilateral hearing loss over 2 years, worse for high-frequency sounds. She denies tinnitus or vertigo. Otoscopy is normal. Weber test shows lateralization to the left ear. Rinne test demonstrates air conduction better than bone conduction bilaterally, with no air-bone gap. Pure tone audiometry shows a characteristic 'cookie-bite' or high-frequency dip pattern. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Presbycusis (Age-Related Sensorineural Hearing Loss) ### Defining Audiological Features **High-Yield:** The **absence of air-bone gap** with **AC > BC on Rinne test** is the hallmark of sensorineural hearing loss. Combined with the characteristic **high-frequency dip** pattern on audiometry, this confirms presbycusis. **Key Point:** Presbycusis is the most common cause of sensorineural hearing loss in the elderly, resulting from age-related degeneration of inner ear hair cells, particularly affecting high frequencies. ### Interpretation of Audiological Tests | Test | Finding | Interpretation | |------|---------|----------------| | **Rinne Test** | AC > BC bilaterally | Air conduction better than bone conduction — **sensorineural loss** | | **Weber Test** | Lateralizes to left | Indicates sensorineural loss on the **right** (sound travels better through bone to the better ear) | | **Air-Bone Gap** | Absent (0 dB) | No gap confirms sensorineural pathology, not conductive | | **Audiometry Pattern** | High-frequency dip | Characteristic of presbycusis; low frequencies relatively preserved | | **Otoscopy** | Normal | Rules out external/middle ear disease | ### Presbycusis: Clinical Hallmarks 1. **Age of onset:** Typically >60 years (this patient is 68) 2. **Bilateral and symmetrical:** Progressive, gradual loss 3. **High-frequency loss:** Affects speech discrimination, especially consonants 4. **No vertigo or tinnitus:** Distinguishes from other inner ear pathologies 5. **Insidious progression:** Over years, not sudden ### Differential Diagnosis: Why Not Otosclerosis? **Otosclerosis** would present with: - **Conductive or mixed hearing loss** (not pure sensorineural) - **Air-bone gap present** (this patient has none) - **Carhart notch** at 2 kHz (not high-frequency dip) - Typically affects younger patients (30–50 years) - Often unilateral or asymmetrical ### Clinical Pearl The **'cookie-bite' or high-frequency dip pattern** on audiometry is virtually pathognomonic for presbycusis. This pattern reflects selective loss of outer hair cells in the basal turn of the cochlea, which processes high frequencies. The normal otoscopy and absence of vertigo/tinnitus further support age-related degeneration rather than acute or inflammatory pathology. ### Mnemonic: SENSORINEURAL HEARING LOSS — NO ABG **N** = No air-bone gap **O** = Outer/inner ear pathology (not middle ear) **A** = AC > BC on Rinne **B** = Both ears affected equally in presbycusis **G** = Gradual, progressive onset