Which of the following findings is characteristic of sensorineural hearing loss on audiometry?

Explanation

## Audiometric Findings in Sensorineural Hearing Loss **Key Point:** In sensorineural hearing loss, **both air conduction (AC) and bone conduction (BC) thresholds are elevated equally**, resulting in **no air-bone gap** (gap < 10 dB). ### Pathophysiology Sensorineural hearing loss results from damage to the **cochlea** (inner ear) or **auditory nerve** (CN VIII). Both air and bone conduction pathways ultimately converge at the cochlea, so damage at or beyond this point affects both routes equally. 1. **Air conduction pathway:** External ear → Middle ear → Cochlea → Auditory nerve → Brain 2. **Bone conduction pathway:** Skull vibrations → Cochlea → Auditory nerve → Brain 3. When the cochlea or nerve is damaged, **both pathways are affected equally**. 4. Result: AC threshold ≈ BC threshold (parallel elevation, no gap). ### Comparison: Conductive vs Sensorineural | Feature | Conductive Loss | Sensorineural Loss | | --- | --- | --- | | **AC threshold** | Elevated | Elevated | | **BC threshold** | Normal | Elevated | | **Air-bone gap** | Present (20–60 dB) | Absent (< 10 dB) | | **AC vs BC** | AC > BC (air worse) | AC ≈ BC (parallel) | | **Site of lesion** | External/middle ear | Cochlea/auditory nerve | | **Audiogram pattern** | Conductive curve | Sensorineural curve | **High-Yield:** **No air-bone gap = sensorineural loss. Presence of air-bone gap = conductive loss.** **Clinical Pearl:** The **air-bone gap** is the single most important audiometric finding to distinguish conductive from sensorineural loss. In sensorineural loss, the gap is absent because both pathways are equally compromised. [cite:Dhingra 8e Ch 3; Robbins 10e Ch 29]