Sensorineural Hearing Loss (SNHL)
Tuning Fork Tests (Rinne vs. Weber)
| Test | Conductive Hearing Loss (CHL) | Sensorineural Hearing Loss (SNHL) |
|---|---|---|
| Rinne Test (512 Hz) | Negative (Bone Conduction ≥ Air Conduction) | Positive (Air Conduction > Bone Conduction in both ears) |
| Weber Test (512 Hz) | Lateralizes to the affected/diseased ear | Lateralizes to the BETTER (normal/healthy) ear |
NEET PG “Must-Know” Etiologies & Clinical Pearls
- Presbycusis: Age-related, progressive, bilateral high-frequency SNHL caused by degeneration of the organ of Corti.
- Ménière’s Disease: Endolymphatic hydrops. Classic triad: Episodic vertigo, tinnitus, and fluctuating low-frequency SNHL.
- Acoustic Neuroma (Vestibular Schwannoma): Benign tumor of CN VIII at the cerebellopontine (CP) angle. Presents with unilateral progressive SNHL and tinnitus. Associated with Neurofibromatosis Type 2 (bilateral tumors).
- Noise-Induced Hearing Loss: Chronic exposure damages outer hair cells. Characterized by a pathognomonic acoustic dip/notch at 4000 Hz (4 kHz) on pure tone audiometry.
- Ototoxicity: Aminoglycosides (e.g., gentamicin), loop diuretics (e.g., furosemide), cisplatin, and high-dose salicylates primarily affect the outer hair cells or stria vascularis.
- Pure Tone Audiometry (PTA): Both air conduction and bone conduction thresholds are depressed evenly, leaving no Air-Bone Gap (ABG < 15 dB).