A patient receiving gentamicin for pyelonephritis is monitored for cochleotoxicity. Which method detects the earliest evidence of ototoxic injury?

• A High-frequency audiometry above 8 kHz ✓
• B Conventional pure tone audiometry at 250 to 8000 Hz
• C Tympanometry
• D Speech recognition threshold testing

Explanation

Aminoglycosides destroy outer hair cells starting at the basal turn of the cochlea, which encodes the highest frequencies. Damage therefore begins above 8 kHz, well outside the conventional audiometric range, and descends apically toward the speech frequencies. High-frequency audiometry detects the loss weeks before standard audiometry becomes abnormal, allowing dose adjustment. Tympanometry assesses middle ear status and cannot detect cochlear damage.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.