A 54-year-old man has a pure tone average of 40 dB in the right ear, but his speech discrimination score in that ear is 22 percent, far worse than the degree of hearing loss would predict. Stapedial reflex decay is positive on the right. These findings localise the lesion to the:

• A Cochlea, consistent with Meniere's disease
• B Ossicular chain, consistent with otosclerosis
• C Brainstem auditory pathways only, with a normal eighth nerve
• D Eighth nerve or cerebellopontine angle, consistent with a vestibular schwannoma ✓

Explanation

Disproportionately poor speech discrimination relative to the pure tone average, along with positive stapedial reflex decay, indicates a retrocochlear lesion because neural firing becomes desynchronised before pure thresholds fall markedly. Cochlear (sensory) losses show good discrimination scores and often loudness recruitment with absent reflex decay. Conductive losses preserve discrimination entirely. This pattern mandates MRI of the internal auditory meatus to exclude vestibular schwannoma.

Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.