A 45-year-old man presents with progressive unilateral hearing loss and tinnitus. Pure-tone audiometry shows mild-to-moderate sensorineural hearing loss (PTA 35 dB). Speech audiometry reveals a word recognition score (WRS) of 35% at optimal presentation level, which DECREASES to 28% at higher intensities. The performance-intensity curve demonstrates the pattern marked **A** in the diagram. Which of the following is the most appropriate next diagnostic step?
A. High-frequency audiometry beyond 8 kHz to characterize the sloping configuration
B. MRI of the internal auditory canal with gadolinium contrast to exclude vestibular schwannoma
C. Tympanometry and acoustic reflex testing to assess middle ear function
D. Repeat pure-tone audiometry with bone conduction to confirm sensorineural hearing loss
Explanation
Why MRI of the internal auditory canal with gadolinium contrast is correct
The performance-intensity curve marked A shows PB-max <50% with rollover—the hallmark of retrocochlear pathology. The patient's disproportionately poor WRS (35% despite only mild-to-moderate pure-tone loss) combined with the ROLLOVER PHENOMENON (WRS decreasing at higher intensities) is pathognomonic for retrocochlear lesion, most commonly vestibular schwannoma. According to Katz Clinical Audiology 7e, when WRS demonstrates rollover (rollover index >0.40–0.45) or is much worse than pure-tone thresholds predict, MRI IAC with gadolinium is mandatory to visualize the tumor and confirm diagnosis. This finding alone warrants neuroimaging regardless of other test results.
Why each distractor is wrong
Repeat pure-tone audiometry with bone conduction: While bone conduction testing confirms sensorineural hearing loss, it does NOT differentiate cochlear from retrocochlear pathology. The rollover phenomenon on speech audiometry is the critical diagnostic clue; repeating pure-tone testing will not change management or identify the underlying lesion.
Tympanometry and acoustic reflex testing: These tests assess middle ear function and are normal in sensorineural hearing loss. They are not indicated here and do not address the retrocochlear pathology suggested by the speech audiometry pattern.
High-frequency audiometry beyond 8 kHz: Although steeply sloping high-frequency SNHL can produce poor WRS without true retrocochlear disease, the presence of ROLLOVER (WRS decreasing at higher intensities) is a specific indicator of neural dysfunction that cannot be explained by cochlear configuration alone. This patient's rollover mandates imaging, not further frequency-specific testing.
High-YieldNEET PG
Rollover on speech audiometry (WRS decreasing at higher intensities) = retrocochlear pathology until proven otherwise; order MRI IAC with gadolinium.
Katz Clinical Audiology 7e; AAO-HNS guidelines for retrocochlear hearing loss evaluation
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