A 52-year-old man presents with a 3-year history of progressive hearing loss in the right ear. Audiometry shows the pattern marked **A** in the diagram — asymmetric high-frequency sensorineural hearing loss with disproportionately poor speech discrimination (rollover on PI-PB testing) compared to pure-tone thresholds. He also reports unilateral right-sided tinnitus and mild imbalance. Which of the following is the most likely diagnosis?
A. Occupational noise-induced hearing loss with 4 kHz notch
B. Sudden idiopathic sensorineural hearing loss with flat audiometric pattern
C. Vestibular schwannoma (acoustic neuroma) of the right internal auditory canal
D. Bilateral age-related presbycusis with asymmetric progression
Explanation
Why Vestibular schwannoma (acoustic neuroma) is right
The pattern marked A — asymmetric high-frequency SNHL with disproportionately poor speech discrimination relative to pure-tone thresholds (rollover on PI-PB function) — is the classic audiometric hallmark of vestibular schwannoma. This benign slow-growing tumor arises from Schwann cells of the vestibular division of CN VIII, typically the superior vestibular nerve. The insidious onset over years, unilateral tinnitus, and imbalance complete the classic triad. According to Cummings Otolaryngology 7e, asymmetric SNHL >15 dB at any frequency between ears is a red flag mandating MRI, and the disproportionate speech discrimination loss (rollover) is pathognomonic for retrocochlear pathology such as vestibular schwannoma. The tumor accounts for >90% of cerebellopontine angle lesions and ~8% of intracranial tumors.
Why each distractor is wrong
Bilateral age-related presbycusis with asymmetric progression: Presbycusis (marked B) is bilateral and symmetric by definition, with gradual high-frequency loss in both ears. The marked asymmetry and rollover phenomenon are not features of presbycusis. The 3-year timeline and unilateral tinnitus argue against age-related hearing loss.
Occupational noise-induced hearing loss with 4 kHz notch: Noise-induced hearing loss (marked C) classically presents with a characteristic 4 kHz notch and is typically bilateral and symmetric. It does not cause rollover on speech discrimination testing and lacks the retrocochlear features (poor speech discrimination disproportionate to pure-tone loss) seen in vestibular schwannoma.
Sudden idiopathic sensorineural hearing loss with flat audiometric pattern: Sudden SNHL (marked D) presents acutely (days to weeks) with a flat or low-frequency pattern, not the insidious 3-year course with high-frequency loss and rollover described here. The clinical timeline and audiometric pattern are inconsistent with sudden SNHL.
High-YieldNEET PG
Asymmetric SNHL + rollover on speech discrimination = retrocochlear pathology (vestibular schwannoma) until proven otherwise; MRI brain with gadolinium is the gold standard diagnostic test.
