Neurofibromatosis Type 2 Bilateral Vestibular Schwannomas
medium
ear ENT
A 24-year-old woman presents to the ENT clinic with progressive hearing loss over the past 2 years. Audiometry reveals the pattern marked **A** in the diagram: bilateral high-frequency sensorineural hearing loss with disproportionately poor word recognition despite relatively preserved pure-tone thresholds. MRI with gadolinium shows bilateral enhancing masses at the cerebellopontine angles. Which of the following best explains the disproportionate word recognition deficit observed in this patient's audiological profile?
A. Sensorineural hearing loss from noise exposure with normal speech discrimination scores and symmetric audiometric pattern
B. Conductive hearing loss from ossicular fixation secondary to meningioma involvement of the middle ear
C. Retrocochlear pathology causing neural desynchronization and rollover phenomenon due to vestibular schwannomas compressing CN VIII
D. Cochlear endolymphatic hydrops causing low-frequency fluctuating hearing loss with preserved speech discrimination
Explanation
Why option 1 is correct
The pattern marked A — bilateral high-frequency SNHL with poor word recognition — is the hallmark retrocochlear presentation of neurofibromatosis type 2 (NF2) with bilateral vestibular schwannomas. The disproportionate word recognition deficit (rollover phenomenon) occurs because the schwannomas compress the vestibulocochlear nerve (CN VIII) at the cerebellopontine angle, disrupting neural synchronization and causing desynchronization of auditory nerve firing. This neural desynchronization produces abnormal auditory brainstem responses (wave V delay/absence) and poor speech discrimination despite relatively preserved pure-tone thresholds — a classic retrocochlear pattern. The bilateral presentation confirms NF2 diagnosis, which is an autosomal dominant tumor predisposition syndrome caused by germline NF2 gene mutations on chromosome 22q12.2 (Cummings Otolaryngology, 7th ed.).
Why each distractor is wrong
Option 2: Conductive hearing loss from ossicular fixation would produce a conductive or mixed pattern with air-bone gap on audiometry, not sensorineural loss. Meningiomas in NF2 arise intracranially and do not typically involve the middle ear ossicles. This describes option B (bilateral conductive loss), not the retrocochlear pattern of option A.
Option 3: Endolymphatic hydrops (Ménière disease) causes low-frequency fluctuating SNHL with preserved or near-normal speech discrimination and a characteristic "rising" audiometric pattern. This does not explain the high-frequency loss, poor word recognition, or bilateral symmetric presentation seen in NF2. This describes option C (unilateral low-frequency SNHL with fluctuation).
Option 4: Noise-induced hearing loss produces symmetric high-frequency SNHL but with normal or near-normal speech discrimination scores (cochlear pathology preserves neural synchronization). The disproportionate word recognition deficit is not a feature of noise exposure. This describes option D (symmetric flat loss with normal speech discrimination).
High-YieldNEET PG
NF2 = bilateral acoustic neuromas + retrocochlear pattern (poor word recognition rollover) + cataracts + meningiomas on chromosome 22; distinguish from NF1 (café-au-lait, Lisch nodules, chromosome 17).
Cummings Otolaryngology, 7th ed.; Manchester/Baser diagnostic criteria for NF2; Knudson two-hit hypothesis; MERLIN/schwannomin function on chromosome 22q12.2
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