A 52-year-old woman presents with 2 years of progressive unilateral right-sided hearing loss, high-pitched tinnitus, and recent right-sided facial numbness in the V1-V2 distributions. Pure-tone audiometry shows right-sided high-frequency sensorineural hearing loss with disproportionate drop in speech discrimination at louder intensities (roll-over phenomenon). BAER reveals prolonged Wave I-III interval on the right. MRI brain with internal auditory canal protocol is performed. The structure marked **A** in the diagram—a T2-hyperintense mass in the right cerebellopontine angle—is noted to be avidly enhancing on gadolinium. Based on the clinical presentation and imaging findings, what is the most likely diagnosis?
A. Right meningioma of the cerebellopontine angle with compression of cranial nerves V and VIII
B. Right vestibular schwannoma (acoustic neuroma) with retrocochlear pathology and trigeminal nerve involvement
C. Right cerebellar hemangioblastoma with mass effect on the vestibulocochlear nerve
D. Right facial nerve schwannoma with secondary sensorineural hearing loss
Explanation
Why Option 1 is correct
The clinical presentation of progressive unilateral sensorineural hearing loss with roll-over phenomenon, prolonged Wave I-III interval on BAER (indicating retrocochlear pathology), and early trigeminal nerve involvement (absent corneal reflex, V1-V2 sensory loss) is pathognomonic for vestibular schwannoma. The T2-hyperintense, avidly enhancing mass marked A in the cerebellopontine angle is the characteristic imaging appearance of acoustic neuroma. The combination of eighth nerve dysfunction (hearing loss, positive Romberg) and fifth nerve involvement (facial numbness) reflects the anatomical location and mass effect of this tumor. According to Goldbrunner et al. (EANO guideline), vestibular schwannoma is the most common tumor of the cerebellopontine angle and the diagnosis of choice in adults presenting with asymmetric sensorineural hearing loss until proven otherwise.
Why each distractor is wrong
Option 2 (Facial nerve schwannoma): While facial nerve schwannomas can occur in the CPA, they typically present with progressive facial weakness (House-Brackmann grade ≥II), which this patient does not have (HB Grade I with normal facial function). Facial schwannomas are also less common than vestibular schwannomas and do not typically cause the characteristic retrocochlear hearing loss pattern with roll-over phenomenon and prolonged Wave I-III interval.
Option 3 (Cerebellar hemangioblastoma): Hemangioblastomas are typically hypervascular lesions that show prominent flow voids on MRI and are associated with von Hippel-Lindau syndrome. They do not characteristically present with the insidious progressive sensorineural hearing loss and retrocochlear BAER findings seen in this patient. The clinical syndrome of progressive hearing loss with trigeminal involvement is not typical of hemangioblastoma.
Option 4 (Meningioma of CPA): Although meningiomas can occur in the cerebellopontine angle and may compress cranial nerves V and VIII, they typically show dural attachment, broader dural base, and different enhancement patterns. Meningiomas are less likely to produce the characteristic retrocochlear hearing loss pattern with roll-over phenomenon and prolonged Wave I-III interval. The clinical presentation with progressive high-frequency sensorineural hearing loss is more typical of vestibular schwannoma.
High-YieldNEET PG
Vestibular schwannoma (acoustic neuroma) is the diagnosis of choice in any adult with asymmetric sensorineural hearing loss; the combination of retrocochlear BAER findings (prolonged Wave I-III interval), roll-over phenomenon on audiometry, and a T2-hyperintense, avidly enhancing CPA mass is diagnostic.
Goldbrunner R et al. EANO guideline on the diagnosis and treatment of vestibular schwannoma. Neuro Oncol 2020;22(1):31-45.
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