Describe the cranial nerve testing.
Cochlear nerve (CN VIII): sensorineural hearing loss
Audiometry
Hearing loss with a greater deficit for higher frequencies
Best initial test: > 90% of patients will have some type of hearing loss. [2]
Weber test: lateralization to the normal ear
Rinne test: air conduction > bone conduction in both ears
Brainstem-evoked audiometry: delay in cochlear nerve conduction time on affected side finding
Can be used as an additional test in patients with asymmetric audiometry findings
More cost-effective but less sensitive than an MRI
Trigeminal nerve (CN V): ipsilateral decreased corneal reflex
Facial nerve (CN VII): ipsilateral facial twitching or weakness
What is the imaging modality of choice?
Contrast MRI
Describe the contrast MRI.
Recommended in patients with abnormal audiometric testing or high clinical suspicion of acoustic neuroma (cerebellopontine angle syndrome)
CT with and without contrast is an alternative for those who cannot undergo MRI.
Shows an enhancing lesion by the internal auditory canal, with possible extension into the cerebellopontine angle
What are the histopahtological findings?
Gross findings: encapsulated firm mass
Microscopic findings
Spindle cells in palisades (Antoni A tissue) alternating with myxoid hypocellular areas (Antoni B tissue)
S-100 positive
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