Acoustic neuroma (vestibular schwannoma) most commonly arises from which part of the vestibulocochlear nerve?

• A Cochlear division — spiral ganglion
• B Cochlear division — organ of Corti
• C Superior or inferior vestibular division — Scarpa's ganglion, at the glial-Schwann cell junction (Obersteiner-Redlich zone) ✓
• D Entire CN VIII at the brainstem exit zone

Explanation

Acoustic neuromas (more accurately vestibular schwannomas, as 95% arise from the vestibular division, not the cochlear nerve) originate at the Obersteiner-Redlich zone — the transition point between central (glial) and peripheral (Schwann cell) myelin, located within the internal auditory canal near its fundus. They arise from the inferior vestibular nerve slightly more commonly than the superior division. This origin explains why they are usually within the IAC initially and cause vestibular symptoms (imbalance) before pronounced hearing loss.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.