A 50-year-old presents with hearing loss, tinnitus, and cerebellar symptoms. MRI with gadolinium shows an enhancing lesion at the fundus of the internal auditory canal extending into the cerebellopontine angle. The most common histological origin of acoustic neuroma (vestibular schwannoma) is from which specific cell type and which part of CN VIII?
- A Oligodendrocytes of the superior vestibular nerve
- B Fibrocytes of the cochlear nerve
- C Schwann cells of the cochlear nerve at the spiral ganglion
- D Schwann cells of the inferior vestibular nerve at the Obersteiner-Redlich zone ✓
Explanation
Vestibular schwannomas arise from Schwann cells at the Obersteiner-Redlich zone — the junction between the central (oligodendrocyte-covered) and peripheral (Schwann cell-covered) myelin, located within the internal auditory canal 8–12 mm from the brainstem. The inferior vestibular nerve is the most common origin (60–65%) because its Obersteiner-Redlich zone is closest to the cochlea. Superior vestibular nerve origin accounts for ~25%, and cochlear nerve origin is rare. The cochlear nerve has its Obersteiner-Redlich zone near the modiolus, distal from the IAC fundus. NF2-associated tumors are bilateral vestibular schwannomas.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.