Question

Vestibular schwannoma (acoustic neuroma) arises most frequently from:

• A. Superior vestibular nerve
• B. Inferior vestibular nerve
• C. Cochlear nerve
• D. Facial nerve

Hint:

It is a vestibular schwannoma, and the upper vestibular division is the classic site of origin.

Answer 1

The Correct Option is A

Step 1: A vestibular schwannoma is a benign tumour of the Schwann cells that sheathe the eighth cranial nerve. It typically begins within the internal auditory canal and grows toward the cerebellopontine angle.
Step 2: The eighth nerve has a cochlear division and two vestibular divisions, the superior and inferior vestibular nerves. The tumour almost always starts on the vestibular part, which is why acoustic neuroma is more correctly called vestibular schwannoma.
Step 3: Among the vestibular divisions, the superior vestibular nerve is the classic and most frequently reported site of origin. The transition zone between central and peripheral myelin (Obersteiner-Redlich zone) lies near here, where Schwann cells are most prone to tumour formation.
Step 4: So option A is correct. Although early symptoms are auditory (hearing loss, tinnitus) due to pressure on the adjacent cochlear nerve, the origin is vestibular, not cochlear, so option C is wrong.
Step 5: The inferior vestibular nerve (B) is the next most common site but less frequent than the superior. The facial nerve (D) is displaced by the tumour but is not the usual origin.
Hence the answer is Option A: Superior vestibular nerve.