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Vestibular schwannoma (acoustic neuroma)
Vestibular schwannoma is a benign tumour of Schwann cells of the vestibular nerve, presenting with asymmetric sensorineural hearing loss and one-sided tinnitus; MRI with gadolinium diagnoses it, and the choice between observation, radiosurgery and surgery depends on size, growth, hearing and age.
Why it matters in the exam
It is the commonest tumour of the cerebellopontine angle (about 80% to 90% of tumours there). The exam shows an adult with one-sided or asymmetric hearing loss, tinnitus and mild unsteadiness; with a large tumour — loss of the corneal reflex (nerve V is affected before nerve VII), facial numbness, and with a very large tumour — hydrocephalus. The facial nerve is resilient and affected late. Every asymmetric sensorineural loss or one-sided tinnitus requires MRI with gadolinium of the internal auditory canal.
On MRI the tumour enhances, fills the internal auditory canal and protrudes into the angle in an "ice-cream cone" shape. Meningioma differs by a broad dural base, a "dural tail" and calcification, and usually does not enter deep into the canal. Bilateral schwannomas are the hallmark of NF2 (now NF2-related schwannomatosis), with a mutation on chromosome 22; there bevacizumab can also slow growth and preserve hearing.
A small tumour without growth suits MRI follow-up ("wait and scan") — about half of tumours do not grow. Stereotactic radiosurgery suits a small to medium tumour (up to about 3 cm) that grows. Surgical approaches: translabyrinthine — does not preserve hearing, suits any size; retrosigmoid — allows hearing preservation and suits large tumours; middle cranial fossa — for a small intracanalicular tumour with good hearing. Complications: facial palsy, hearing loss, CSF leak and headache. The decision is shared with the patient: an older adult with a small tumour and good hearing will often choose observation, while a young patient with a growing tumour leans toward active treatment. For each option the chance of preserving hearing and facial nerve function is explained in advance.
Key points
- Benign Schwann cell tumour of the vestibular nerve.
- Asymmetric loss and one-sided tinnitus.
- MRI with gadolinium.
- Observation, radiosurgery or surgery.
- Bilateral — NF2.
Summary table
| Situation | Approach | Note |
|---|---|---|
| Small tumour, not growing | MRI follow-up | About half do not grow |
| Small to medium and growing | Radiosurgery | Up to about 3 cm |
| Growing intracanalicular tumour with good hearing | Middle cranial fossa | Hearing preservation |
| Large tumour | Retrosigmoid or translabyrinthine | Brainstem compression |
| No useful hearing | Translabyrinthine | Does not preserve hearing |
| NF2 | Multidisciplinary team, bevacizumab | Bilateral schwannomas |
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Sources
- Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on the Management of Patients With Vestibular Schwannomas, 2018 — Observation, radiosurgery and surgery
- EANO guideline on the diagnosis and treatment of vestibular schwannoma, 2020 — Management by size and hearing
- Cummings Otolaryngology: Head and Neck Surgery, 7th edition (2021) — Tumours of the internal auditory canal and cerebellopontine angle
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.