What it is
An acoustic neuroma — more precisely called a vestibular schwannoma — is a benign tumor that grows from the Schwann cells lining the vestibular nerve, one of the two components of the eighth cranial nerve. It does not invade brain tissue but can compress the brainstem and nearby nerves as it enlarges.
Most acoustic neuromas grow very slowly. Some barely move on serial imaging over years. Others expand steadily and cause progressive hearing loss, balance problems, or — as they grow larger — facial numbness from compression of the fifth cranial nerve.
How management is decided
The right plan depends on several factors: tumor size, rate of growth, current symptoms, age and overall health, and the patient's own priorities around hearing preservation, risk tolerance, and recovery.
- Observation is appropriate for small tumors discovered incidentally, particularly in older patients or those with limited symptoms. Serial MRI at 6–12 month intervals tracks behavior over time.
- Stereotactic radiosurgery (Gamma Knife, CyberKnife) delivers precisely focused radiation to control tumor growth. It is well-suited for tumors under approximately 3 cm without significant brainstem compression. It does not remove the tumor but typically arrests growth.
- Microsurgical resection is considered when the tumor is large, causing brainstem compression, growing despite radiosurgery, or when the clinical situation makes surgery the most appropriate tool.
Surgical approach
When surgery is chosen, the approach — retrosigmoid, translabyrinthine, or middle fossa — depends on tumor size, residual hearing worth preserving, and surgeon experience. Facial nerve preservation is a central objective of the operation, and intraoperative facial nerve monitoring is used routinely.
What to expect
A multidisciplinary evaluation involving neurosurgery, neurotology, and often radiation oncology gives patients the full picture before any decision is made. Many patients who undergo observation never need intervention. For those who do, outcomes in experienced hands — for both radiosurgery and microsurgery — are generally very good.