Acoustic Neuroma (Vestibular Schwannoma), from the CureRays guide library.

An acoustic neuroma is a benign tumor on the hearing-and-balance nerve — many are simply monitored, and when treatment is needed, single-session radiosurgery can control it precisely while protecting hearing and facial movement.

What it is.

An acoustic neuroma — more accurately called a vestibular schwannoma — is a benign (non-cancerous) tumor that grows from the Schwann cells, the cells that form the insulating sheath around the vestibulocochlear nerve, the nerve that carries hearing and balance signals from the inner ear to the brain. It develops in the narrow canal and angle where this nerve passes from the inner ear toward the brainstem. Because it sits on the hearing-and-balance nerve and lies close to the facial nerve (which moves the muscles of the face), its symptoms usually involve those functions: gradual hearing loss in one ear, ringing in that ear (tinnitus), unsteadiness or balance problems, and sometimes facial numbness or, with larger tumors, facial weakness. These tumors are almost always benign and slow-growing, and they do not spread to other parts of the body. Most occur on one side and have no clear cause; a small number occur in people with an inherited condition called neurofibromatosis type 2, which can cause tumors on both sides. Because they grow slowly and many barely grow at all, a very common and reasonable first approach — especially for small tumors with good hearing — is careful monitoring with periodic MRI scans and hearing tests. When treatment is needed, the two main options are surgery and focused radiation, and the choice depends on the tumor's size, the person's hearing, age, and preferences. The central goals of treatment are to control the tumor while preserving hearing and protecting the facial nerve, and modern radiation techniques are very good at doing exactly that for appropriately sized tumors.

How radiation treats it.

Radiation therapy controls an acoustic neuroma by delivering precisely targeted energy that damages the DNA inside the tumor's cells, halting their ability to grow and divide. Because these tumors are benign and slow-growing, success is measured as long-term control — the tumor stops enlarging and frequently shrinks over the following years — rather than a quick disappearance. The technique that makes this possible is stereotactic radiosurgery, in which many radiation beams are aimed from different directions so that they all intersect precisely at the tumor. Each individual beam is weak, but together they deliver a strong, conformal dose right at the target, while the dose falls off so steeply at the edges that the structures packed in around the tumor receive very little. That precision is the whole point here, because the tumor sits within millimeters of the facial nerve, the hearing nerve and cochlea, and the brainstem. Sparing those structures is what allows radiation to control the tumor while protecting facial movement and, in many cases, preserving useful hearing. Treatment is often given in a single session without any incision, and for somewhat larger tumors or for extra protection of hearing, the dose can instead be divided into several smaller sessions (fractionated radiotherapy), giving sensitive tissues time to recover between treatments. Careful planning keeps the dose to the cochlea low, which is linked to a better chance of keeping hearing. For small and medium acoustic neuromas, focused radiation achieves tumor control in roughly 90–95% of cases over the long term, with rates of facial-nerve preservation that are very high, making it an effective alternative to surgery — particularly for tumors that are not large enough to require an operation to relieve pressure on the brainstem.

The ways we can treat it.

Stereotactic radiosurgery (SRS). Many finely aimed beams converge on the tumor to deliver a precise dose in a single session, with the dose dropping off sharply so the nearby facial nerve, brainstem, and cochlea are largely spared — well suited to small and medium tumors.

Fractionated stereotactic radiotherapy (FSRT). The same precise targeting delivered as several smaller daily treatments, used for somewhat larger tumors or to give sensitive structures like the cochlea extra protection in hopes of preserving hearing.

Cochlea-sparing planning. Treatment is planned to keep the radiation dose to the cochlea (the hearing organ) as low as possible, since limiting that dose is linked to a better chance of keeping useful hearing.

Proton therapy in selected cases. Proton beams stop after reaching the target, reducing dose to surrounding brain and structures — an option in selected cases, particularly in younger patients.

Questions we hear often.

Is an acoustic neuroma cancer? No. An acoustic neuroma (vestibular schwannoma) is a benign, non-cancerous tumor, and it does not spread to other parts of the body. The reason it needs attention is its location — it sits on the hearing-and-balance nerve and close to the facial nerve and brainstem, so as it grows it can affect hearing, balance, and facial movement.

Will treatment affect my hearing or my face? Protecting hearing and facial movement is the central goal of treatment. Focused radiation is planned to keep the dose to the hearing organ and facial nerve as low as possible, and facial-nerve preservation rates are very high. Hearing is harder to guarantee with any treatment, but careful, cochlea-sparing radiation gives many people a good chance of keeping useful hearing, especially for smaller tumors.

Should I just watch it instead of treating it? Often, yes — at least at first. Many acoustic neuromas grow very slowly or not at all, so for small tumors, especially with good hearing, doctors frequently recommend active surveillance: a baseline MRI and hearing test, then repeat scans to see whether it changes. Treatment is recommended if the tumor grows or symptoms worsen, which spares people unnecessary treatment for a tumor that may stay stable.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.