A vestibular schwannoma (acoustic neuroma), is a non-cancerous (benign) tumor that develops along the main balance and hearing nerve leading from your inner ear to your brain.
When the tumor puts pressure on the nerve, a person can experience hearing loss, dizziness, loss of balance and ringing in the ear (tinnitus).
As the tumor grows, it can also put pressure on the nerves affecting sensations and muscle movement in the face.
Gamma knife surgery may stop the growth or minimize the size of a vestibular schwannoma with little risk of permanent nerve damage.
What are the causes of Vestibular Schwannoma?
A malfunction in a gene on chromosome 22 has been found to cause vestibular schwannomas. This gene generally makes a protein that controls the growth of Schwann cells covering the nerve. Some of the risk factors make it more prone that people can develop a vestibular schwannoma:
- People with a genetic syndrome called neurofibromatosis type 2 (NF 2) are more likely to develop schwannomas.
- NF 2 patients will often develop vestibular schwannoma on both sides, or on other nerves.
- Prolonged exposure to loud noise
- Prior radiation therapy to the head and neck area during childhood
What are the symptoms of Vestibular Schwannoma?
Symptoms generally arise as the schwannoma grows large enough to put pressure on the nerves that control hearing, or the surrounding brain. The most common symptoms of vestibular schwannomas are:
- Hearing loss - This usually happens slowly over years, so a patient may not even be aware of the hearing loss. This is most commonly just on one side.
- Tinnitus, a ringing sound in the affected ear
- Balance problems or a feeling of leaning to one side
- Numbness, pain or weakness of the facial muscles
What are the treatment options for Vestibular Schwannoma?
There are many ways to treat vestibular schwannomas including observation, surgery or radiation therapy. The aim of treatment is lower down the symptoms, while preserving the function of the nerve.
Usually, active treatment will be advised if the schwannoma is causing significant symptoms, or if it is found to be growing rapidly. Active treatment is more likely to be advised if the patient is young or the schwannoma is particularly large.
Most vestibular schwannomas are slow growing and may not cause a patient any significant problems over their lifetime.
If the tumor is small, a “wait and watch” approach can be recommended with repeat imaging (usually MRI scans every 6 to 12 months) and hearing tests, rather than treating the schwannoma straight away.
If during observation there is rapid growth, evidence of hearing loss or development of new symptoms, then active treatment should be considered.
Removing the schwannoma with surgery can stop symptoms getting any worse by relieving pressure on the nerve. This may involve accessing the tumor through the inner ear, or through an incision through the skull.
If the schwannoma is completely removed it is very unlikely to grow back, however there is a risk of damaging nerves during surgery, which could cause further hearing loss or damage to the nerve controlling the facial muscles. Some patients may also experience headaches following surgery.
If the tumor is located too close to important nerves or blood vessels it may not be able to be completely resected. If residual tumor is left behind, then this can re-grow following surgery in approximately 15% of patients.