A schwannoma is a tumour of the tissue that covers nerves, called the nerve sheath.
What is a schwannoma?
A schwannoma (sh-won-oma) is a tumour of the tissue that covers nerves, called the nerve sheath. These tumours develop from a type of cell called a Schwann cell, which gives them their name.
Schwannomas are often not cancerous (benign).
The most common type of schwannoma is a vestibular schwannoma. It affects the nerve responsible for balance (also called the vestibular nerve).
It can cause inner ear deafness because the hearing and balance nerve run together, and as the tumour grows it damages the hearing nerve (cochlear nerve). Because of this doctors used to call them acoustic neuromas.
When these tumours are cancerous they are called malignant schwannomas. They are also called malignant peripheral nerve sheath tumours or neurofibrosarcomas.
They can start anywhere in the body.
The most common areas are:
- the major nerve of the leg (the sciatic nerve)
- the nerves at the top of the arm (the brachial plexus)
- the lower back (the network of nerves called the sacral plexus).
Tests to diagnose schwannoma
Your doctor will examine you and you might have blood tests to check your general health. Other tests might include:
- MRI scan
- hearing test
Treatment of Schwannomas
Treatment depends on where the tumour is in your body and whether it is benign or malignant (cancerous). Your specialist may monitor you carefully at first rather than suggest treatment. They will see your regularly and monitor any symptoms you have. This is because the treatment can cause a lot of side effects.
The main treatment for schwannoma is surgery to remove the tumour. The type of surgery you have depends on where in the body the tumour is.
You might also have radiotherapy and chemotherapy if you have a malignant tumour.
Neurofibromatosis Type 2 and Schwannomatosis
Neurofibromatosis Type 2 (NF2) is a rare inherited condition which can make you more likely to develop vestibular schwannomas in both ears. It can also increase your risk of developing a tumour in the lining of the brain and spinal cord, called a meningioma.
Symptoms can include:
- hearing loss, that gradually gets worse over time
- ringing or buzzing in the ears (tinnitus)
- problems with balance
Another rarer condition associated with schwannomas is schwannomatosis. People with schwannomatosis develop multiple schwannomas on the nerves throughout the body, including in their:
Pain at the site of the tumour is common with schwannomatosis. People with schwannomatosis do not usually develop the other tumour types seen in NF2 (such as meningioma).
Treatment of NF2 and Schwannomatosis
Surgery is usually only done if the tumour is causing symptoms or you are feeling very unwell. This is because surgery can cause other problems.
Very occasionally if the tumours are growing they may be treated with radiotherapy. However there is a risk with radiotherapy that the tumour might regrow or change and become malignant (cancerous).
Your specialist will discuss the risks of any treatment with you.