What is a schwannoma?
A schwannoma is a tumor that develops from the Schwann cells in the peripheral nervous system or cranial nerves. Schwann cells assist conduction of nerve impulses. This type of tumor is usually benign. Schwannomas are sometimes called neurilemomas, neurolemomas, or neuromas. If a schwannoma is malignant (cancer), it may be referred to as a soft tissue sarcoma.
Where are schwannomas typically found?
Schwannomas can be found in the sheath that covers the nerves. They are found in the peripheral nervous system, cranial nerves or the root of a nerve and not in the brain or spinal cord.
A common area for schwannomas is the nerve connecting the brain to the inner ear. This type is called a vestibular schwannoma or an acoustic neuroma.
Cancerous schwannomas most frequently affect the sciatic nerve of the leg, the brachial plexus nerves in the arm, and the group of nerves in the lower back called the sacral plexus.
What are the symptoms of schwannomas?
Symptoms usually appear when they have grown to the point where they are putting pressure on the nerves near them. Symptoms will vary and are tied to the location of the tumor. Symptoms can include:
- A visible lump
- Muscle weakness
- Pins-and-needles feeling
- Night-time back or neck pain
- Pains that are aching, burning or sharp
Schwannomas near the ear can affect hearing, balance, or cause ringing sensations (tinnitus).
Tumors by the facial nerve can affect swallowing, eye movement, and taste sensations or cause facial paralysis.
In some cases, schwannomas cause no symptoms.
What are the causes of schwannomas?
The cause of schwannomas is not known in most cases. Most often they occur spontaneously. Genetic disorders such as Carney complex, neurofibromatosis 2 (NF2) and schwannomatosis can cause schwannomas.
Who is at risk for developing schwannomas?
Schwannomas can occur at any age. However, diagnoses peak between the ages of 20-50 years. There is no difference between the sexes in terms of incidence of schwannomas. However, women are slightly more likely to develop a schwannoma due to NF2.
There is no difference in the incidence based on ethnic or racial backgrounds. A parent with a genetic disorder causing schwannomas can pass the disorder on to their children.