What are Schwannomas?

By albert

Reviewed: Dr. Mera

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Schwannomas, also called neuromas or neurilemomas, are tumors that affect the Schwann cells. These are cells that form a sheath around nerves to provide support and protection so that the nerves can function normally (i.e. conduct nervous impulses). Schwannomas are most common in people aged between 20 and 50 years. They can affect the cranial nerves, peripheral nervous system (nerve roots), but don’t affect the central nervous system comprising of the brain and the spinal cord.

The nerve connecting the inner ear to the brain is a common site for schwannomas, in which case the condition is known as acoustic neuroma or vestibular schwannoma. Most schwannomas are benign or non-cancerous. However, in a very small percentage of the isolated growths, malignant change can occur. These changes most commonly occur in patients with an underlying diagnosis of neurofibromatosis. Cancerous schwannomas are classified as soft tissue sarcomas. A sarcoma is a type of tumor that involves soft tissues (i.e. muscle, nerves, tendons, deep skin tissue).

1. Symptoms of Schwannomas

It takes quite some time before any symptoms of schwannomas can appear. Usually, there is an average of five years between the onset of symptoms and diagnosis. This is because, while schwannomas form around nerves, their effects only begin when they have grown large enough to put pressure on the nerves sheathed by the affected tissues. By this time, the tumors may be large enough to form visible bumps under the skin on the face, limbs, and the torso. The schwannomas may also cause pain, pins and needles sensations, numbness, and muscle pain in the body parts served by the affected nerves. Schwannomas commonly involve the spinal nerve roots, which means that they can mimic symptoms of a herniated disk of the spine. Lesions can also affect the sciatic nerve and cause low-back pain. Also, in the extremities, they can be asymptomatic or when there is pressure on the nerve, patients can experience mild pain and tingling or numbness in the area. Finally, if these lesions occur in specific compartments of the wrist or ankle, patients can present with carpal tunnel or tarsal tunnel syndrome. In contrast, acoustic neuromas can grow around the auditory vestibular nerve that connects the inner ear to the brain. Symptoms of such tumors include hearing loss, poor balance and coordination, and ringing in the ears (tinnitus).