Schwannoma

What is schwannoma?

A schwannoma is a slow-growing, usually harmless (benign) tumour that grows from Schwann cells, the cells that insulate your nerves. They are almost always solitary, and it is very rare for them to become cancerous.

The most common locations include:

• Vestibular schwannoma (acoustic neuroma): grows on the nerve used for hearing and balance; commonly causes hearing loss or ringing in one ear.

• Spinal schwannoma: develops on spinal nerve roots and can cause pain, numbness, or weakness if it presses on the spinal cord.

• Peripheral schwannoma: found in the limbs, neck, or torso, usually appearing as a slow-growing lump under the skin.

• Trigeminal schwannoma: affects the facial nerve, potentially causing numbness or jaw weakness.

Unlike other nerve tumours, schwannomas are encapsulated, meaning they sit on top of the nerve rather than being tangled inside it, making them easier to remove surgically if necessary.

Symptoms of schwannoma

Schwannoma symptoms depend entirely on the nerve involved and the size of the tumour. Common signs include:

• Vestibular schwannoma: gradual unilateral hearing loss, tinnitus in one ear, balance problems, and in larger tumours facial numbness or weakness from trigeminal or facial nerve compression

• Spinal schwannoma: radicular pain following a specific nerve distribution, tingling or numbness in the arms or legs, progressive muscle weakness, and in larger tumours spinal cord compression causing myelopathy with gait disturbance and bladder dysfunction

• Peripheral schwannoma: a slowly growing, deep, firm lump that may be tender on direct pressure, with tingling or electric shock-like sensations along the nerve distribution when the mass is pressed, which may produce a positive Tinel's sign

• Trigeminal schwannoma: facial numbness, pain, or difficulty chewing

Many schwannomas cause no symptoms in their early stages and are discovered incidentally on MRI performed for another reason.

What causes schwannoma?

Most schwannomas arise sporadically, without a known inherited cause. They develop when Schwann cells acquire genetic changes that promote abnormal cell growth. Contributing factors include:

• Genetic mutations: sporadic schwannomas commonly contain acquired genetic changes affecting pathways involved in Schwann cell growth, including alterations involving the NF2 gene and its protein product, merlin. These changes occur in the tumour cells and are not necessarily inherited.

• NF2-related schwannomatosis: a rare inherited condition associated with multiple schwannomas, particularly bilateral vestibular schwannomas, as well as other nervous system tumours.

• Other forms of schwannomatosis: several genetic forms of schwannomatosis can cause multiple schwannomas, often affecting peripheral or spinal nerves. Vestibular schwannomas are generally not the defining feature of these conditions.

• Radiation exposure: prior radiation treatment to the head or spine can increase the risk of developing a schwannoma years later.

• Age: they are most commonly diagnosed in adults between the ages of 40 and 60.

How is schwannoma detected?

Schwannomas are detected primarily through MRI, which provides the high-resolution detail needed to see how the tumour relates to the surrounding nerves.

MRI is the gold standard for identifying schwannomas. It can show the tumour's exact size and a well-defined capsule that helps distinguish it from more aggressive growths. Elfcare’s full-body MRI scans the brain (to find hearing-related tumours) and the entire spine (to find tumours on nerve roots). It also images the neck and torso to spot tumours in the peripheral nerves.

Blood tests cannot detect schwannomas directly but are relevant when a genetic syndrome is suspected or when assessing the overall clinical context. Relevant markers in Elfcare's panel include:

• CRP: helps determine if a lump is a schwannoma rather than an infection or inflammatory mass.

• HbA1c and glucose: screens for diabetes-related nerve damage (neuropathy), which can cause symptoms similar to a schwannoma.

• Calcium: checked if multiple tumours are present to rule out specific rare genetic or endocrine syndromes.

• Full blood count: provides a baseline health assessment, which is helpful if surgery is being considered.

Why early detection matters

Schwannomas grow slowly, and the window between a small, easily managed tumour and one causing irreversible nerve damage can span years. A vestibular schwannoma identified when it is small can be treated with stereotactic radiosurgery (Gamma Knife) with excellent hearing preservation rates. The same tumour identified after significant hearing loss has occurred cannot restore the function already lost. A spinal schwannoma causing early radiculopathy can be surgically removed with good nerve preservation. One causing established myelopathy from spinal cord compression may leave permanent neurological deficits even after successful removal. Early detection through MRI before symptoms become significant is the most important determinant of the outcome.

How Elfcare can help

Elfcare's full body MRI covers the brain, entire spine, and neck soft tissues as standard, providing comprehensive imaging of the regions where schwannomas most commonly develop. Vestibular schwannomas, spinal schwannomas, and paraspinal masses are among the incidental findings most meaningful to identify on a full body health check, as they are frequently asymptomatic in early stages yet can cause irreversible neurological damage if growth is unchecked.

For peripheral schwannomas in limb locations, targeted regional MRI is available for dedicated assessment of a specific area of concern.

If our MRI identifies a schwannoma or suspicious nerve sheath tumour, we take care of further diagnostics or refer you to the appropriate specialist.