Schwannomas are neural tumors that grow within the nerve sheath. These tumors arise from the schwann cells inside the nerve. Because neural tumors can exist in any nerve throughout the body, their growth varies greatly. Schwannomas are very slow-growing tumors in most cases. However, schwannomas can undergo malignant changes that cause the tumor to grow rapidly and into surrounding tissues, organs and bones. Schwannoma growth is often asymptomatic until it is fairly large, unless it is in a compacted area. A neurologist, oncologist, neurosurgeon or any combination of the three are the most qualified doctors to assess schwannoma growth.
Identification
Some schwannomas, such as those that occur in peripheral nerves, are visible from the outside. Major growth is visible by observing the size externally. This technique is not extremely accurate, since schwannomas can grow inward, and external observation only shows outward growth. Schwannomas that occur in nerves inside the brain, trunk or anywhere deep within the body are only visible via X-ray, computerized tomography (CT), ultrasound or magnetic resonance imaging (MRI) scans. MRI is the scan of choice for measuring schwannomas with extreme detail. Comparing current scans with previous scans reveals any growth between the two.
Features
Schwannomas can grow anywhere in the nervous system, so their development varies greatly. Schwannomas grow in a direction until they meet resistance, and then change direction to continue growing. Most schwannomas that haven't hit a bone, muscle or organ tend to grow in an oval shape, since growing lengthwise in a nerve is not restricted at all, but the nerve sheath does provide some resistance. If a structure blocks the schwannoma, the growth extends sideways. In small places, such as the head, schwannomas can even grow in a barbell shape from surrounding structures restricting growth. Malignant schwannomas extend through the nerve sheath and into nearby organs, tissues or bone.
Considerations
Remember that measuring the growth using two different techniques provides completely different numbers, and is not accurate for comparison. An ultrasound and an MRI scan done at the same time will not match. Discrepancies in these numbers cannot reveal growth because of their different capabilities in measuring the schwannoma.
Effects
When a schwannoma grows, it pushes other nerve fibers outward. Once the fibers press against something, such as bone, muscle or an organ, symptoms appear. Symptoms from schwannomas include numbness, tingling, shooting pains, electric shock sensations, pins and needles and buzzing feelings. As the schwannoma further presses the nerve, these symptoms become more severe, and the affected nerves suffer innervation. This causes muscle atrophy in the areas that depend on the nerve for sensations. Schwannomas can also press against veins or arteries and cause a loss of downward blood flow. Schwannomas pressing on organs can cause dysfunction in the organs affected.
Prevention/Solution
Radiation is effective at stopping growth, and can sometimes reverse it. Specifically, Gamma Knife and reflected solar radiation are common choices when treating schwannoma growth. The only solution to schwannoma growth is surgical removal. The neurosurgeon opens the nerve sheath and carefully cuts the schwannoma out of the nerves. It is rare to remove the entire schwannoma, and there is a possibility that it will return. Removing a malignant schwannoma growth is much more complicated, since doctors aim to remove all diseased areas, even those outside the nerve.
Considerations
Schwannomas that undergo rapid growth warrant a new MRI scan and full assessment by a physician. Rapid growth is often one of the first signs of malignant transformation.
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