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Schwannoma is sometimes known as neurilemmomas or neuromas, is a tumor that arises from Schwann cells in the peripheral nervous system or nerve roots. Schwannomas are most found in the nerve that connects the brain to the inner ear, also known as vestibular schwannoma. Schwannomas are often slow growing.
Schwann cells aid in the transmission of nerve impulses. They protect and maintain peripheral nerves by wrapping around them. A schwannoma is a tumor that develops from a single bundle or fascicle within the main nerve and displaces the remainder of the nerve. When a schwannoma grows, it affects more fascicles, making eradication more difficult.
Schwannomas can arise at any age and in any part of the body. Although they are rarely malignant, they can cause nerve damage and muscular weakness. Cancerous schwannomas most commonly damage the sciatic nerve in the leg, the brachial plexus nerves in the arm, and the sacral plexus nerve group in the lower part of the back. If one happens to notice any strange lumps or numbness, consult a medical professional.
Symptoms
The signs and symptoms of schwannomas can go undetected for years. The severity and frequency of symptoms may vary among individuals. The manifestation of symptoms changes significantly as these tumors have slow growth and can develop in various parts of the body. For instance:
- Sciatic nerve schwannomas can cause low back pain that radiates down the leg.
- Tumors of the facial nerve can interfere with eating, eye movement, and taste sensations, as well as induce facial paralysis.
- Vestibular schwannomas can cause hearing and balance problems, as well as ringing sensations or tinnitus.
Generally, common signs and symptoms of a schwannoma include:
- Paresthesia, characterized by a pins–and–needles sensation.
- The presence of a visible lump that may be tender when pressure is applied.
- Numbness.
- Muscles weakness.
- Aching, burning, or stabbing pain.
If any of the signs and symptoms persist, consult a healthcare provider for proper diagnosis and treatment. In cases where the doctor recommends monitoring the tumor instead of pursuing treatment, it is necessary to schedule regular visits, at least once a year. Imaging tests will be required to monitor the growth and status of the tumor.
Those who have schwannoma and experience new or worse symptoms, it is important to consult the healthcare provider for guidance on how to handle the changes in the condition.
Causes
Studies on genetics have revealed that the NF2 gene located on chromosome 22 plays a crucial role in the formation of schwannomas. Certain genetic disorders such as Carney complex, neurofibromatosis 2 (NF2), and schwannomatosis have been linked to the development of schwannomas. However, about 90% of occurrences are considered sporadic, meaning they arise randomly without a known cause. The exact cause of this condition is still unknown.
Diagnosis
Since schwannomas grow slowly, it may take several years before being discovered. In some cases, it may be discovered by chance while analyzing imaging test findings for another medical reason.
If one is suffering symptoms, the doctor will most likely prescribe imaging testing and other diagnostic tests, such as:
- Physical examination: Healthcare provider diagnosis of schwannoma often requires discussing the signs and symptoms, assessment of family and personal medical history, and conducting a physical and neurological examination.
- Magnetic resonance imaging (MRI): This is the most frequently used imaging test for detecting and diagnosing schwannomas. An MRI is a painless test that uses a powerful magnet, radio waves, and a computer to produce comprehensive images of the organs and structures within the body.
- Computerized tomography (CT): A CT scan produces images of the structures inside the body using X–rays and computers. A computer utilizes the photos to create a precise picture of the growth, allowing the doctor to assess how it is affecting patients.
- Ultrasound: Ultrasound can be used by doctors to detect schwannomas beneath the skin. This is a medical imaging technique that uses high–frequency sound waves to create real–time images or films of internal organs or other soft tissues.
- Electromyogram (EMG): This test monitors the electrical signals produced by the muscles while patients attempt to move them. During the procedure, tiny needles are inserted into the muscles allowing an electromyography device to record.
- Nerve conduction study: It assesses the speed with which the nerves transmit electrical messages to the muscles. This test is commonly performed alongside an EMG.
- Tumor biopsy: A biopsy may also be performed to determine whether the tumor is schwannoma. Depending on the size and location of the tumor, one may require local or general anesthetic for the biopsy. During the test, a needle is used to extract a tiny sample from the tumor. A pathologist will examine cells from the sample under a microscope and perform other tests to determine the type of tumor.
- Nerve biopsy: A nerve biopsy may be performed when one has a condition such as progressive peripheral neuropathy or swollen nerves that mimic nerve tumors.
Treatment
There are several treatment options for schwannoma which may include observing the tumor, surgically removing it, or therapy. The best treatment plan is determined by where the tumor is in the body and how fast it is progressing.
- Observation or watch–and–wait: If the tumor is benign, developing slowly, and has no or very minor symptoms, the doctor may advise closely watching it rather than treating it. Regular checks and a CT or MRI scan every few months to see if the tumor is growing may be part of the observation. If it becomes larger and/or produces symptoms, they will most likely recommend medical treatment.
- Surgery: If the tumor is developing rapidly or causing other difficulties, surgical removal may be advised. General anesthesia is used during schwannoma surgery. While the goal is normally to remove the tumor completely, the surgeon may only be able to remove a portion of it. Because schwannomas originate in the sheath surrounding the nerve, surgery can generally be performed without causing any nerve injury. A tumor may reappear even after it has been successfully removed after surgery. Surgery for vestibular schwannomas frequently results in hearing loss.
- Radiation therapy: This may be recommended in tandem with surgery. Radiation therapy is used to control tumor growth and alleviate symptoms.
- Stereotactic radiosurgery: To kill malignancies, stereotactic radiosurgery (SRS) employs many carefully focused radiation beams to accurately deliver radiotherapy to a tumor without requiring an incision. If the tumor is close to essential blood vessels or nerves, the doctor may use SRS instead of surgery to avoid complications which help protect healthy tissue.
