Definition and Overview

Neurilemmomas are tumours that grow on the sheath that protects the nerves. The condition is also known as schwannoma. This is because it starts from Schwann cells, which play an important role in nerve regeneration.

The majority of these growths are benign or non-cancerous. This means that they do not spread to other parts of the body. Thus, they are rarely dangerous. Many of them are very small and grow slowly. Thus, they often do not produce symptoms. Because of this, many patients do not seek treatment and remain undiagnosed. This is often not a problem because it is very rare for the tumour to become cancerous. If they do, they are called soft tissue sarcomas.

This type of tumour can develop in different parts of the body. These include the face, legs, arms, and torso. However, the nerve that connects the inner ear and brain is the most susceptible. Called acoustic neuroma, it can cause deafness and problems with balance. The tumour can also damage the cochlear nerve.

It is important to determine if the tumours are benign or malignant because they are treated differently. While both can be removed with surgery, patients with malignant tumours also often require radiation therapy or chemotherapy.

Causes of Condition

Neurilemmomas can be caused by the following disorders:

  • Schwannomatosis - This is a rare genetic disorder that causes tumours to grow on peripheral nerves located in different parts of the body. It causes severe pain and neurological dysfunction.

  • Neurofibromatosis Type 2 - This disorder causes tumours to grow in the nervous system. It increases the risk of meningioma and vestibular schwannomas.

Other possible causes are certain genetic disorders and exposure to radiation. In some cases, the cause is unknown.

Key Symptoms

Small neurilemmomas often do not cause symptoms. But big ones can put pressure on nearby nerves. This can cause numbness and muscle weakness in the affected body part. Sharp or burning pain is also common. These symptoms can get worse if the tumour continues to grow.

Depending on the location of the tumour, patients may develop more symptoms. For example, tumours within the spinal canal can compress the spinal cord. This can lead to stiffness, incontinence, and even paralysis. Tumours on the eighth cranial nerve can cause hearing loss, tinnitus, and problems with balance.

Who to See and Types of Treatments Available

Patients with symptoms listed above need to undergo standard tests to get a diagnosis. These include a physical exam and review of their medical history and symptoms. Doctors also often order urine and blood tests. These can help them assess the patient’s overall health condition.

If the results of the above tests suggest an abnormality, doctors will order imaging tests. These include x-rays and ultrasound. If the doctor needs more detailed information, he or she will also order magnetic resonance imaging (MRI) and computed tomography (CT) scans. These tests provide clear images of the nerves throughout the body. They can confirm the presence of abnormal growths. Doctors also perform a biopsy in which they obtain tissue samples from the tumour for further study. This test is used to determine if the growth is benign or malignant. The same tests can be used to determine the stage of cancerous growths. Neurilemmomas are classified as grade 1, 2, or 3. Grade 1 tumours are inactive while grade 2 tumours often cause deformity to surrounding tissues. However, they are often not aggressive. Grade 3 tumours, on the other hand, are often locally aggressive but are unlikely to spread to other parts of the body.

The tumours are often removed with surgery. Surgeons must ensure that the procedure will not cause damage to nearby nerves. Damage to nerves can cause permanent problems. This causes them to lose their ability to send or receive signals to and from the brain. This prevents them from performing their normal function.

In cases where the tumour is small, doctors may advise active surveillance. This means that no treatment is provided but the tumour is observed for any changes. The patient’s condition is monitored through periodic MRI scans.

Cancerous tumours are also removed through surgery. To make sure that no cancer cells remain, the patient will also undergo radiotherapy. This treatment sends strong doses of radiation directly to the tumour. It works by breaking up the DNA of cancer cells to stop them from growing and dividing. In many cases, patients need multiple sessions to ensure that all cancer cells are destroyed.

Surgery often provides rapid and complete symptom relief. It also provides excellent long-term results. It is highly unlikely for tumours to recur after they were removed. Many patients with acoustic neuroma are able to preserve their hearing following treatment.


  • Ichinose T, Takami T, Yamamoto N, Tsuyuguchi N, Ohata K. Intratumoral hemorrhage of spinal schwannoma of the cauda equina manifesting as acute paraparesis–case report. Neurol Med Chir (Tokyo). 2009 Jun. 49(6):255-7.

  • Roche PH, Bouvier C, Chinot O, Figarella-Branger D. Genesis and biology of vestibular schwannomas. Prog Neurol Surg. 2008. 21:24-31.

  • Rutten I, Baumert BG, Seidel L, et al. Long-term follow-up reveals low toxicity of radiosurgery for vestibular schwannoma. Radiother Oncol. 2007 Jan. 82(1):83-9.

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