Description, Causes and Risk Factors:

Alternative Name: Neurilemoma, neuroschwannoma.

Neurilemomas or schwannomas, derive from the Schwann cells of nerve sheaths, and may occur singly or multiply on any nerve or nerve root. The most common location is in fact the acoustic nerve, making this a frequent intracranial tumour. Neurilemomas are almost always benign, very infrequently malignant and should then be called neurogenic sarcomas. However, even benign lesions may recur after incomplete removal. Neurilemomas generally appear in middle adult life but sometimes are encountered earlier, particularly in association with von Recklinghausen's neurofibromatosis. This hereditary syndrome is characterized by multiple nerve tumours, either neurofibromas or neurilemomas. Histologically two patterns, so called Antoni A and Antoni B are encountered in neurilemomas. The Antoni A pattern comprises interlacing bundles or whorls of elongated spindle cells, and the Antoni B pattern a very loose, disorganized myxoid tissue with abundant ground substance and scattered stellate cells.

Types may include: Acoustic schwannoma, vestibular schwannoma, and spinal schwannoma.

The causes of this type of tumor are mainly unknown. However, the consensus among brain tumor specialists is that they may be caused by some hereditary defect. Schwannoma tumors usually appear in conjunction with a genetically inherited condition known as neurofibromatosis (NF) especially in those patients that have a specific type of NF (neurofibromatosis type II).

Schwannomas are being subjected to a great deal of scrutiny by the medical profession and the general public because of reports that electromagnetic or radiofrequency radiation from cell phones may be a significant risk factor for people who develop a special type of schwannoma called vestibular schwannoma or acoustic neuroma (essentially a schwannoma of the acoustic nerve).

Data is inconclusive and much debate still exists. However, it has been proposed that a saturation level of these electromagnetic and radiofrequency radiations have been reached and may be causing many types of diseases including different types of brain tumors.


Schwannomas are extremely slow-growing tumors. It usually takes years before they cause any symptoms, and they build so gradually that schwannomas are large by the time a doctor gets involved.Smaller schwannomas may cause numbness, tingling, pins-and-needles sensations and electric-shock feelings. As they grow, they are more likely to cause pain and progressive numbness. The symptoms of nerve dysfunction, such as pins-and-needles, electric-shock sensations and tingling get worse as the tumor grows.

General symptoms may include:

    Hearing loss.

  • Tinnitus or ringing of the ear.

  • Stiff neck.

  • Secondary hydroencephalus (accumulation of fluid in the brain).

  • Uncoordinated movement or ataxia in one or both arms.

Specific symptoms may include:

1. Symptoms related to cranial nerve V schwannoma:

  • Paralysis of facial muscle, especially in the same side of the hearing loss.

  • Loss of corneal reflex or the reflex to close the eyelids when the cornea is touched.

2. Symptoms related to cranial nerve VI schwannoma: Double vision.

3. Symptoms related to cranial nerve VII schwannoma: Bell's palsy or sudden onset paralysis of facial muscle, characterized by muscle weakness and distorted facial expression.

4. Symptoms related to cranial nerve X schwannoma: Weakness of the palate, tongue and nerve muscle on the same side as the cancer.


In addition to undergoing a complete physical exam and medical history, your may need one or more of the following tests to diagnose schwannoma:

    X-ray - a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film. Neurofibromas are not seen well on x-rays, but they should be obtained to ensure that the adjacent bone is not involved.

  • Ultrasound - an imaging technology that uses high frequency sound waves to view internal organs and structures and produce diagnostic pictures of the human body. Ultrasound is sometimes useful to detect soft tissue masses.

  • Magnetic Resonance Imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.

  • Biopsy of the tumor - A simple surgical procedure during which a tissue sample from the tumor is taken and then viewed under a microscope.


A neurosurgeon determines the treatment for schwannomas on a case-by-case basis. If the schwannoma is small and asymptomatic, doctors may recommend regular scanning and periodic check-ups to keep an eye on it. Surgery to remove the schwannoma is necessary if the symptoms of the tumor are interfering with quality of life, if the tumor is growing rapidly or if there are signs of malignancy.

The surgery is performed under general anesthesia. Using a microscope and intraoperative electrophysiological monitoring, the nerve is opened and tumor is carefully removed from the nearby functional nerve fascicles. The tumor usually arises from one small nerve fascicle that has been made non-functional by the tumor-this fascicle is removed with the tumor. The remaining nerve fascicles are preserved, thereby maintaining the nerve's function. Surgery is efficacious in resolving pain, weakness, and numbness in the majority (80-90%) of patients.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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