Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at October 2, 2016

Schwannomatosis is one of three types of neurofibromatosis. While neurofibromatosis 1 can manifest as skin tumors and bone deformities, patients who suffer neurofibromatosis 2 develop slow growing tumors in the ear on the nerve that carries information to the brain. Schwannomatosis is the rarest version of the condition and manifests as tumors on the spinal nerves and cranial nerves, and can appear on other nerves throughout the body. Patients who suffer from schwannomatosis suffer chronic pain, a loss of muscle tone, weakness, and numbness.


Definition & Facts

Schwannomatosis is found to affect 1 in 40,000 individuals. The condition refers to the development of schwannomas, or tumors on cranial, spinal and peripheral nervess.

These tumors are over-growths of Schwann cells, or cells of the nerve sheath. Schwannomas cause damage by chafing against and shredding the nerve fibers. These tumors can also press against bone and cause pain

Schwannomatosis tumors are rarely malignant. With careful monitoring of the tumor, pain medication and surgical treatment when possible, schwannomatosis patients and their physicians can often find a workable method of pain management.

Symptoms & Complaints

While neurofibromatosis 1 displays physical manifestations including tumors and neurofibromatosis 2 results in measurable hearing loss, schwannomatosis manifests primarily as pain. Additionally, neurofibromatosis 1 and 2 manifest in childhood and adolescence. 

Schwannomatosis develops in early adulthood. Patients may suffer from chronic pain for years before the condition is diagnosed. Patients can also suffer segmental schwannomatosis, which limits pain to single regions of the body or spine.

Depending on the location and size of the schwannomas, misdiagnosis can add to the suffering. Anyone with a family history of neurofibromatosis who develops chronic pain in early adulthood would benefit from testing for schwannomatosis.


Schwannomatosis is a genetic disorder but does not show a consistent inheritance pattern. The condition skips generations. While there is genetic testing available for neurofibromatosis, no gene has yet been isolated and shown to carry schwannomatosis. Careful review of direct family history including the health conditions of grandparents need to be studied to trace the risk of schwannomatosis.

Currently, schwannomatosis is thought to be associated with chromosome 22. This chromosome normally functions as a tumor suppressor. Genetic mutations which result in neurofibromatosis 1 and 2, schwannomatosis, and rare malignancies affecting the brain and kidneys, often developing in infancy.

Diagnosis & Tests

Schwannomatosis generally develops in adulthood. To confirm schwannomatosis, the patient must display the following:

  • Be more than 30 years old
  • Display schwannoma tumors along the nerve sheath, not under the skin
  • Not have the neurofibromatosis 2 gene, or
  • Display one pathologically confirmed schwannoma tumor and have a close relative who has the symptoms listed above. In this instance, a close or first degree relative refers to the patient's grandparent, parent or sibling.

Patients who manifest symptoms of schwannomatosis need to be tested for neurofibromatosis because of the risk of malignancy common to that condition. Additionally, if the patient suffers from neurofibromatosis 2, surgical and drug treatments for hearing problems and difficulties with balance need to be undertaken in a timely fashion.

As previously stated, schwannomatosis tumors rarely develop malignancies. However, locating the tumor and monitoring any damage to the nerve is critical in helping the patient manage their pain and maintain muscle strength.

Treatment & Therapy

Proper diagnosis through medical imaging is critical for effective treatment of schwannomatosis. Pain management can best be implemented with careful visual observation and imaging of the tumor site. Medication for pain management is recommended for tumors that cannot be corrected surgically.

Surgical treatment is possible and recommended for peripheral nerve tumor growths. Microsurgery is a growing field of opportunity, including image-guided surgery to offer the safest and least invasive tumor removal.

Another treatment option for schwannoma tumors is radiosurgery, a form of radiotherapy. During this technique, concentrated high doses of radiation to the tumor to kill the growth without impacting nearby tissue. For large tumors or those located near nerves that impact critical systems including sight, hearing and breathing, radiosurgery can be done in stages to allow the nerves of these critical systems time to heal before the next round of treatment.

Prevention & Prophylaxis

Schwannomatosis is a genetic condition that is difficult to trace because it skips generations. Also, as it has no known genetic test at this time, it can't yet be determined in utero or by any form of genetic testing. Because the condition doesn't manifest until adulthood for most patients, schwannomatosis cannot be prevented. 

The symptoms of schwannomatosis can develop after hormonal changes including puberty and pregnancy. Young adult females who develop chronic pain and have a family history of neurofibromatosis should be tested as their condition may impact if and when they choose to start a family. Current studies indicate no additional risk of oral contraceptives impacting tumor growth for those who suffer from neurofibromatosis 1. However, schwannomatosis patients struggling with tumors of any size on the spine may be severely impacted by the additional weight of a pregnancy and limited access to pain medications during pregnancy. 

However, those with a family history of neurofibromatosis who develop chronic pain in early adulthood should be tested for schwannomatosis. The damage caused by schwannoma tumors can be monitored and medicated to bring relief, and some tumors can be surgically treated. Additionally, schwannoma tumors generally are very slow growing; however, detailed and consistent imaging can give schwannomatosis patients and their medical professionals detailed information about any sudden changes in tumor size and growth pattern.

Knowledge of the conditions gathered under the umbrella of neurofibromatosis are growing. Those with a family history of the condition need to be monitored and tested for various versions of the illness. While schwannomatosis generally does not manifest in malignant tumor growth, neurofibromatosis 1 and 2 tumors can develop malignancies, so careful imaging and monitoring must be undertaken to determine there is no change in the growth rate of tumors connected with these conditions.