What is schwannomatosis?

Schwannomatosis is a recently identified, rare form of neurofibromatosis, also known as neurofibromatosis type 3. The disease leads to the development of benign nerve sheath tumors, called schwannomas, which can form all along spinal and peripheral nerves. These schwannomas can cause chronic and often diffuse pain. Schwannomatosis is often not diagnosed until adulthood.

How is schwannomatosis diagnosed?

Those affected usually see a doctor to address chronic pain during adulthood (median age at the onset of symptoms is 30 years, with a median age at diagnosis of 40 years). During the evaluation of the symptoms, the clinical or imaging examination reveals schwannomas, which can compress or displace nerves and cause pain. However, the location of the pain and the position of the schwannomas are not always well correlated. Nor are the pain intensity and frequency always adequately explained by the presence of the tumor either. Although pain is the most common and usually only complaint, schwannomas – depending on their position – can also cause other neurological symptoms such as numbness, tingling or prickling (paresthesia), bladder and rectal function disorders, visual disorders, and headaches.

One special form of schwannomatosis can be clinically apparent due to cranial pressure symptoms with headaches and vomiting on an empty stomach (vomiting at night or early in the morning after waking up), whereby meningiomas are diagnosed as being the cause in the course of the evaluation. Neurological failures occur depending on the location of the tumor. This form is also called meningiomatosis.

Clinical Diagnostic Criteria

  • Evidence of more than 2 schwannomas which are not located in the skin, with at least one of them confirmed by a tissue analysis
    without evidence of bilateral vestibular schwannomas (a benign tumor of the nerve sheath of cranial nerve 8, the nerve responsible for hearing and balance) in imaging of the head

  • The existence of a schwannoma or intracranial meningioma (usually a benign tumor of the cerebral membranes) confirmed by a tissue analysis
    a first-degree relative (biological parents or children) with schwannomatosis

If there are more than 2 schwannomas which are not located in the skin, even if they have not been confirmed by tissue analysis, the diagnosis of schwannomatosis is nevertheless suspected – especially if there is chronic pain.

Segmental schwannomatosis is defined as the occurrence of schwannomas in only one extremity or limited to 2 spinal segments (30% of patients have segmental schwannomatosis).

What is the risk of cancer?

Depending on the location of the genetic changes, schwannomatosis presents itself in 3 clinically distinct forms:

  • SMARCB1 schwannomatosis is associated with the development of many, often painful, yet benign tumors of the nerve sheaths of peripheral or central nerves (located in the head or spinal canal). The risk of malignant progression is probably slightly elevated. In addition, the risk of developing benign tumors of the meninges (meningiomas) is slightly elevated (5%) as well.

  • LZTR1 schwannomatosis can cause unilateral tumors of cranial nerve 8, the auditory vestibular nerve (vestibular schwannoma).

  • Meningiomatosis (SMARCE1 schwannomatosis) leads to a predisposition to isolated benign central or spinal tumors of the meninges (meningiomas) during childhood.

What causes schwannomatosis?

Schwannomatosis is a relatively rare genetic disease (fewer than 1 in 40,000 people are affected) in which the regulation of cell growth in the nervous system is lost due to changes in the genetic material (mutations). This results in a loss of control over cell proliferation, thereby allowing Schwann cells to form an insulating sheath around the nerve fibers, divide excessively, and develop into schwannomas. Schwannomatosis often appears sporadically; there is only a high family incidence in around 20 percent of cases.

Is there a treatment?

No special treatment for schwannomatosis is known to date. A surgical intervention may be indicated in certain situations, which should then be performed by a doctor who is familiar with the disease. For inoperable schwannomas that cause clinical complaints such as pain, good pain therapy is often the only option for treatment.

Please ask the doctor who is treating you whether there are any open clinical studies in which you can take part.

Surveillance Recommendations for the Early Detection of Cancer

Surveillance Recommendations

Once a diagnosis has been made, patients with schwannomatosis should undergo surveillance measures for early detection in line with the following recommendations (AACR 2016).

SMARCB1 Schwannomatosis

  • A baseline MRI (head and spinal column) at the time of the diagnosis, and then every 2-3 years from 10 years of age or more frequently depending on the clinical picture

  • A whole-body MRI if necessary

LZTR1 Schwannomatosis

  • A baseline MRI (head and spinal column) at the time of diagnosis, and then every 2-3 years from 15-19 years of age or more frequently depending on the clinical picture

  • Consider performing a whole-body MRI.

SMARCE1 Schwannomatosis

  • Neurological examination

  • A baseline MRI (head and spinal column) once a year following the diagnosis until the age of 18, and then every 3 years if no symptoms are evident

  • Shorten the interval if there is evidence of a tumor or clinical symptoms.

Self-Care and Support

What should I pay special attention to?

Please contact your attending doctor or a clinic specializing in neurofibromatosis and set up an appointment right away if you develop any new symptoms such as headaches, visual disorders, or other neurological failures.

Support Groups and Additional Information