Schwannomatosis is the third rarest, form of neurofibromatosis affecting around 1 in 40,000 people. This condition is distinguishable from NF2 in that people affected by this condition do not develop tumours on the hearing nerves (vestibular nerves).
Common signs and symptoms
The features of Schwannomatosis include the formation of benign tumours (schwannomas) on cells, called Schwann cells, which surround the nerves and allow them to conduct information around the body. These tumours typically develop on cranial, spinal and peripheral nerves, but as noted above do not form on the hearing nerves. Also, unlike in NF2, people affected with Schwannomatosis do not go on to develop any other types of tumour.
The diagnostic criteria for this condition are still evolving. This is due to the condition only recently having been characterised, and only a small number of people affected identified. As more research is conducted, and more people with the condition identified a more definitive criteria for diagnosis will form. See Diagnosis for details of the current criteria.
Often those affected by Schwannomatosis suffer from chronic pain, which can be disproportionately larger than the neurological problems they have. This is also often the first symptom of the condition. This pain can occur in any part of the body. As pain is often the only symptom diagnosis can often take a considerable length of time.
What is the cause of Schwannomatosis?
The genetics of Schwannomatosis is more complex than that of NF1 and NF2. While families affected by this condition usually show an autosomal dominant form of inheritance (see Genetics) it sometimes appears as if the condition skips generations and therefore a careful family history needs to be taken down to include anyone in the family who showed symptoms of unexplained pain. Genetic testing is not currently available for Schwannomatosis as the specific genes involved are still being researched, though a candidate gene, and several potentially associated ones have been identified.
A diagnosis of mosaic (or segmental) Schwannomatosis is also possible. This arises where only one area of the body is affected by the condition.
Like with NF1 and NF2 there is currently no cure or medical treatment for the condition. People affected are treated based upon the symptoms they present with.
Further information sheets are available in Factsheets.