Neurofibromatosis is classified into 3 different types:
1. Neurofibromatosis Type 1 (which is what I have been diagnosed with and what this blog focuses on)
2. Neurofibromatosis Type 2 (which is what this blog post will focus on)
Neurofibromatosis Type 2 is much more rare than NF-1, as it occurs 1 in 25,000 people instead of 1 in 3,000. The trademark symptom of NF-2 is tumor growth on the 8th cranial nerve (there are 12 cranial nerves), which is responsible for providing the brain with information relating to balance as well as a sense of sound or hearing. This means that individuals with NF-2 are at a much higher risk for deafness and severe balance problems than those with NF-1 or even those in the general population.
Like people with NF-1, individuals who have Neurofibromatosis Type 2 can develop tumors on other nerves in the body. These tumors are called schwannomas because they typically develop from Schwann cells, which serve to insulate and protect nerve cells so that they can conduct information throughout the brain. Neurofibromatosis Type 2 can also cause vision problems, such as cataracts, orbital tumors and abnormalities of the retina. Facial weakness is another common symptom of NF-2, as are headaches and subcutaneous tumors. People with this type of NF can also have symptoms of NF-1 such as cafe-au-lait spots, but they typically have only a few of these.
Unlike NF-1 which tends to manifest in early childhood, symptoms of NF-2 are generally not noticed until the later teen years or early 20's. The diagnostic criteria is also quite different than that of NF-1, the criteria is as follows:
A diagnosis if NF-2 requires that the patient presents with at least 1 of the following:
- Bilateral vestibular schwannomas (tumors of the 8th cranial nerve present on both sides of the brain)
- A first degree relative with NF-2 (parent, sibling or child) AND|
- Unilateral vestibular schwannoma (tumor of the 8th cranial nerve found on only one side of the brain) OR
- Any 2 of the following: meninginoma (a benign tumor that comes from tissues in the brain), schwannoma, glioma (a malignant or benign tumor of the glial tissue of the nervous system), neurofibroma, and subcapsular lenticular opacities (cataracts)
- Multiple meninginomas AND Unilateral vestibular schwannoma OR
- Any 2 of: schwannoma, glioma, neurofibroma, cataracts
I hope you all learned something new today, enjoy your week!