Pain can occur in all forms of neurofibromatosis, in particular, severe and untreatable pain is a hallmark of schwannomatosis, the rarest form of NF affecting an estimated one in every 40,000 individuals. Pain is the most abstract of medical conditions. How can you describe it? And if you cannot describe it, how can a doctor prescribe treatment? With this in mind, it is not surprising that 80% of pain sufferers never receive effective therapy. The February 24 issue of Time takes on the pain issue in an article that highlights potential new effective pain interventions. Brain imaging studies suggest that chronic pain can lead to permanent structural changes in the nervous system, and the common use of opioids to treat pain taps into the brain’s ‘addictive’ circuits which is why these drugs can become difficult to stop taking. One approach being pursued is biofeedback, which is essentially ‘training’ the brain to think of more pleasant things when suffering pain, this has shown some positive results. Magnet therapy has also been used to treat pain, using technology drawn from treatment of bipolar disorder.
One interesting aspect of pain in schwannomatosis is that it does not necessarily occur in the same site as the tumors are present. This ‘displaced’ pain is also the case in phantom limb syndrome where pain is felt even when the appendage is gone. In phantom limb pain this trait has been attributed to excessively high level of signalling of a growth factor called brain derived neurotrophic factor (BDNF). Ongoing Children’s Tumor Foundation-funded research in the lab of Dr. Larry Sherman at Oregon Health Sciences University is testing the theory that BDNF signalling is also hyperactive in mice that have schwannomatosis related pain. With funding from CTF’s Schwannomatosis Awards and Drug Discovery Initiative programs, Dr. Sherman has developed the first ever genetic mouse model of schwannomatosis pain, and is testing drugs from Pfizer and AstraZeneca that target BDNF signaling to see if this will block the pain in the mice. Results are expected later this year.
