The problem for SFPN sufferers – and ME/CFS and FM – has been that the diseases are invisible. There’s no way to tell from the outside that the small nerve fibers in your skin or elsewhere have been damaged or destroyed.
If you have SFPN you’ll probably complain of a range of unconnected, seemingly vague symptoms. Small nerve fiber problems can be driving you nuts – causing you to experience weird sensations, numbness, pain, problems standing, racing heart, gut issues – while you will look fine. When your strength and reflex and other tests turn out normal your doctor will probably think you are nuts and act accordingly.
The reason these small nerve fibers could be causing so much havoc is that they do so much. Dr. Oaklander lead off her 2015 Immunotherapy paper by calling attention to just how strange the small, unmyelinated C and thinly myelinated D nerve fibers she’s studying are. These primitive nerve fibers engage in an astonishing array of activities. Not only do they transmit pain and sensory signals, they also release substances that trigger edema, vasodilation, modulate immune responses (including mast cell activity), and affect autonomic nervous system functioning. In turn, they are also affected by the immune system.
When small nerve fibers are damaged, you have small fiber polyneuropathy (SFPN). In contrast to the small nerve neuropathy found in the skin,
SFPN affects peripheral nerves across the body causing potentially a staggering array of symptoms from pain to tachycardia, orthostatic intolerance (problems standing), headache, exercise intolerance (due to circulatory insufficiency), gut issues, cognitive problems and more.
That large array of potential symptoms suggests SFPN could be causing every ME/CFS and FM symptom in the book.
