I may have developed peripheral neuropathy, a nerve problem that can occur in chronic illnesses such as Sjogren's Syndrome. Peripheral neuropathy is most often described as causing numbness and tingling sensations in one or both hands and/or one or both feet. For me, it feels a lot scarier than that - burning sensations in my arms, legs, and sometimes my torso and chest. Itching/prickling sensations. Numbness. Occasional stabbing pain. Cramping in my toes and forearms. Cramping in my thighs and calves. Muscle twitching. Poor fine motor skills - fingers that won't do what I want them to. Feeling like I am vibrating or shaking all over... even though I am not. Feeling like my legs won't hold me up, or like I can't move an arm or a knee. Rapid muscle fatigue and pain with exercise. And extreme, life-flattening exhaustion.
Neuropathy occurs when something injures the nerves and causes them to lose function and/or send false messages to your brain. In autoimmune disease, this phenomenon is related to the immune overactivity that is damaging other parts of your body as well. Sjogren's World has a nice page that reprints a lecture/article by Elaine Alexander on Peripheral Neuropathy and Sjogren's. It explains the various flavors of neuropathy and gives some (slightly outdated) information about treatments. MayoClinic.com has a more updated set of information about peripheral neuropathy treatments and drugs.
If you think you might have neuropathy, you need to go to a neurologist for a thorough exam. When I saw my neurologist, he did things like test my strength in arms, leg, shoulders, hips; check my deep tendon reflexes in arms, legs; and use a safety pin tip to test where my skin registered sharp sensations. Then he recommended a slew of tests to check the function of my nerves.
Testing for neuropathy is not a fun experience. I had it done once before, and all of my results came back negative. This was in early 2008. Now that my symptoms have really ramped up and are a daily problem, they want to put me through all of the tests again.
Step 1 is a nerve conduction study and electromyelogram (EMG). WebMD's Electromyelogram and Nerve Conduction Studies web page explains that an EMG tests for neuromuscular issues (damage to muscles, nerves, and junctions between them), while a nerve conduction study focuses specifically on how signals move through the entire chain of nerves in your body. Both involve getting little zaps of electricity sent through your affected area (they will probably test a leg and/or arm for me). It doesn't hurt, but it's not pleasant, either.
Step 2 is a skin punch biopsy. True peripheral neuropathy is sometimes caused by damage to the small-fiber nerve cells, which are grouped farthest away from the spinal cord, near the surface of your skin. EMG and nerve conduction testing can't detect this kind of neuropathy - your test results will be normal. To check for small-fiber neuropathy, a technician will take a small section of skin from an affected part of your body. They use a small-diameter circular "punch" tool (a tiny open-ended cylinder) to remove the skin. For me, they plan to take one "punch" of skin from my upper thigh, lower thigh/upper knee, and ankle on each leg - for a total of six segments. This skin is then prepped into slides and reviewed by a pathologist. The pathologist is trained to identify damage, swelling, and abnormal nerve cells that may be visible on the slides. Johns Hopkins University's web site includes a detailed explanation of the skin punch biopsy procedure, with pictures.
I found my first skin punch biopsy to be unpleasant at best. I had a hard time lying still long enough for the skin samples to be removed. And then, a few hours later, the biopsy sites really started to hurt. And kept hurting for at least 36 hours. Also, my sites didn't heal up as quickly or prettily as the take-home instructions said they would. So plan to have advil handy and be careful about washing and drying your biopsy sites until they are fully healed! Also, if you take blood thinning medications, be sure to stop taking them two weeks before the procedure, so you don't bleed excessively.