8 questions about peripheral neuropathy
All of us have had that sensation of numbness or “pins and needles” in our arms and legs at some point—perhaps after sitting the wrong way or sleeping in a funny position, causing the limbs to “fall asleep” temporarily. Now imagine if that sensation never went away. That’s what millions of people in the U.S. experience every day, due to a condition known as peripheral neuropathy. Here are some basics about the condition and how, while not curable, it can be made easier to live with.
1. What is peripheral neuropathy?
Peripheral neuropathy refers to a condition in which the nerves going from the brain and spinal cord to the legs, feet, arms, or hands are damaged. As a result, nerves no longer conduct impulses properly, either transmitting signals poorly or spontaneously activating. Depending on which nerves are damaged, the person may experience pain or numbness, a burning or tingling sensation, increased sensitivity to touch, muscle weakness, or a number of other symptoms in the extremities connected to the affected nerves.
2. Who’s most at risk?
The most common risk factor is diabetes, especially in those who are over 40 years old, have had diabetes for more than 25 years, and have poorly controlled blood sugar. Prediabetes, in which blood sugar is only modestly elevated, also appears to increase the risk of peripheral neuropathy—one more reason to reduce blood sugar levels before full-blown diabetes develops.
Other people at increased risk for peripheral neuropathy include smokers; those who abuse alcohol; those undergoing chemotherapy; and those who have autoimmune diseases (such as lupus or rheumatoid arthritis), liver or kidney disease, or a vitamin B1 (thiamine), vitamin B12, or iron deficiency. Mechanical damage to nerves, as with carpal tunnel syndrome, can also cause the disorder. Many medications can cause peripheral neuropathy. In about 30 percent of cases, no cause can be identified.
3. How does peripheral neuropathy develop?
It depends somewhat on the type (there are about 100 different types of peripheral neuropathy, which vary in terms of which nerves they affect, the specific symptoms they cause, and how they develop). But in general, experts believe that compounds that cause inflammation, as well as specific growth factors and proteins that affect nerve signaling, may all play a role. Among people with diabetes or prediabetes, increased free radicals and abnormal blood sugar levels are believed to contribute to nerve damage.
4. How is it diagnosed?
If you are at risk for peripheral neuropathy or are experiencing symptoms, your health care provider can screen for the condition in the office with some quick neurological tests that check your ability to detect pain, light touch, and vibration on the skin, as well as evaluate your reflexes and muscle strength. If the results suggest you have peripheral neuropathy, additional tests will probably be done to determine the type; those may include blood tests, electromyography (which involves inserting a fine needle into a muscle to determine its electrical activity), or nerve conduction velocity tests, which use a probe to stimulate a nerve and analyze how its fibers are functioning. Less commonly, a nerve biopsy will be performed.
5. How is peripheral neuropathy treated?
How it is treated and whether it is reversible depend on the cause and the severity of the neuropathy. If caused by a nutritional deficiency, for example, correcting the deficiency should alleviate the neuropathy; if it is a side effect of medication, switching to a different drug should help. But with some causes the damage is likely to be permanent. For instance, if the nerve damage is related to diabetes or another underlying disease, treating or at least controlling the disease may only prevent the worsening of neuropathy. In that case, there are treatments that target the symptoms, such as pain and tingling. Over-the-counter anti-inflammatory pain relievers can help mild cases. A variety of prescription medications may also be used, including several antidepressant and anti-seizure drugs (usually prescribed off-label). If your pain is limited to one area, your health care provider may recommend a topical treatment, such as a patch containing capsaicin (found in hot peppers) or lidocaine (an anesthetic).
A research review on medical marijuana as a treatment for chronic pain, funded by the VA Administration and published in the Annals of Internal Medicine in August 2017, included 13 clinical trials focusing on peripheral neuropathy. It concluded that marijuana may help some people with the condition. But more studies are needed on its long-term safety and efficacy.
Transcutaneous electrical nerve stimulation, or TENS, may also be a viable option. It can be administered at your doctor’s office or, if your doctor recommends it, on your own at home. TENS involves applying electrodes to the skin on or near the painful spot while an attached device emits a gentle electrical stimulus. A review paper published in Pain Management found evidence that 4 to 6 weeks of TENS treatments may significantly improve various types of pain. The treatment may also help reduce numbness and boost quality of life in people withdiabetic peripheral neuropathy, the review found. Often, a combination of treatment approaches will provide the best relief.
6. Are there other non-drug strategies that can help?
Yes, and they’re worth trying before or in addition to conventional therapies. Seeing a skilled physical therapist can improve your physical functioning, and a type of psychological therapy called cognitive behavioral therapy can help counter negative thinking or changes in behavior that can exacerbate anxiety and pain. Some evidence suggests that diet and exercise may both prevent and reverse nerve damage from peripheral neuropathy in people with diabetes or prediabetes, as well as reduce symptoms. A review paper in the journal Frontiers in Cellular Neuroscience, for instance, concluded that exercise can be highly beneficial for preventing peripheral neuropathy and alleviating its symptoms by preserving and promoting nerve function, reducing pain, and improving sensation.
In addition, if you have peripheral neuropathy, it’s important to examine your legs and feet regularly for things like cuts, bruises, or blisters. If sensation in these areas is reduced, you may not notice such injuries, which need to be treated promptly to reduce the risk of more serious problems like infection.
7. What about alternative or complementary therapies?
Relaxation techniques such as deep, controlled breathing and muscle relaxation are worth a try for reducing pain and discomfort. Acupuncture is another option—though, as with relaxation techniques, there’s limited evidence to support its effectiveness, and many of the studies have methodological problems.
A type of biofeedback called neurofeedback may help treat people with chemotherapy-induced peripheral neuropathy. The treatment typically involves placing electrodes on the affected person’s scalp that pick up the brain’s activity (including pain), which is displayed on a video screen. Participants are taught how to reduce the pain-associated brain waves through playing a video game that responds to their brain activity. In a small study of patients with cancer who were experiencing peripheral neuropathy, conducted at the University of Texas MD Anderson Cancer Center, those who were trained to alter their pain-related brain waves through electroencephalopathy (EEG) feedback experienced a significant improvement in pain, numbness, and quality of life compared with those who were not trained.
8. Can peripheral neuropathy be prevented?
For people with diabetes, preventive strategies include keeping blood sugar well controlled, exercising regularly, quitting smoking, not drinking excessively, and maintaining a healthy body weight and blood pressure. To prevent chemotherapy-induced peripheral neuropathy, your health care provider may use smaller doses of chemotherapy administered more frequently, or give the same dose over a longer time period.