It’s not unusual for neurologist Eva Feldman, M.D., to see patients who are experiencing pain or strange sensations in their feet. “They say, ‘My feet hurt, and they hurt worse at night when the sheets are on them.’ ”
Another common complaint she hears: “It feels like bugs are biting the bottom of my feet,” says Feldman, a professor of neurology at the University of Michigan.
A simple blood test, she says, often reveals the cause: high blood sugar. The pain and tingling in their feet are early signs of a condition called peripheral neuropathy, which is a common complication of diabetes.
For many people, these foot symptoms are “the first clear, obvious sign that someone has diabetes or prediabetes,” she says. When caught very early, both the foot pain and the elevated blood sugar can sometimes be reversed, she explains, before permanent nerve damage sets in.
That’s one good example, she and other experts say, of why it’s so important not to ignore any pain, tingling, numbness or weakness in your feet or hands or other symptoms that suggest you could have a form of neuropathy — a catch-all term for damage to nerves that branch out from our brains and spinal cords to the rest of our bodies.
Some of these nerves carry the signals that allow us to feel, for example, that our hands are near a hot stove or our shoes are too tight; others tell our muscles to move, or control processes such as digestion and blood pressure.
Neuropathy can have many causes, can affect one nerve or many, and can have different treatments and varying outlooks. It’s important to get a diagnosis so you can get the right care, the experts say.
“Neuropathy can be a chronic condition that can be accompanied by anxiety and depression,” says Norman Latov, M.D., a professor of neurology at Weill Cornell Medical College in New York. “Understanding what you have and knowing what to expect helps you focus on what needs to be done and reduces the worry and anxiety that come from fearing the unknown.”
Symptoms vary, but there are common patterns
Depending on the kind of neuropathy you have, your symptoms could include:
- Tingling or pain in your feet or hands. The pain may be burning, freezing or shooting and is often worse at night.
- Feeling like you are wearing invisible socks or gloves.
- Feeling weak or unsteady in your feet and legs.
- Extreme sensitivity to touch.
- Loss of balance and coordination.
- Muscle cramping or twitching.
- Abnormalities in pulse or blood pressure.
Sometimes, when neuropathy affects a single nerve, symptoms are clearly confined to one area. For example, the most common single-nerve form of neuropathy, Feldman says, is carpal tunnel syndrome. It happens when the median nerve, which runs from the forearm into the hand, gets inflamed or squeezed, causing numbness, pain and weakness in the hand and wrist.
While sometimes attributed to overuse of the wrists and hands, carpal tunnel can be triggered by arthritis, thyroid disease or injury, according to the Foundation for Peripheral Neuropathy.
When neuropathy affects many nerves, symptoms start or are most severe in the feet about 75 percent of the time, according to the National Institute of Neurological Disorders and Stroke. That’s because the feet are the end point for the longest, most vulnerable nerves in the body, Feldman says.
Most often, she says, symptoms start with foot pain, progress to numbness, then move up the foot and leg. When symptoms reach just below the knee, pain and numbness usually start in the hands as well. Some people get numbness without pain.
Experiencing any of these symptoms? For most people, the first stop should be their regular doctor, Feldman says. An initial workup typically includes screening tests for diabetes, thyroid dysfunction, B12 deficiency and blood proteins associated with certain inflammatory conditions.
People with the most common forms of neuropathy often need no other diagnostic tests, she says. However, some “red flags,” such as one-sided symptoms, weakness or symptoms that develop suddenly, call for a workup by a neurologist, says Gordon Smith, M.D., a professor of neurology at Virginia Commonwealth University. That workup might include tests of your nerve and muscle function.
Diabetes is the biggest — but not the only — cause
Causes of neuropathy affecting multiple nerves can include:
- Diabetes. About half of people with diabetes have some form of neuropathy, according to the American Diabetes Association. It is the most common cause of peripheral neuropathy worldwide, Smith says. In type 2 diabetes, nerve damage is likely caused by high blood sugar and “the metabolic company it keeps,” including obesity, high blood pressure and high cholesterol, he says.
- Medications. Drugs used for cancer chemotherapy and other disorders, including HIV, can cause passing or permanent nerve damage.
- Vitamin B12 deficiency. The nutrient, found in meat, poultry, eggs and fish, plays an important role in nerve health. Levels can drop because of a poor diet or poor absorption of B12, due to certain illnesses or medications.
- Autoimmune diseases. In diseases such as Sjögren’s syndrome (best known for its symptoms of dry eyes and dry mouth), lupus and rheumatoid arthritis, the immune system attacks parts of the body, including nerves.
- Infections. Many infectious diseases, including COVID-19, hepatitis C, hepatitis B and Lyme disease, can cause neuropathy. Shingles, caused by the herpes zoster virus, sometimes causes nerve pain that lingers for months or years.
- Alcohol and other toxins. “Alcohol is a nerve toxin, so that if it’s consumed in excess, especially by those with poor nutritional status, it can damage the nerves,” Latov says. Mercury, lead and arsenic are among other nerve toxins.
- Genes. Some rare disorders, including Charcot-Marie-Tooth disease, are inherited forms of neuropathy.
In about one quarter of cases, no underlying cause is found. But many people in that group have the same risk factors — such as obesity, high cholesterol and high blood pressure — commonly found in people with type 2 diabetes, Smith says. So, he says, the underlying mechanisms could be similar.
Can neuropathy be treated?
There are treatments for neuropathy. However, they mostly aim at underlying causes and symptoms. “By and large, once you have an established neuropathy, it’s hard to reverse it,” Smith says, but the damage often can be slowed.
For people with diabetes, treatment includes blood sugar control, along with changes in diet and exercise to improve overall metabolic health, experts say. Anyone with neuropathy in their feet should see a podiatrist and establish a foot care routine to prevent injuries and infection, Feldman adds.
Some patients need pain medication, but “not all [medications] work for all patients,” Latov says. When one regimen doesn’t work, he says, “it’s important not to give up and to keep trying.”
Mental health care and physical therapy also can help, the doctors say.