Peripheral neuropathy

Peripheral neuropathy happens when the peripheral nerves, which are located outside of the brain and spinal cord, are damaged. This condition often causes weakness, numbness and pain, usually in the hands and feet. It also can affect other areas and body functions, including digestion and urination.

The peripheral nervous system sends information from the brain and spinal cord, also called the central nervous system, to the rest of the body through motor nerves. The peripheral nerves also send sensory information from the skin, tendons, joints and organs to the central nervous system through sensory nerves.

Peripheral neuropathy can result from traumatic injuries, infections, metabolic conditions, autoimmune diseases, inherited causes and exposure to toxins. One of the most common causes of neuropathy is diabetes.

People with peripheral neuropathy usually describe the pain as stabbing, burning or tingling. Sometimes symptoms get better, especially if caused by a condition that can be treated. Medicines can reduce the pain of peripheral neuropathy.

Every nerve in the peripheral system has a specific job. Symptoms of peripheral neuropathy depend on the types of nerves affected. Nerves are divided into:

• Sensory nerves that receive sensation information, such as temperature, pain, vibration or touch, from the skin.
• Motor nerves that control muscle movement.
• Autonomic nerves that control functions such as blood pressure, sweating, heart rate, digestion and bladder function.

Symptoms of peripheral neuropathy might include:

• Gradual onset of numbness, prickling or tingling in the feet or hands. These sensations can spread upward into the legs and arms.
• Sharp, jabbing, throbbing or burning pain.
• Extreme sensitivity to touch.
• Pain during activities that shouldn't cause pain, such as pain in your feet when putting weight on them or when they're under a blanket.
• Lack of coordination and falling.
• Muscle weakness.
• Feeling as if you're wearing gloves or socks when you're not.
• Loss of the ability to move if motor nerves are affected.

If autonomic nerves are affected, symptoms might include:

• Heat intolerance.
• A lot of sweating or not being able to sweat.
• Trouble with bowel, bladder or digestive system.
• Drops in blood pressure, causing dizziness or lightheadedness.

If peripheral neuropathy affects one nerve, it's called mononeuropathy. If it affects two or more nerves in different areas, it's called multiple mononeuropathies. If it affects many nerves all over the body, it's called polyneuropathy. Carpal tunnel syndrome is an example of mononeuropathy. Most people with peripheral neuropathy have polyneuropathy.

Peripheral neuropathy is nerve damage caused by several different conditions. Health conditions that can cause peripheral neuropathy include:

• Autoimmune diseases. These include Sjogren syndrome, lupus, rheumatoid arthritis, Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy and vasculitis. Also, some cancers related to the body's immune system can cause polyneuropathy. These are a form of the autoimmune disorder called paraneoplastic syndrome.
• Diabetes and metabolic syndrome. These are the most common causes. Among people with diabetes, more than half develop some type of neuropathy.
• Infections. These include certain viral or bacterial infections, including Lyme disease, shingles, hepatitis B and C, leprosy, diphtheria, and HIV.
• Inherited conditions. Conditions such as Charcot-Marie-Tooth disease are hereditary types of neuropathies that run in families.
• Tumors. Growths that are cancerous, also called malignant—or noncancerous, also called benign—can happen on or press on nerves.
• Bone marrow conditions. These include conditions such as monoclonal gammopathies, caused by a protein in the blood that isn't usually there. Other conditions are lymphoma, the rare disease amyloidosis and a rare form of myeloma that affects the bones.
• Other health concerns. These include metabolic conditions such as kidney disease or liver disease and an underactive thyroid, also known as hypothyroidism.

Other causes of peripheral neuropathy include:

• Alcohol use disorder. Less healthy dietary choices made by people with alcohol use disorder, also known as alcoholism, and poor absorption of vitamins caused by alcohol use can lead to low amounts of essential vitamins in the body.
• Exposure to poisons. Toxic substances include industrial chemicals and heavy metals such as lead and mercury.
• Medicines. Certain medicines, especially chemotherapy used to treat cancer, can cause peripheral neuropathy.
• Injuries or pressure on nerves. Injuries, such as from motor vehicle accidents, falls or sports injuries, can sever or damage peripheral nerves. Nerve pressure can result from having a cast, using crutches or repeating a motion, such as typing many times.
• Low vitamin levels. B vitamins, including B-1, B-6 and B-12, copper and vitamin E are crucial to nerve health.

Sometimes, no cause can be identified. This is called idiopathic peripheral neuropathy.

Peripheral neuropathy risk factors include:

• Diabetes, especially if sugar levels are not well managed.
• Obesity.
• Metabolic syndrome.
• Alcohol misuse.
• Low levels of vitamins in the body, especially vitamin B-12.
• Infections, such as Lyme disease, shingles, hepatitis B and C, and HIV.
• Autoimmune diseases, such as rheumatoid arthritis and lupus, in which the immune system attacks the body's tissues.
• Kidney, liver or thyroid disorders.
• Exposure to toxins.
• Repetitive motion, such as those done in certain jobs.
• Family history of neuropathy.

Complications of peripheral neuropathy can include:

• Burns, skin injuries and wounds on the feet. You might not feel temperature changes or pain on parts of your body that are numb.
• Infection. Your feet and other areas that lack sensation can become injured without your knowing. Check these areas regularly, wear close-toed, well-fitting shoes and treat minor injuries before they become infected, especially if you have diabetes.
• Falls. Weakness and loss of sensation may be associated with a lack of balance and falling. Installing handrails in the bathroom, using canes or walkers when needed, and ensuring you walk only in well-lit rooms can decrease fall risk.