What is it?
Peripheral neuropathy often causes numbness and pain in your hands and feet. People typically describe the pain of peripheral neuropathy as tingling or burning, while they may compare the loss of sensation to the feeling of wearing a thin stocking or glove.
Peripheral neuropathy is caused by nerve damage. It can result from such problems as traumatic injuries, infections, metabolic problems and exposure to toxins. One of the most common causes is diabetes.
In many cases, peripheral neuropathy symptoms improve with time — especially if it's caused by an underlying condition that can be treated. A number of medications are often used to reduce the painful symptoms of peripheral neuropathy.
Your nervous system is divided into two broad categories. Your central nervous system consists of your brain and spinal cord. All the other nerves in your body are part of your peripheral nervous system. Peripheral neuropathy affects those nerves, which include:
- Sensory nerves to receive feelings such as heat, pain or touch
- Motor nerves that control how your muscles move
- Autonomic nerves that control such automatic functions as blood pressure, heart rate, digestion and bladder function
Most commonly, peripheral neuropathy may start in the longest nerves — the ones that reach to your toes. Specific symptoms vary, depending on which types of nerves are affected. Signs and symptoms may include:
Gradual onset of numbness and tingling in your feet or hands, which may spread upward into your legs and arms
- Burning pain
- Sharp, jabbing or electric-like pain
- Extreme sensitivity to touch, even light touch
- Lack of coordination
- Muscle weakness or paralysis if motor nerves are affected
- Bowel or bladder problems if autonomic nerves are affected
It's not always easy to pinpoint the cause of peripheral neuropathy, because a number of factors can cause neuropathies. These factors include:
- Trauma or pressure on the nerve. Traumas, such as motor vehicle accidents, falls or sports injuries, can sever or damage peripheral nerves. Nerve pressure can result from using a cast or crutches, spending a long time in an unnatural position, or repeating a motion many times — such as typing.
- Diabetes. When damage occurs to several nerves, the cause frequently is diabetes. At least half of all people with diabetes develop some type of neuropathy.
- Vitamin deficiencies. B vitamins — B-1, B-6 and B-12 — are particularly important to nerve health. Vitamin E and niacin also are crucial to nerve health.
- Alcoholism. Many alcoholics develop peripheral neuropathy because they have poor dietary habits, leading to vitamin deficiencies.
- Infections. Certain viral or bacterial infections can cause peripheral neuropathy, including Lyme disease, shingles (varicella-zoster), Epstein-Barr, hepatitis C and HIV/AIDS.
- Autoimmune diseases. These include lupus, rheumatoid arthritis and Guillain-Barre syndrome.
- Other diseases. Kidney disease, liver disease and an underactive thyroid (hypothyroidism) also can cause peripheral neuropathy.
- Inherited disorders. Examples include Charcot-Marie-Tooth disease and amyloid polyneuropathy.
- Tumours. Growths can form directly on the nerves themselves, or tumours can exert pressure on surrounding nerves. Both cancerous (malignant) and noncancerous (benign) tumours can contribute to peripheral neuropathy.
- Exposure to poisons. These may include some toxic substances, such as heavy metals, and certain medications — especially those used to treat cancer (chemotherapy).
Peripheral neuropathy risk factors include:
- Diabetes, especially if your sugar levels are poorly controlled
- Alcohol abuse
- Vitamin deficiencies, particularly B vitamins
- Infections, such as Lyme disease, shingles (varicella-zoster), Epstein-Barr, hepatitis C and HIV/AIDS
- Autoimmune diseases, such as rheumatoid arthritis and lupus, in which the immune system attacks your own tissues
- Kidney, liver or thyroid disorders
- Exposure to toxins
- Repetitive physical stress, possibly from occupational activities
- Reduced feeling. Because parts of your body may be numb, you may be less likely to feel temperature changes or an injury.
- Infection. Make sure to check your feet, as well as any other areas lacking usual sensation, regularly so that you can treat minor injuries before they become infected. This is especially important for people with diabetes, who tend to heal more slowly.
Peripheral neuropathy isn't a single disease, but rather a symptom with many potential causes. For that reason it can be difficult to diagnose. To help in the diagnosis, your doctor will likely take a full medical history and perform a physical and neurological exam that may include checking your tendon reflexes, your muscle strength and tone, your ability to feel certain sensations, and your posture and coordination.
Your doctor may also request blood tests to check your:
- Vitamin levels
- Thyroid function
- Blood sugar levels
- Liver function
- Kidney function
This test measures the electrical signals in peripheral nerves, and the transfer of that signal to muscles. As a part of this test, you'll be asked to have a nerve conduction study, which measures how quickly your nerves carry electrical signals. A nerve conduction study can be used to diagnose carpal tunnel syndrome and other peripheral nerve disorders.
Additionally, your doctor may recommend a nerve biopsy, a procedure in which a small portion of a nerve is removed and examined for abnormalities. But even a nerve biopsy may not always reveal what's damaging your nerves.
Your doctor may also request a CT scan or MRI to look for herniated disks, tumours or other abnormalities.