What Is Neuropathy?

Peripheral neuropathy, a result of damage to the nerves located outside the brain and spinal cord (peripheral nerves), often causes weakness, numbness and pain, usually in the hands and feet. It can also affect other areas and body functions including digestion, urination and circulation.

Your peripheral nervous system sends information from your brain and spinal cord (central nervous system) to the rest of your body. The peripheral nerves also send sensory information to the central nervous system.

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

People with peripheral neuropathy generally describe the pain as stabbing, burning or tingling. In many cases, symptoms improve, especially if caused by a treatable condition. Medications can reduce the pain of peripheral neuropathy.

Symptoms of Neuropathy

Every nerve in your peripheral system has a specific function, so symptoms depend on the type of nerves affected. Nerves are classified into:

• Sensory nerves that receive sensation, 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, perspiration, heart rate, digestion and bladder function

Signs and symptoms of peripheral neuropathy might include:

• Gradual onset of numbness, prickling or tingling in your feet or hands, which can spread upward into your 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
• Paralysis if motor nerves are affected

If autonomic nerves are affected, signs and symptoms might include:

• Heat intolerance
• Excessive sweating or not being able to sweat
• Bowel, bladder or digestive problems
• Drops in blood pressure, causing dizziness or lightheadedness

Peripheral neuropathy can affect one nerve (mononeuropathy), two or more nerves in different areas (multiple mononeuropathy), or many nerves (polyneuropathy). Carpal tunnel syndrome is an example of mononeuropathy. Most people with peripheral neuropathy have polyneuropathy.

When to see a doctor

Seek medical care right away if you notice unusual tingling, weakness or pain in your hands or feet. Early diagnosis and treatment offer the best chance for controlling your symptoms and preventing further damage to your peripheral nerves.

Causes

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

• Autoimmune diseases. These include Sjogren's syndrome, lupus, rheumatoid arthritis, Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy and vasculitis.
• Diabetes. This is the most common cause. Among people with diabetes, more than halfwill develop some type of neuropathy.
• Infections. These include certain viral or bacterial infections, including Lyme disease, shingles, Epstein-Barr virus, hepatitis B and C, leprosy, diphtheria, and HIV.
• Inherited disorders. Disorders such as Charcot-Marie-Tooth disease are hereditary types of neuropathy.
• Bone marrow disorders. These include an abnormal protein in the blood (monoclonal gammopathies), a form of bone cancer (myeloma), lymphoma and the rare disease amyloidosis.
• Other diseases. These include kidney disease, liver disease, connective tissue disorders and an underactive thyroid (hypothyroidism).

Other causes of neuropathies include:

• Alcoholism. Poor dietary choices made by people with alcoholism can lead to vitamin deficiencies.
• Exposure to poisons. Toxic substances include industrial chemicals and heavy metals such as lead and mercury.
• Medications. Certain medications, especially those used to treat cancer (chemotherapy), can cause peripheral neuropathy.
• Injury or pressure on the nerve. 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 or using crutches or repeating a motion such as typing many times.
• Vitamin deficiencies. B vitamins — including B-1, B-6 and B-12 — vitamin E and niacin are crucial to nerve health.