Neuropathy (Peripheral Neuropathy)
What is neuropathy?
Neuropathy is damage or dysfunction of one or more nerves that typically results in numbness, tingling, muscle weakness and pain in the affected area. Neuropathies frequently start in your hands and feet, but other parts of your body can be affected too.
Neuropathy, often called peripheral neuropathy, indicates a problem within the peripheral nervous system. Your peripheral nervous system is the network of nerves outside your brain and spinal cord. Your brain and spinal cord make up your central nervous system. Think of the two systems working together this way: Your central nervous system is the central station. It is the control center, the hub from which all trains come and go. Your peripheral nervous system are the tracks that connect to the central station. The tracks (the network of nerves) allow the trains (information signals) to travel to and from the central station (your brain and spinal cord).
Neuropathy results when nerve cells, called neurons, are damaged or destroyed. This disrupts the way the neurons communicate with each other and with the brain. Neuropathy can affect one nerve (mononeuropathy) or nerve type, a combination of nerves in a limited area (multifocal neuropathy) or many peripheral nerves throughout the body (polyneuropathy).
What types of peripheral nerves are there and what do they do?
The peripheral nervous system is made up of three types of nerves, each with an important role in keeping your body healthy and functioning properly.
- Sensory nerves carry messages from your five senses (sight, hearing, smell, taste, touch) through your spinal cord to your brain. For example, a sensory nerve would communicate to your brain information about objects you hold in your hand, like pain, temperature, and texture.
- Motor nerves travel in the opposite direction of sensory nerves. They carry messages from your brain to your muscles. They tell your muscles how and when to contract to produce movement. For example, to move your hand away from something hot.
- Autonomic nerves are responsible for body functions that occur outside of your direct control, such as breathing, digestion, heart rate, blood pressure, sweating, bladder control and sexual arousal. The autonomic nerves are constantly monitoring and responding to external stresses and bodily needs. For instance, when you exercise, your body temperatures increases. The autonomic nervous system triggers sweating to prevent your body's temperature from rising too high.
The type of symptoms you feel depend on the type of nerve that is damaged.
What does neuropathy feel like?
If you have neuropathy, the most commonly described feelings are sensations of numbness, tingling (“pins and needles”), and weakness in the area of the body affected. Other sensations include sharp, lightening-like pain; or a burning, throbbing or stabbing pain.
How common is neuropathy? Who gets neuropathy?
Neuropathy is very common. It is estimated that about 25% to 30% of Americans will be affected by neuropathy. The condition affects people of all ages; however, older people are at increased risk. About 8% of adults over 65 years of age report some degree of neuropathy. Other than age, in the United States some of the more common risk factors for neuropathy include diabetes, metabolic syndrome (high blood pressure, high cholesterol, obesity, diabetes), and heavy alcohol use. People in certain professions, such as those that require repetitive motions, have a greater chance of developing mononeuropathies from trauma or compression of nerves.
Among other commonly cited statistics, neuropathy is present in:
- 60% to 70% of people with diabetes.
- 30% to 40% of people who receive chemotherapy to treat cancer.
- 30% of people who have human immunodeficiency virus (HIV).
How quickly does neuropathy develop?
Some peripheral neuropathies develop slowly – over months to years – while others develop more rapidly and continue to get worse. There are over 100 types of neuropathies and each type can develop differently. The way your condition progresses and how quickly your symptoms start can vary greatly depending on the type of nerve or nerves damaged, and the underlying cause of the condition.
There are many causes of neuropathy. Diabetes is the number one cause in the United States. Other common causes include trauma, chemotherapy, alcoholism and autoimmune diseases.
What causes neuropathy?
Neuropathy is not caused by a single disease. Many conditions and events that impact health can cause neuropathy, including:
- Diabetes: This is a leading cause of neuropathy in the United States. Some 60% to 70% of people with diabetes experience neuropathy. Diabetes is the most common cause of small fiber neuropathy, a condition that causes painful burning sensations in the hands and feet.
- Trauma: Injuries from falls, car accidents, fractures or sports activities can result in neuropathy. Compression of the nerves due to repetitive stress or narrowing of the space through which nerves run are other causes.
- Autoimmune disorders and infections: Guillain-Barré syndrome, lupus, rheumatoid arthritis, Sjogren’s syndrome and chronic inflammatory demyelinating polyneuropathy are autoimmune disorders that can cause neuropathy. Infections including chickenpox, shingles, human immunodeficiency virus (HIV), herpes, syphilis, Lyme disease, leprosy, West Nile virus, Epstein-Barr virus and hepatitis C can also cause neuropathy.
- Other health conditions: Neuropathy can result from kidney disorders, liver disorders, hypothyroidism, tumors (cancer-causing or benign) that press on nerves or invade their space, myeloma, lymphoma and monoclonal gammopathy.
- Medications and poisons: Some antibiotics, some anti-seizures medications and some HIV medications among others can cause neuropathy. Some treatments, including cancer chemotherapy and radiation, can damage peripheral nerves. Exposure to toxic substances such as heavy metals (including lead and mercury) and industrial chemicals, especially solvents, can also affect nerve function.
- Vascular disorders: Neuropathy can occur when blood flow to the arms and legs is decreased or slowed by inflammation, blood clots, or other blood vessel disorders. Decreased blood flow deprives the nerve cells of oxygen, causing nerve damage or nerve cell death. Vascular problems can be caused by vasculitis, smoking and diabetes.
- Abnormal vitamin levels and alcoholism: Proper levels of vitamins E, B1, B6, B12, and niacin are important for healthy nerve function. Chronic alcoholism, which typically results in lack of a well-rounded diet, robs the body of thiamine and other essential nutrients needed for nerve function. Alcohol may also be directly toxic to peripheral nerves.
- Inherited disorders: Charcot-Marie-Tooth (CMT) disease is the most common hereditary neuropathy. CMT causes weakness in the foot and lower leg muscles and can also affect the muscles in the hands. Familial amyloidosis, Fabry disease and metachromatic leukodystrophy are other examples of inherited disorders that can cause neuropathy.
- No known cause: Some cases of neuropathy have no known cause.
What are the symptoms of neuropathy?
Symptoms of neuropathy vary depending on the type and location of the nerves involved. Symptoms can appear suddenly, which is called acute neuropathy, or develop slowly over time, called chronic neuropathy.
Common signs and symptoms of neuropathy include:
- Tingling (“pins and needles”) or numbness, especially in the hands and feet. Sensations can spread to the arms and legs.
- Sharp, burning, throbbing, stabbing or electric-like pain.
- Changes in sensation. Severe pain, especially at night. Inability to feel pain, pressure, temperature or touch. Extreme sensitivity to touch.
- Falling, loss of coordination.
- Not being able to feel things in your feet and hands – feeling like you’re wearing socks or gloves when you’re not.
- Muscle weakness, difficulty walking or moving your arms or legs.
- Muscle twitching, cramps and/or spasms.
- Inability to move a part of the body (paralysis). Loss of muscle control, loss of muscle tone or dropping things out of your hand.
- Low blood pressure or abnormal heart rate, which causes dizziness when standing up, fainting or lightheadedness.
- Sweating too much or not enough in relation to the temperature or degree or exertion.
- Problems with bladder (urination), digestion (including bloating, nausea/vomiting) and bowels (including diarrhea, constipation).
- Sexual function problems.
- Weight loss (unintentional).