What is neuropathy?
Neuropathy – also called peripheral neuropathy – refers to any condition that affects the normal activity of the nerves of the peripheral nervous system. The peripheral nervous system is the network of nerves that connects the central nervous system – the brain and spinal cord – to the rest of the body.
The peripheral nervous system is made up of 3 types of nerves, each with an important role to play in keeping your body healthy and functioning properly.
- Sensory nerves carry messages from your senses through your spinal cord to your brain. For example, they tell your brain you are touching something hot.
- Motor nerves travel in the opposite direction. They carry messages from the brain to your muscles. They tell your muscles to move you away from the hot surface.
- Autonomic nerves are responsible for controlling body functions that occur outside our control, such as breathing, digestion, heart rate, and blood pressure.
Neuropathy results when nerve cells, or neurons, are damaged or destroyed. This distorts the way the neurons communicate with each other and with the brain. Neuropathy can affect 1 nerve or nerve type, or a combination of nerves.
How common is neuropathy?
Neuropathy is very common. It is estimated that about 25% to 30% of Americans will be affected by neuropathy. Neuropathy occurs in 60% to 70% of people with diabetes.
Who gets neuropathy?
Neuropathy affects people of all ages; however, older people are at increased risk. It is more common in men and in Caucasians. People in certain professions, such as those that require repetitive motions, have a greater chance of developing compression-related neuropathy.
What causes neuropathy?
There are many causes of neuropathy. The cause can be hereditary (runs in families) or acquired (develops after birth).
The most common hereditary neuropathy is Charcot-Marie-Tooth (CMT) disease, which affects both motor and sensory nerves. CMT affects about one in 2,500 people in the United States. CMT causes weakness in the foot and lower leg muscles. Deformities of the feet are also common, making it difficult to walk and often resulting in falls. In its later stages, CMT can also affect the muscles in the hands. There is no cure for hereditary neuropathy.
Acquired neuropathy is much more common. There are many causes of acquired neuropathy, including:
- Trauma: This includes sudden injury from an event such as a fall, car accident or sports activity. Trauma to the peripheral nerves can also occur from compression of the nerves due to repetitive stress or narrowing of the nerve space.
- Infections and autoimmune disorders: Among the germs that can damage nerve fibers are human immunodeficiency virus (HIV), the herpes virus, and the bacteria that cause Lyme disease and syphilis. Some autoimmune disorders can also affect nerve tissue. Examples include Guillain-Barré syndrome, systemic lupus erythematosus, and rheumatoid arthritis.
- Systemic diseases: Systemic diseases are those that affect the entire body. These include diabetes – the leading cause of peripheral neuropathy – kidney disorders, certain cancers, and hormonal imbalances.
- Medications and poisons: Some medicines, including the strong medicines used to treat cancer (chemotherapy), 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 hindered 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.
- Vitamin imbalances: Proper levels of vitamins E, B1, B6, B9, B12, and niacin are important for healthy nerve function.
- Alcoholism: Excessive use of alcohol can rob the body of thiamine and other essential nutrients, leading to neuropathy in the arms and legs.
When the cause of the neuropathy cannot be determined, it is called idiopathic neuropathy. About 30 to 40% of neuropathy cases are idiopathic. Another 30% are the result of diabetes.
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 symptoms of sensory neuropathy include:
- Numbness, especially in the hands and feet.
- Changes in sensation — Some people feel severe pain, especially at night, and some are unable to feel pain, pressure, temperature, or touch.
- Loss of coordination.
- Loss of reflexes.
- Burning sensation.
- Feeling that you are wearing socks or gloves when you are not.
Common symptoms of motor neuropathy include:
- Muscle weakness.
- Difficulty walking or moving your arms or legs.
- Muscle twitching.
- Loss of muscle control.
- Loss of muscle tone.
- Loss of dexterity.
- Inability to move a part of the body.
Common symptoms of autonomic neuropathy include:
- Abnormal blood pressure or heart rate.
- Decreased sweating.
- Problems with urination.
- Sexual dysfunction.
- Weight loss (unintentional).
- Dizziness when standing up or fainting.
- Nausea or vomiting.
- Problems with digestion.