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Peripheral Neuropathy: Signs, Causes & Treatment

Peripheral Neuropathy: Signs, Causes & Treatment

What is Peripheral Neuropathy?

Peripheral neuropathy is a term to describe damage to the peripheral nervous system, which relays messages from the brain to the rest of the body. Damage to this system can cause various health complications. Peripheral neuropathy affects approximately 20 million people in the United States alone. It may affect different areas of the peripheral nervous system—the motor, sensory and autonomic nerves. Peripheral neuropathy interferes with the brain’s ability to properly communicate messages throughout the body. This condition may result from physical injuries, autoimmune diseases, infections, alcoholism and exposure to toxins (x).

The Peripheral Nervous System

There are two structural components of the nervous system: the central nervous system and peripheral nervous system. The brain and spinal cord are the main components of the central nervous system and the rest of the nerves from the brain connect to nerve tracts that extend throughout the body. The peripheral nervous system sends information from the body to the central nervous system for processing (x).

The nerves have a complex web of communication. Peripheral neuropathy occurs when something damages them and disrupts this communication. The peripheral nervous system contains sensory, motor and autonomic nerves. Sensory nerves control sensation, motor nerves control muscle strength and movement and autonomic nerves control digestion and cardiovascular functions. Each type of nerve damage may produce different symptoms (x).

What Causes Peripheral Neuropathy?

Peripheral neuropathy is caused by nerve damage that affects the nerves’ ability to relay electrical signals from the brain and spinal cord to other parts of the body. There are three different actions in the body that can disrupt this communication (x):

  • Normal signals getting lost
  • Signals being sent when they shouldn’t be
  • Complications that distort the messages

Most of the time peripheral neuropathy is either genetic or acquired, meaning the damage is either present at birth or the patient develops it later in life. If the condition is acquired, it may be a result of another disease or condition or it may be idiopathic with no identifiable cause (x).


The most common cause of peripheral nerve damage is physical injury, such as car accidents, falls, sports and medical procedures. If any of these activities stretch or compress the nerves, it can cause damage. If a patient has a broken or detached bone it may also cause damage to the nerves near the injury (x, x).


Diabetes is the most common cause of peripheral neuropathy and specifically polyneuropathy, meaning the patient suffers from damage to more than one nerve. Diabetic neuropathy causes pain, numbness and loss of sensation in the extremities. According to research, more than half of patients with diabetes have nerve damage, whether it is mild or severe. Diabetic neuropathy develops because high blood sugar and fat levels can put pressure on the nerves or damage the blood vessels, which provide oxygen to the nerves (x, x).

Other health conditions that may cause peripheral neuropathy include inflammation, kidney and liver disorders that cause toxin buildup, hypothyroidism and nutritional deficiencies (x).

Alcohol and Toxins

Excessive alcohol consumption is another common cause of peripheral neuropathy. Researchers have not identified the exact cause, but alcohol reduces essential nutrients from the body and if the patient is malnourished it can damage the nerves. According to research, ethanol, which is the active chemical in alcoholic drinks, is toxic to the nerve cells (x). In addition, exposure to toxins can also cause peripheral neuropathy, such as heavy metal poisoning from substances like arsenic, lead or mercury (x, x).

Infections & Autoimmune Diseases

Infections can also damage nerve tissues and cause peripheral neuropathy, such as Varicella-zoster virus which causes (chickenpox, shingles), herpes simplex virus, Epstein-Barr virus, Lyme disease and human immunodeficiency virus (HIV) (x).

In some cases, a patient may have an autoimmune disease that only affects the nerves instead of the entire body. Usually this type of autoimmune disease results from a recent infection. In other cases, a patient may have a systemic autoimmune disease in which the immune system attacks healthy cells throughout the body. The disease may target the nerves directly or it can damage tissue that puts pressure on the nerves. For example, Sjögren’s syndrome, lupus and rheumatoid arthritis may cause peripheral neuropathy (x).

Cancer & Chemotherapy Drugs

Specific types of cancer may cause nerve damage or tumors may put pressure on the nerve fibers. In addition, a rare group of degenerative disorders called paraneoplastic syndromes cause an immune response that causes nerve damage in cancer patients. Further, some patients undergoing chemotherapy or radiation therapy may develop peripheral neuropathy. However, only certain drugs cause nerve damage and only about 30 to 40 percent of patients get it (x).

Causes of Peripheral Neuropathy

Signs of Peripheral Neuropathy

A patient’s symptoms depend on the type of nerves that the condition damages because each type of nerve performs a different role in the body.

Motor Nerve Damage

Motor nerves control muscle movement and allow the body to consciously control actions like walking and talking. The main symptom that motor nerve damage causes is weak muscles. Patients may also experience (x):

  • Painful muscle cramps
  • Uncontrollable muscle twitching which is visible under the skin

Autonomic Nerve Damage

Autonomic nerves are responsible for regulating the organs to perform functions that humans do not control consciously like breathing and digestion. Damage to autonomic nerves may cause (x):

  • Excessive sweating
  • Heat intolerance
  • Gastrointestinal problems
  • Trouble eating or swallowing
  • Inability to control blood pressure

Sensory Nerve Damage

The sensory nerves are responsible for communicating messages that describe body sensations, such as touch, temperature or pain. Because these nerves’ functions is so wide, it can cause several different symptoms such as (x):

  • Inability to feel touch, specifically in the hands and feet 
  • Loss of reflexes and coordination, similar to motor nerve damage
  • Inability to feel pain or temperature changes
  • Hypersensitivity to pain and neuropathic pain, especially at night

Diagnosing Peripheral Neuropathy

To diagnose peripheral neuropathy, doctors first perform a physical exam and ask about the patient’s medical history. They may also conduct other tests to confirm the diagnosis. These tests include blood tests, a CT or MRI and a nerve biopsy (x). In addition, the patient may need an electromyography (EMG) or the doctor may perform a nerve conduction study. An electromyography determines how the muscles react to nerve signals, using small needle probes to measure the electrical signals moving in the muscles. In a nerve conduction study, the doctor places small electrodes on the patient’s skin to examine how the nerves transmit electrical signals (x).

Treating Peripheral Neuropathy

Treatment for peripheral nerve damage focuses on addressing the underlying cause, if the doctor can identify it. For example, patients may need surgery for conditions like carpal tunnel or a spinal cord tumor. Usually patients can control diabetic neuropathy by controlling their blood sugar levels. If it results from nutritional deficiencies, the patient may benefit from vitamin therapy and immunotherapy may help inflammatory neuropathy (x).

See Also

If doctors do not find a direct cause, they may recommend physical or psychological therapy, pain management techniques or medication to relieve some of the patients’ symptoms, such as tricyclic antidepressants and epilepsy medication (x).

Supplements for Brain Function

Patients may also opt for natural supplements to help support healthy brain function. Supplements will not treat peripheral neuropathy or any other health condition, but they may help improve overall health in conjunction with other medical treatments. Always consult a doctor before adding any supplement to a dietary regimen.

Alpha Lipoic Acid (ALA)

Alpha-lipoic acid is an antioxidant, meaning it can potentially help protect the nerve tissues from damage. One of its functions is improving diabetic neuropathy. Research states that it may also increase insulin sensitivity, which also plays a role in diabetes (x, x).

As a dietary supplement, the recommended serving size for ALA powder supplements is 600 mg up to two times a day with meals. Overdose or taking excessive amounts at a time may cause abdominal discomfort and acid reflux. Discuss ALA supplementation with a physician before adding it to a supplement regimen.

Acetyl L-Carnitine

Acetyl L-carnitine can help support metabolism by facilitating the breakdown of fatty acids into energy. In addition, it is loaded with antioxidants that may help neutralize free radicals that can cause damage to the nerves (x). The suggested serving size for acetyl L-carnitine supplements is 500 mg one to three times per day. Consult a doctor before taking this supplement.

N-Acetyl L-Cysteine

According to research, N-acetyl L-cysteine can fortify the immune system so that it can fight infections or other types of damage in the body. NAC may also help boost mood and cognitive functions (x). As a dietary supplement, the recommended dosage for N-acetyl L-cysteine powder supplements is 600 mg one to three times per day. Consult a health professional before supplementing with NAC, if you have a history of heart conditions or blood sugar problems.

Fish Oil

Fish oil is a common supplement for its potential benefits on cardiovascular health. Fish oil may also help patients maintain a healthy weight and blood cholesterol levels (x). Studies state that it may also have a positive effect on diabetic neuropathy (x). The recommended dosage for 1,000 mg fish oil softgels is one to two softgels two or three three times per day, with approval from a doctor.

Bottom Line

Peripheral neuropathy results from damage to the peripheral nervous system. It may be caused by injuries, infections, autoimmune diseases, alcoholism and exposure to toxins that interfere with the messages that the brain sends throughout the body. Peripheral neuropathy can affect the sensory, autonomic and motor nerves. Because each type of nerve has a different function, damage to different nerves causes different effects on the body.

Treatment options for peripheral neuropathy differ depending on what causes the damage, if doctors can identify a specific cause. For example, patients with diabetic neuropathy may improve by monitoring and controlling blood sugar levels. Doctors may also prescribe medications to manage pain or recommend physical or psychological therapy. Patients may also be able to take natural supplements to support brain function and improve overall health, such as fish oil, N-acetyl cysteine and acetyl L-carnitine. However, they are not a cure for peripheral neuropathy or any other condition. Instead, they aim to help improve overall health. Always consult a doctor before taking any dietary supplement.

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