Peripheral neuropathy, a result of damage to the nerves located outside of 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.
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).
Peripheral neuropathy can happen for many reasons. These include –
• Type 2 diabetes. The most common cause of peripheral neuropathy is uncontrolled Type 2 diabetes. When your blood sugar is too high for too long, it damages your peripheral nerves. That’s why people with Type 2 diabetes can lose feeling in their feet and lower legs.
• Alcohol use disorder. Excessive intake of alcohol, especially over long periods of time, can damage nerves. Alcohol use disorder is a common cause of peripheral neuropathy, and it can also contribute to vitamin deficiencies that lead to peripheral neuropathy.
• Vitamin and nutrient deficiencies. People can develop nerve damage because they have deficiencies in certain vitamins. The deficiencies that are most likely to cause this are copper and vitamins B1, B6, B9, B12, folic acid (B9) and E. Too much vitamin B6 can also cause this.
• Autoimmune and inflammatory conditions. Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy (CIDP) can cause severe weakness. They’re also very treatable. Neuropathy can happen due to lupus, rheumatoid arthritis, Sjögren syndrome, vasculitis and more.
• Medications and toxins. Chemotherapy and certain other medications (antibiotics, and medications that treat arrhythmia and gout) can cause peripheral neuropathy. Exposure to some heavy metals and industrial chemicals can also cause it.
• Tumors. Malignant tumors (cancer) and benign (noncancerous) tumors can both disrupt your peripheral nervous system.
• Genetic conditions. Genetic conditions are ones you inherit from one or both parents. Examples of these causing peripheral neuropathy include amyloidosis, Fabry disease and Charcot-Marie-Tooth disease.
• Infections. Nerve damage from infections can happen because of viruses, such as HIV, or bacteria — such as Borrelia burgdorferi, which causes Lyme disease. Another common example is having shingles, which can lead to lingering nerve pain.
• Hansen disease (better known as leprosy). While the effects of this disease — which is rare in developed countries — are most visible on the skin, it also damages your peripheral nerves.
• Trauma and surgery. Injuries and damage directly to nerves can happen from trauma or from medical procedures. Swelling or stretching can also damage nerves. This kind of damage is usually only in one location. It can be long-term or even permanent.
• Vascular disorders (circulation-related problems). Lack of blood flow can cause peripheral neuropathy. A harmless, temporary form of this happens when you sit or lay a certain way and an arm or leg falls asleep. This goes away quickly if you shift position enough for circulation to return.
• Idiopathic neuropathy. It’s common for peripheral neuropathy to happen for unknown reasons. This type of neuropathy is known as “idiopathic” or “cryptogenic” (hidden or obscure cause).
Risk Factors –
Peripheral neuropathy risk factors include –
• Diabetes, especially if your sugar levels are poorly controlled
• Alcohol misuse
• Vitamin deficiencies, particularly B vitamins
• Infections, such as Lyme disease, shingles, Epstein-Barr virus, hepatitis B and C, and HIV
• Autoimmune diseases, such as rheumatoid arthritis and lupus, in which your immune system attacks your own tissues
• Kidney, liver or thyroid disorders
• Exposure to toxins
• Repetitive motion, such as those performed for certain jobs
• Family history of neuropathy
Complications of peripheral neuropathy can include –
• Burns and skin injuries. You might not feel temperature changes or pain on parts of your body that are numb.
• Infection. Your feet and other areas lacking sensation can become injured without your knowing. Check these areas regularly and treat minor injuries before they become infected, especially if you have diabetes.
• Falls. Weakness and loss of sensation may be associated with lack of balance and falling.
The most common types of tests for peripheral neuropathy (either to confirm the diagnosis or rule out other conditions) include –
• Blood tests (these can detect many problems, ranging from immune system problems to toxins and poisons, especially metals like mercury or lead).
• Nerve ultrasound.
• Nerve biopsy.
• Genetic testing.
• Magnetic resonance imaging (MRI).
Treatment either targets the underlying cause, or it aims to provide symptomatic pain relief and prevent further damage. Treatments may include –
• Maintaining nerve health by keeping a healthy lifestyle. This can include exercising, eating healthy, keeping a healthy weight, correcting any vitamin deficiencies, and not drinking alcohol or smoking.
• Managing blood sugar in cases of diabetic neuropathy, to prevent further nerve damage.
• Taking immunosuppressive drugs when the cause is an autoimmune disorder, or using plasmapheresis, a procedure that cleans the blood to reduce inflammation.
• Removing the exposure to a suspected toxin, or stopping a problematic drug, to halt further nerve damage.
• Using hand and and foot braces or orthopedic shoes to help cope with physical disability from motor symptoms.
Medications for neuropathic pain
Medications that may help relieve symptoms, but do not cure the problem, include –
• drugs normally used for epilepsy, such as carbamazepine
• antidepressants, such as venlafaxine
• Duloxetine, which may help people with chemotherapy-induced neuropathy.
• prescription skin patches, such as Lidoderm, for temporary, localized pain relief. This contains the local anesthetic lidocaine. The patches are like bandages, and a person can cut them to size.
• non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, which may help control milder pain. These are available over the counter.
• Topical ointments and creams, such hot pepper-containing capsaicin, which may also ease pain. A person can also get patches.
Non-drug measures for peripheral neuropathy can include using warm or cold packs, unless heat or cold makes the symptoms worse.
Stress relief and other complementary therapies include meditation, relaxation techniques, massage, and acupuncture. These may help a person cope with pain from the condition.
Some of the possible causes of peripheral neuropathy are preventable. You can also lower your chances of developing it by preventing or delaying certain conditions. In general, the best preventive or precautionary steps you can take include –
• Eating a balanced diet. Certain vitamin deficiencies, especially vitamin B12 deficiency, can affect your nervous system and cause major problems. Other vitamins, especially B6, are toxic and cause peripheral neuropathy at high levels.
• Staying physically active and maintaining a healthy weight. This, along with managing your diet, can help prevent or delay the onset of Type 2 diabetes, which damages your peripheral nerves over time.
• Wearing safety equipment as needed. Injuries are a major source of nerve damage. Using safety equipment during work and play activities can protect you from these injuries or limit how severe the injuries are.
• Managing chronic conditions as recommended. If you have a chronic condition that can affect your peripheral nerves, especially Type 2 diabetes, it’s important to manage it as your healthcare provider recommends. That can limit the effects of the condition or delay how long it takes to get worse.
• Avoiding alcohol in excess. Excessive consumption of alcohol is a proven cause of peripheral neuropathy. You can reduce your risk of neuropathy (and some other medical complications) by avoiding alcohol, or consuming it in moderation only.
• Avoiding exposures to toxins, poisons and heavy metals. Heavy metals like lead and mercury can cause severe damage to your nervous system. Mercury exposure is rare thanks to environmental regulations, but older thermometers or thermostats may still contain it. Older homes may also contain lead-based paint. Local, state and national agencies may have resources and services to help you avoid exposure to toxic metals and chemicals. If you work around such metals and chemicals, follow all safety regulations and use recommended or required protective gear.
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