Peripheral nerves are the nerves outside of the brain and spinal cord. They relay information between the central nervous system (CNS), and all other parts of the body. The brain and spinal cord are part of the CNS.
Polyneuropathy affects several nerves in different parts of the body at the same time. In cases of mononeuropathy, just one nerve is affected.
Polyneuropathy can affect nerves responsible for feeling (sensory neuropathy), movement (motor neuropathy), or both (sensorimotor neuropathy).
It may also affect the autonomic nerves responsible for controlling functions such as digestion, the bladder, blood pressure, and heart rate.
Although the exact number of people with polyneuropathy is not known, the National Institute of Neurological Disorders and Stroke (NINDS) estimate that approximately 20 million people in the United States have some form of peripheral neuropathy, and most of them have polyneuropathy.
Types of polyneuropathy
There are more than 100 types of peripheral neuropathy, and most of these are polyneuropathies.
Each type is classified according to the type of nerve damage, the underlying cause, and the symptoms that it produces.
There are three main patterns of polyneuropathy:
- Chronic symmetrical peripheral neuropathy: Most polyneuropathies are chronic and develop over many months.
- Multiple mononeuropathy: There is damage to at least two separate nerve areas.
- Acute symmetrical peripheral neuropathy: This is rare. The most common cause is Guillain-Barré syndrome, a condition that can be fatal.
Some neuropathies can take years to develop, but others become severe within hours to days of onset.
Causes and risk factors
A variety of medical conditions and other factors can cause polyneuropathy, including:
- Diabetes: This can be a significant risk factor, especially if blood glucose levels are poorly controlled. One study of more than 1,400 people with type 2 diabetes found that every fifth person had diabetic neuropathy.
- Alcohol abuse: Alcohol can damage nerve tissue, and alcohol abuse is often associated with nutritional deficiencies that contribute to neuropathy.
- Autoimmune conditions: The immune system attacks the body, causing damage to nerves and other areas. Conditions include Sjogren’s syndrome, celiac disease, Guillain-Barré syndrome, rheumatoid arthritis, and lupus.
- Bacterial or viral infections: Certain infections can lead to neuropathy, including Lyme disease, shingles, hepatitis B, hepatitis C, and HIV.
- Bone marrow disorders: Examples of these include abnormal proteins in the blood, some forms of bone cancer, and lymphoma.
- Exposure to toxins: Toxic neuropathy may be caused by exposure to industrial chemicals such as arsenic, lead, mercury, and thallium. Drug or chemical abuse is also a risk factor.
- Hereditary disorders: Certain conditions, such as Charcot-Marie-Tooth disease, are forms of hereditary neuropathy.
- Hypothyroidism: An underactive thyroid may lead to polyneuropathy, although this is uncommon.
- Kidney disease: Uremic neuropathy is a form of polyneuropathy that affects 20 percent to 50 percent of people with kidney disease, according to the Center for Peripheral Neuropathy.
- Liver disease: Research indicates that peripheral neuropathy is very common in those with cirrhosis of the liver.
- Medications: Chemotherapy, along with some drugs used to treat HIV/AIDS, can cause neuropathy.
- Poor nutrition: Deficiencies of vitamins B-1, B-6, B-12, and E may lead to polyneuropathy, as these are vital for nerve health.
- Physical trauma or injury: Repetitive motion such as typing, accidents, or other injuries can damage peripheral nerves.
Some cases of polyneuropathy have no known cause. These are known as idiopathic neuropathy.
Polyneuropathy can produce a variety of symptoms, depending on which nerves are affected.
Symptoms associated with sensory or motor nerve damage can include:
- pins and needles
- difficulty using the arms, legs, hands, or feet
- increased pain (such as burning, stabbing, freezing, or shooting pains)
- sleep problems due to night-time pain
- inability to feel pain
- extreme sensitivity to touch
- inability to sense temperature changes
- lack of coordination
- increased episodes of falling
- changes to the skin, hair, or nails
- foot and leg ulcers
- skin and nail infections
- muscle weakness
- muscle twitching
Symptoms associated with autonomic nerve damage include:
- heat intolerance
- unusual sweating
- bladder problems or incontinence
- digestive problems
- blood pressure or pulse abnormalities
- difficulty eating or swallowing
- difficulty breathing
- inability to sense temperature changes
- lack of coordination
Other conditions with similar symptoms
Fibromyalgia and polyneuropathy may have similar symptoms, but the cause of fibromyalgia is unknown.
Similarities also exist between multiple sclerosis and peripheral neuropathy.
Conditions associated with polyneuropathy
There are many conditions associated with polyneuropathy, including:
- celiac disease
- Charcot-Marie-Tooth Disease
- Guillain-Barré Syndrome
- hepatitis B
- hepatitis C
- kidney disease
- liver disease
- Lyme disease
- osteosclerotic myeloma
- pernicious anemia (vitamin B-12 deficiency)
- rheumatoid arthritis
- Sjogren’s syndrome
Common complications associated with polyneuropathy include:
- Falls and injury: A lack of balance and coordination, along with muscle weakness, can lead to an increase in falls and injuries sustained from falls.
- Burns and skin damage: Numbness and an inability to feel pain or temperature changes can lead to accidental burns, cuts, and other damage to the skin.
- Infections: Injuries, burns, and cuts, particularly on the legs and feet, can go unnoticed, leading to an increased risk of infection.
Diagnosis is based upon medical history, a physical exam, and neurological evaluation. Depending on the person’s symptoms, tests may be ordered.
The doctor will take a detailed review of all symptoms, lifestyle factors, and family history.
They will also check the patient’s height, weight, pulse, blood pressure, and temperature. The heart, lungs, and abdomen may also be checked to rule out alternative physiological causes.
Blood tests may be ordered to check for diabetes, thyroid function, immune function, nutrient deficiencies, and other factors that may cause polyneuropathy.
There may be some simple tests to check reflexes, muscle strength, sensitivity to temperature and other sensations, coordination, and posture.
Other tests that may be used in the diagnosis of polyneuropathy include:
- MRI or CT scan: These imaging techniques look for tumors, herniated disks, or other abnormalities that may be affecting nerve function.
- Electro-diagnostic tests: These non-invasive tests measure the electrical activity in the muscles and nerves, helping to detect nerve damage. Examples are electromyography and nerve conduction velocity.s
- Biopsies: The doctor may remove a small portion of a nerve, or sample of the skin, to test for abnormalities in nerve function or nerve endings.
The American Academy of Family Physicians recommend that peripheral neuropathy treatment address the underlying disease process, correct nutritional deficiencies, and aim to provide relief from symptoms.
Available treatments include medication, medical therapies and procedures, and alternative treatments.
Several different medications are available to treat neuropathy and its symptoms. These include:
- Medications for associated conditions: Conditions that may be causing polyneuropathy should be managed through various treatments, including medication if recommended by a doctor. Examples include insulin for diabetes and thyroid hormones for hypothyroidism.
- Pain medications: Over-the-counter pain relief can be beneficial for those with mild to moderate pain. These medications should not be taken on a long-term basis.
- Prescription medications: Some antidepressants, such as a group of medications called TCAs (including amitriptilyne or nortriptilyne), can be used, and another group called SNRIs, such as duloxetine, may also help. Corticosteroid injections could possibly be used for mononeuropathies, and some seizure medications such as gabapentin or pregabalin may help.
A variety of medical procedures are available. They include:
- Transcutaneous electrical nerve stimulation: Electrodes send a gentle current of electricity through the skin. This can help with pain and sensitivity.
- Plasma exchange: People with inflammatory or autoimmune conditions may benefit from this therapy. The practitioner removes blood from the body, then separates antibodies and other proteins from the blood, before returning the blood to the body.
- Immune globulin therapy: Those with inflammatory and autoimmune conditions are given high levels of proteins to act as antibodies, which helps with immune function.
- Physical therapy: People with muscle weakness or coordination issues may find physical therapy helpful.
- Orthotic and other devices: Braces, canes, casts, splints, walkers, and wheelchairs may provide support and pain relief to those with neuropathy of the hands, feet, legs, and arms.
If neuropathy is caused by pressure on a nerve, surgery may be recommended.
Alternative and complementary treatments may offer relief to some people with polyneuropathy. Examples include:
- chiropractic care
However, these remedies have not been widely studied.
Prevention and outlook
Preventing polyneuropathy involves limiting the risk factors and managing underlying conditions. A person with polyneuropathy may not be able to avoid all risk factors, but some lifestyle choices may reduce the risk. These are:
- avoiding alcohol
- avoiding exposure to toxins, including cigarette smoke
- limiting factors that contribute to physical trauma or injury, such as repetitive actions and restrictive positions
- getting enough sleep and physical activity to support immune function
- eating a balanced diet rich in vitamins and minerals
- considering vitamin B-12 supplements if a vegan or vegetarian
Managing underlying conditions
Managing any underlying conditions can help to prevent the onset of the condition. Those with diabetes and other conditions related to polyneuropathy should closely follow the treatment plan devised by their doctor, as well as ensure that they attend all check-ups.
The outlook for polyneuropathy varies and can depend on the underlying cause, which nerves are damaged and the extent of the damage.
For some people, treating the underlying cause can lead to improvements. For others, the damage is permanent. In some cases, symptoms may get worse over time.
When to see a doctor
If any of the symptoms of polyneuropathy are experienced such as weakness, pain, or tingling in the hands or feet it is important to see a doctor.
Implementing a treatment plan as soon as possible is important to manage symptoms and prevent further nerve damage.