Infections, toxins, drugs, cancers, nutritional deficiencies, diabetes, autoimmune disorders, and other disorders can cause many peripheral nerves to malfunction.
Sensation, strength, or both may be impaired, often in the feet or hands before the arms, legs, or trunk.
Doctors base the diagnosis on results of electromyography, nerve conduction studies, and blood and urine tests.
If treating the underlying disorder does not relieve symptoms, physical therapy, drugs, and other measures may help.
(See also Overview of the Peripheral Nervous System Overview of the Peripheral Nervous System The peripheral nervous system refers to the parts of the nervous system that are outside the central nervous system, that is, those outside the brain and spinal cord. Thus, the peripheral nervous... read more .)
Polyneuropathy may be
Acute (beginning suddenly)
Chronic (developing gradually, often over months or years)
Causes of Polyneuropathy
Acute polyneuropathy has many causes:
Infections involving a toxin produced by bacteria, as occurs in diphtheria Diphtheria Diphtheria is a contagious, sometimes fatal infection of the upper respiratory tract caused by the gram-positive, rod-shaped bacteria (see figure How Bacteria Shape Up) Corynebacterium diphtheriae... read more
An autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more (when the body attacks its own tissues), as occurs in Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is a form of polyneuropathy causing muscle weakness, which usually worsens over a few days to weeks, then slowly improves or returns to normal on its own. With treatment... read more
Certain toxins, such as triorthocresyl phosphate (TOCP) and thallium
The cause of chronic polyneuropathy is often unknown. Known causes include the following:
Infections (such as hepatitis C Hepatitis C, Acute Acute hepatitis C is inflammation of the liver that is caused by the hepatitis C virus and that lasts from a few weeks up to 6 months. Hepatitis C is spread through contact with blood or other... read more , HIV infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and can cause acquired immunodeficiency syndrome (AIDS). HIV is transmitted... read more , Lyme disease Lyme Disease Lyme disease is a tick-transmitted infection caused by Borrelia species, primarily by Borrelia burgdorferi and sometimes by Borrelia mayonii in the United States. These... read more , shingles Shingles Shingles is a painful skin rash caused by a viral infection that results from reactivation of the varicella-zoster virus, the virus that causes chickenpox. What causes the virus to reactive... read more )
Autoimmune disorders (such as chronic inflammatory demyelinating polyneuropathy Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) Chronic inflammatory demyelinating polyneuropathy is a form of polyneuropathy that, like Guillain-Barré syndrome, causes increasing muscle weakness, but the weakness progresses for more than... read more , vasculitis, and systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more )
Vitamin B12 deficiency Vitamin B12 Deficiency Vitamin B12 deficiency can occur in vegans who do not take supplements or as a result of an absorption disorder. Anemia develops, causing paleness, weakness, fatigue, and, if severe, shortness... read more , which also causes subacute combined degeneration of the spinal cord Subacute Combined Degeneration Subacute combined degeneration is progressive degeneration of the spinal cord due to vitamin B12 deficiency. Nerve fibers that control movement and sensation are damaged. People have general... read more and often pernicious anemia Vitamin B12 Deficiency Vitamin B12 deficiency can occur in vegans who do not take supplements or as a result of an absorption disorder. Anemia develops, causing paleness, weakness, fatigue, and, if severe, shortness... read more
Other nutritional deficiencies (such as thiamin deficiency Thiamin Deficiency Thiamin deficiency (causing beriberi and other problems) is most common among people whose diet mainly consists of white rice or highly processed carbohydrates in countries with high rates of... read more ), an uncommon cause in the United States, except among alcoholics who are malnourished
Toxic substances, including heavy metals such as arsenic, lead Lead Poisoning Lead poisoning affects many parts of the body, including the brain, nerves, kidneys, liver, and blood. Children are particularly susceptible because their nervous system is still developing... read more and mercury
Cancer (such as multiple myeloma Multiple Myeloma Multiple myeloma is a cancer of plasma cells in which abnormal plasma cells multiply uncontrollably in the bone marrow and occasionally in other parts of the body. People often have bone pain... read more ), which damages nerves by directly invading or putting pressure on them
Drugs, including the antiseizure drug phenytoin, some antibiotics (such as chloramphenicol, nitrofurantoin, and sulfonamides), and some chemotherapy drugs (such as vinblastine and vincristine)
The most common form of chronic polyneuropathy usually results from poor control of blood sugar levels in people with diabetes but may result from excessive use of alcohol.
Diabetic neuropathy refers to the several forms of polyneuropathy that diabetes can cause. (Diabetes can also cause mononeuropathy Mononeuropathy Mononeuropathy is damage to a single peripheral nerve. Pressure on a nerve for a long time is the most common cause of mononeuropathy. The affected area may tingle, feel prickly, or be numb... read more or multiple mononeuropathy Multiple Mononeuropathy Multiple mononeuropathy is the simultaneous malfunction of two or more peripheral nerves in separate areas of the body. It causes abnormal sensations and weakness. (See also Overview of the... read more , which leads to weakness, typically of the eye or thigh muscles.)
Some people have a hereditary form of polyneuropathy Hereditary Neuropathies Hereditary neuropathies affect the peripheral nerves, causing subtle symptoms that worsen gradually. (See also Overview of the Peripheral Nervous System.) Hereditary neuropathies may affect... read more .
Depending on the cause, polyneuropathies may affect the following:
Motor nerves (which control muscle movement)
Sensory nerves (which transmit sensory information)
Cranial nerves (which connect the head, face, eyes, nose, certain muscles, and ears to the brain)
Autonomic nerves (which control involuntary functions such as blood pressure and heart rate)
A combination of the above
Polyneuropathy may result from damage to any of the following:
Myelin sheath Insulating a Nerve Fiber (the membranes that surround the axon and that enable nerve impulses to travel quickly), as occurs in Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is a form of polyneuropathy causing muscle weakness, which usually worsens over a few days to weeks, then slowly improves or returns to normal on its own. With treatment... read more
The blood supply to the nerve, as can occur in vasculitis Overview of Vasculitis Vasculitic disorders are caused by inflammation of the blood vessels (vasculitis). Vasculitis can be triggered by certain infections or drugs or can occur for unknown reasons. People may have... read more (inflammation of blood vessels)
Symptoms of Polyneuropathy
Symptoms of polyneuropathy may appear suddenly (acute, occurring over a few days to a couple of weeks) or develop slowly and occur over a period of time (chronic, occurring over months to years) depending on the cause.
Acute polyneuropathies (as occurs in Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is a form of polyneuropathy causing muscle weakness, which usually worsens over a few days to weeks, then slowly improves or returns to normal on its own. With treatment... read more or with toxins) often begin suddenly in both legs and progresses rapidly upward to the arms. Symptoms include weakness and a pins-and-needles sensation or loss of sensation. The muscles that control breathing may be affected, resulting in respiratory failure.
Many chronic polyneuropathies affect sensation primarily. Usually, the feet are affected first, but sometimes the hands are. A pins-and-needles sensation, numbness, burning pain, and loss of vibration sense and position sense (knowing where the arms and legs are) are prominent symptoms. Because position sense is lost, walking and even standing become unsteady. Consequently, muscles may not be used. Eventually, they may weaken and waste away. Then, muscles may become stiff and permanently shortened (called contractures).
Diabetic neuropathy commonly causes painful tingling or burning sensations in the hands and feet—a condition called distal polyneuropathy. Pain is often worse at night and may be aggravated by touch or by a change in temperature. People may lose the senses of temperature and pain, so they often burn themselves and may have open sores caused by prolonged pressure or other injuries. Without pain as a warning of too much stress, joints are susceptible to injuries. This type of joint injury is called neurogenic arthropathy (Charcot joints Neurogenic Arthropathy Neurogenic arthropathy is caused by progressive joint destruction, often very rapid, that develops because people cannot sense pain, continually injure joints, and thus are not aware of the... read more ).
Polyneuropathy often affects the nerves of the autonomic nervous system Overview of the Autonomic Nervous System The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious... read more , which controls involuntary functions in the body (such as blood pressure, heart rate, digestion, salivation, and urination). Typical symptoms are constipation, sexual dysfunction, and fluctuating blood pressure—most notably a sudden fall in blood pressure when a person stands up (orthostatic hypotension Dizziness or Light-Headedness When Standing Up In some people, particularly older people, blood pressure drops excessively when they sit or stand up (a condition called orthostatic or postural hypotension). Symptoms of faintness, light-headedness... read more ). The skin may become pale and dry, and sweating may be reduced. Much less often, control of bowel movements or urination is lost, leading to fecal or urinary incontinence.
People who have a hereditary polyneuropathy (such as Charcot-Marie-Tooth disease Charcot-Marie-Tooth Disease Charcot-Marie-Tooth disease is a hereditary neuropathy in which the muscles of the lower legs become weak and waste away (atrophy). Charcot-Marie-Tooth disease affects nerves that control muscle... read more ) may have hammer toes, high arches, and a curved spine (scoliosis Scoliosis Scoliosis is abnormal curvature of the spine. Scoliosis can be present at birth or can develop during adolescence. Mild forms may cause only mild discomfort, but more severe forms can cause... read more ). Abnormalities in sensation and muscle weakness may be mild. Affected people with mild symptoms may not notice the symptoms or may consider them unimportant. Other people are severely affected.
How completely people recover depends on the cause of polyneuropathy.
Diagnosis of Polyneuropathy
A doctor's evaluation
Electromyography and nerve conduction studies
Blood and urine tests to determine the cause
Doctors usually recognize polyneuropathy by the symptoms. A physical examination can help doctors diagnose polyneuropathy and identify the cause.
Electromyography and nerve conduction studies Electromyography and Nerve Conduction Studies Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more are usually done, particularly in the legs and feet. These tests may be used to do the following:
Confirm that a polyneuropathy is present
Determine how severe it is
Determine whether motor nerves, sensory nerves, or a combination are involved
Determine what type of damage is causing the problem—for example, whether the myelin sheath around nerves is damaged (called demyelination Overview of Demyelinating Disorders Most nerve fibers inside and outside the brain are wrapped with many layers of tissue composed of a fat (lipoprotein) called myelin. These layers form the myelin sheath. Much like the insulation... read more )
After polyneuropathy is diagnosed, its cause, which may be treatable, must be identified. Doctors ask whether other symptoms are present and how quickly the symptoms developed. This information may suggest possible causes.
Blood and urine tests may detect a disorder that is causing polyneuropathy, such as diabetes, kidney failure, or an underactive thyroid gland.
Sometimes a nerve or muscle biopsy is necessary.
Sometimes polyneuropathy affecting the hands and feet is the first indication that people have diabetes.
Sometimes, when extensive testing detects no obvious cause, the cause is a hereditary neuropathy that affects other family members so mildly that the disorder was never suspected.
If weakness is widespread and rapidly worsening, doctors do other tests:
A spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more (lumbar puncture) is done to obtain a sample of cerebrospinal fluid, which surrounds the brain and spinal cord. If the protein level in the fluid is high and few or no white blood cells are present, the cause may be an autoimmune disorder that causes demyelination, such as Guillain-Barré syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is a form of polyneuropathy causing muscle weakness, which usually worsens over a few days to weeks, then slowly improves or returns to normal on its own. With treatment... read more .
Treatment of Polyneuropathy
Treatment of the cause
Relief of pain
Sometimes physical and occupational therapy
Specific treatment of polyneuropathy depends on the cause, as for the following:
Diabetes Treatment Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. Urination and thirst are... read more : Careful control of blood sugar levels may slow progression of the disorder and occasionally relieves symptoms. Transplantation of islet cells Pancreas Transplantation Pancreas transplantation is the removal of a healthy pancreas from a recently deceased person or rarely a part of a pancreas from a living person and its transfer into person with severe diabetes... read more (cells that produce insulin), located in the pancreas, is sometimes done and may cure the diabetes and lessen the neuropathy.
Multiple myeloma Treatment Multiple myeloma is a cancer of plasma cells in which abnormal plasma cells multiply uncontrollably in the bone marrow and occasionally in other parts of the body. People often have bone pain... read more , liver failure Treatment Liver failure is severe deterioration in liver function. Liver failure is caused by a disorder or substance that damages the liver. Most people have jaundice (yellow skin and eyes), feel tired... read more , or kidney failure Treatment Acute kidney injury is a rapid (days to weeks) decline in the kidneys’ ability to filter metabolic waste products from the blood. Causes include conditions that decrease blood flow to the kidneys... read more : Treatment of these disorders may result in slow recovery.
Cancer Surgery for Cancer Surgery is a traditional form of cancer treatment. It is the most effective in eliminating most types of cancer before it has spread to lymph nodes or distant sites (metastasized). Surgery may... read more : Surgically removing the cancer may lessen the neuropathy
Autoimmune disorders Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more : Treatments include corticosteroids, drugs that inhibit the immune system (immunosuppressants), plasma exchange Plateletpheresis (platelet donation) In addition to normal blood donation and transfusion, special procedures are sometimes used. In plateletpheresis, a donor gives only platelets rather than whole blood. Whole blood is drawn from... read more (filtering of toxic substances, including abnormal antibodies, from the blood), and immune globulin (a solution containing many different antibodies collected from a group of donors) given by vein (intravenously).
Drugs and toxins: Stopping the drug or avoiding exposure to the toxin can sometimes reverse the polyneuropathy. Antidotes are available for certain drugs and toxins and can reverse some toxic effects.
Excessive amounts of vitamin B6: If the vitamin is stopped, polyneuropathy may resolve.
If the cause cannot be corrected, treatment focuses on relieving pain and problems related to muscle weakness. Physical therapy sometimes reduces muscle stiffness and can prevent muscles from shortening and becoming stiff. Physical and occupational therapists can recommend useful assistive devices.
Some drugs that are usually not considered pain relievers can lessen pain due to nerve damage Neuropathic Pain Neuropathic pain is caused by damage to or dysfunction of the nerves, spinal cord, or brain. (See also Overview of Pain.) Neuropathic pain may result from Compression of a nerve—for example... read more . They include the antidepressant amitriptyline, the antiseizure drugs gabapentin and pregabalin, and mexiletine (used to treat abnormal heart rhythms). Lidocaine, an anesthetic applied as a lotion, an ointment, or a skin patch, may also help.