Polyneuropathy

Acute polyneuropathy has many causes:

The cause of chronic polyneuropathy is often unknown. Known causes include the following:

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:

Polyneuropathy may result from damage to any of the following:

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.

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:

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:

Specific treatment of polyneuropathy depends on the cause, as for the following:

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.