What is Peripheral neuropathy?

Peripheral neuropathy is nerve damage that affects the peripheral nervous system (PNS). It can cause symptoms such as pain, loss of sensation or inability to control muscles. In practical usage, the term “peripheral neuropathy” is used interchangeably with the term “neuropathy,” which indicates any type of nerve damage. Peripheral neuropathy is very common. As many as 20 million Americans have neuropathy, according to The Neuropathy Association.

The nervous system controls virtually all activity in the body, including breathing, thinking and movement. It is divided into two parts. The brain and spinal cord make up the central nervous system (CNS), which processes information from the senses and responds with commands to the muscles and glands in the body. The second part of the nervous system is called the peripheral nervous system. The PNS includes the autonomic nervous system (ANS), which is not under a person's conscious control.

The nerves of the PNS relay information from the brain and spinal cord (the CNS) to various points in the body. In addition, the PNS relays information from the body back to the CNS. For example, the PNS may send sensory information back to the CNS indicating that a person's feet are cold, which would then trigger a response from the CNS to take steps to warm the feet. Damage to PNS nerves can short-circuit these messages, preventing them from being sent at all or causing them to be sent at the wrong time or too slowly.

Peripheral neuropathy may occur as a result of damage to a single nerve (mononeuropathy) but is more likely to include multiple nerves (polyneuropathy). In some cases, two or more isolated nerves in separate areas of the body may be affected (mononeuritis multiplex).

Peripheral neuropathy causes various levels of discomfort depending on which nerves are affected and the extent of damage to the nerves. The most common symptoms of peripheral neuropathy are weakness, numbness, tingling and pain, which can be mild to severe. Because motor and sensory axons run in the same nerve bundle, damage to a specific nerve bundle typically affects both motor and sensory functions.

Neuropathies are rarely life-threatening unless other diseases are complicating factors.

Types and differences of peripheral neuropathy

More than 100 types of peripheral neuropathy have been identified. Each has its own symptoms and prognosis, which are dependent on the type of nerves affected – autonomic, motor or sensory.

Peripheral neuropathies are generally classified as being acute or chronic. Acute neuropathies involve symptoms that appear suddenly, that progress rapidly and that subside slowly as the nerves begin to heal. In contrast, chronic neuropathies feature symptoms that emerge subtly and unfold gradually over time. People with chronic neuropathies may see their symptoms progress, or may experience discomfort that eventually plateaus. In other cases, symptoms may go into remission, only to re-emerge in the future.

Types of peripheral neuropathies include:

How is it diagnosed?

Diagnosing peripheral neuropathy can be difficult, because symptoms can vary so much from person to person. In addition, it can be very difficult to determine exactly what type of neuropathy a patient has. A physician typically will compile a thorough medical history and perform a complete physical examination of the patient. In addition, a neurological examination is often performed.

Various tests may be performed to pinpoint the cause of a patient's peripheral neuropathy. For example, blood tests may reveal the presence of diabetes, liver or kidney dysfunction, or vitamin deficiencies. A spinal tap may be used to look for abnormal antibodies in a patient's cerebrospinal fluid that my indicate neuropathy. Imaging tests such as computed axial tomography (CAT scan) and magnetic resonance imaging (MRI) also may be helpful.

Other tests that may be performed include:

A physician also may test a patient's muscle strength or ability to perceive touch, temperature and pain. Underlying conditions responsible for peripheral neuropathy may be revealed through additional testing for cardiovascular disease, connective tissue disorders and malignancies.

How is Peripheral neuropathy treated?

Acquired neuropathies (i.e., those that are not caused by inherited conditions) usually are best treated by addressing the underlying condition causing the nerve damage. In some cases, surgery may be helpful, such as when a nerve is compressed due to an entrapment injury. An examples of such a surgery is a carpal tunnel syndrome release. There is no cure for most inherited neuropathies.

If the condition itself cannot be cured, symptoms associated with peripheral neuropathy may be reduced or eliminated through various therapies. Over-the-counter analgesics can be used to treat mild neuropathies. Anticonvulsants, antidepressants and anesthetics also may be used.

Use of certain devices such as wheelchairs, hand or foot braces and splints can either help compensate for muscle weakness or alleviate nerve compression. In some cases, orthopedic shoes can help people with gait problems. Mechanical ventilation can aid the breathing of patients with severe forms of neuropathy.

As long as the nerve cell itself has not been destroyed, peripheral nerves have the ability to regenerate. This may be helped by physical therapy or occupational therapy. Physical therapy includes a mixture of exercises, massage and other treatments to maintain strength and flexibility. Occupational therapy is similar to physical therapy, but it focuses on improving patients' fine motor skills.

Other steps that can help a person relieve symptoms associated with neuropathies include:

• Avoiding toxin exposure
• Limiting alcohol consumption
• Restoring proper vitamin levels
• Quitting smoking

Maintaining good health is often the best defense against the damage of neuropathies. This includes maintaining a healthy weight, engaging in regular exercise and eating a well-balanced diet.

In addition, patients often are advised to take various measures to increase their safety, which may help prevent certain injuries that can cause peripheral neuropathy. Safety measures may include installing railings and adequate lighting and removing potentially dangerous obstacles (e.g., loose rugs). Patients are urged to avoid placing prolonged pressure on the body's pressure points, such as elbows and knees. Pressure in these areas can result in additional nerve damage.

Medications

Pamelor (Nortriptyline), Tegretol (Carbamazepine), Cymbalta (Duloxetine), Lyrica (Pregabalin), Dilantin (Phenytoin), Ultram (Tramadol)

Activity

• If peripheral neuropathy is interfering with normal activities, physical therapy may help.
• If you have difficulty maintaining balance, walk with a cane or other support.
• Install rails next to the bathtub.

Diet

No special diet. Vitamin and mineral supplements probably will be necessary. Pyridoxine (vitamin B-6) may help.

What might complicate it?

If the cell bodies of the damaged nerves have been destroyed, functional loss (sensory loss or muscle weakness) may become permanent.

Predicted outcome

If damaged nerve cell bodies have not been destroyed, and treatment of the underlying cause has been successful, full recovery from neuropathy is possible.

Alternatives

Peripheral neuropathy is a general finding of the physical exam and is not a specific diagnosis. It must be differentiated from other possible diseases.

Appropriate specialists

Neurologist and neurosurgeon.

Last updated 4 July 2015