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Peripheral Neuropathy
What is peripheral neuropathy?
Neuropathy is a term for damage to nerve tissue that can result in a range of symptoms, including burning pain, tingling sensations, muscle weakness and loss of sense of touch in the hands and feet.
Neuropathy isn't a disease in itself but rather is a consequence of underlying medical problems. The most common cause of neuropathy is diabetes, but neuropathy can be associated with a range of medical issues, from alcoholism and poor nutrition to environmental toxins, herniated vertebral discs and Lyme disease. About one-third are idiopathic, or have no identifiable cause.
Neuropathy can affect the functioning of internal organs such as the heart, bladder and digestive systems, but the term is most often used to describe problems in the hands and feet peripheral neuropathy. And even peripheral neuropathy can be a broad term, encompassing, as examples, carpal tunnel syndrome that occurs in the wrist as a repetitive use injury and the system-wide damage of Guillain-Barrι syndrome, in which the body's own immune system destroys nerve's insulating sheaths, sometimes leading to paralysis and even respiratory failure.
It's estimated that some 22 million Americans deal with neuropathy from one cause or another. The frequency of neuropathy increases with age, and is estimated to affect as many as four percent of people over the age of 55.
This article focuses on peripheral neuropathy, or neuropathy in the legs and feet, and on the ways in which your Connecticut Surgical Group podiatrists can help you deal with problems that exist and prevent new ones.
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What is the make-up of the nervous system?
The nerves are the passageways for the signals that connect our brains to the rest of our bodies, carrying electrical impulses that provide the brain with sensory input from, say, our hands and feet, and sending the messages that tell the muscles in those hands and feet what to do. As you may expect from that description there are different kinds of nerves sensory nerves, motor nerves and the autonomic nerves that regulate our involuntary body functions like heartbeat, digestion and breathing.
A nerve is made up of cells called neurons, which include a cell body and a tail-like extension called an axon, which is coated with a myelin sheath that insulates the nerve fiber and helps in transmitting electrical signals. Anatomically, the body's nerves are grouped into two systems the central nervous system (CNS) that encompasses the brain and spinal cord, and the peripheral nerves that run from the CNS to the muscles, skin and internal organs throughout the body.
The nerves that serve the feet and legs are the longest nerves in the body, which may explain why symptoms such as pain and tingling often appear first in the feet and then progress up the legs. In some cases, the symptoms may occur in the hands first and move up the arms.
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What are the types of neuropathy?
Neuropathy can occur as mononeuropathy, in which a single peripheral nerve is damaged, or polyneuropathy, in which a number of nerves throughout the body are affected.
Mononeuropathy often results from a physical trauma that causes compression of a nerve, from prolonged repetitive motion such as working on an assembly line or clicking a computer mouse, or as a result of prolonged pressure that might result from an event such as extended confinement to bed.
Polyneuropathy is by far a more common form of neuropathy, with causes that can range from exposure to toxic substances such as mercury and lead, certain medications (such as some drugs to treat cancer), alcoholism, poor nutrition (especially a deficiency of Vitamin B12), bacterial or viral infections, autoimmune diseases such as rheumatoid arthritis, kidney or liver disease, an underactive thyroid gland or an inherited disease such as Charcot-Marie-Tooth disease. As noted, the single most common cause is diabetes.
Cases that exhibit polyneuropathy tend to be symmetrical that is, symptoms show up approximately equally in both legs or arms, or both sides of the body.
Doctors often refer to cases of neuropathy as "acquired" (that is, brought on by an outside factor such as injury, infection or a disease such as diabetes), "inherited" (that is, brought on by a genetic defect, a less common cause), or "idiopathic" (that is, from an unknown cause).
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What are the symptoms of peripheral neuropathy?
The symptoms of neuropathy most often begin gradually and take a long time to develop. That said, it must be noted that some cases can come on very suddenly.
- Symptoms of damage to the sensory nerves often begin in the feet with a tingling or pins-and-needles sensation, numbness, or burning, pinching or stabbing pain.
- Your skin can become sensitive, with even a light touch being painful. You may experience a sensation of wearing gloves or socks, when in fact you're not.
- Sometimes, you may have an absence of sensation and not be able to feel anything opening the door to the risk of developing ulcers and the dangers of infection.
- Symptoms of damage to motor nerves may include weakness or paralysis in the muscles associated with those nerves, and difficulty in walking properly or doing simple chores with your hands.
- Although not a focus of this article, it is valid to note that symptoms of autonomic nerve damage can include dizziness upon standing from a seated or lying position (related to a drop in blood pressure), bowel, bladder or sexual function problems, and a lessened ability to perspire.
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What is diabetic neuropathy?
Diabetic neuropathy is a categorization doctors use for neuropathy that is associated with diabetes milletus, the single most common cause of peripheral neuropathy. Diabetes is estimated to be responsible for approximately one-third of all cases of peripheral neuropathy.
While the mechanism is not fully understood, neuropathy is a common consequence of diabetes because of the chronic risk of hyperglycemia, or elevated blood sugar levels that comes with diabetes. Increased blood sugar levels are believed to interfere with nerve cells' ability to transmit electrical signals. As a result, control of blood sugar through diet, exercise and insulin injections is a primary concern for diabetics.
Although diabetic neuropathy is described as a specific condition, the consequences and potential complications associated with it are similar to those of other forms of neuropathy such as tingling, pain, loss of sensation and difficulty walking. Because diabetics represent such a large population, strong attention is paid to foot care, the risk of wound development and the dangers of infections. However, these issues can apply to individuals experiencing peripheral neuropathy generally.
It should be noted that neuropathy problems in diabetics usually appear some 10 to 15 years after diagnosis of diabetes. Thus, attention to blood sugar levels, potential symptoms and establishing a relationship with a podiatrist early on are important in helping to catch and possibly prevent these problems.
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What is Charcot-Marie-Tooth disease?
Named after three French and English physicians who defined it, Charcot-Marie-Tooth disease is an inherited neuropathic disorder involving progressive atrophy of muscles in the legs and, to a lesser degree, the arms. Erosion of the myelin sheath that insulates nerves interferes with the electrical signals that control muscle movement.
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What risks does neuropathy represent?
Neuropathy obviously represents a range of potential problems, including pain, failure of coordination in walking and other activities, and muscle weakness and atrophy.
Loss of sense of feeling caused by neuropathy carries with it a risk that you might injure a foot without realizing it. A small injury even a simple blister or minor cut can become a serious wound problem in a short period, subject to infection that, untreated, could become life-threatening or could result in the need for amputation of the infected foot.
Such foot problems can range in nature from ulcers (open sores that seem unable to heal) to Charcot foot, a condition in which the foot becomes warped in shape as the bones disintegrate.
For all these reasons, diligent foot care that prevents and detects foot injury is important, including attention to footwear, regular inspection of your feet and seeking prompt treatment from your healthcare providers. For more information, see the accompanying articles on Diabetic Foot Care (click here) and Wound Care (click here).
The podiatrists of Connecticut Surgical Group have extensive experience in these problems, and are leaders in techniques of the care and treatment of neuropathy problems in the feet.
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How is neuropathy diagnosed?
The first step in diagnosing neuropathy is a careful examination by your doctor, including a medical history and several diagnostic tests. These are likely to include electromyography to assess electrical discharges in your muscles, electroneurography to see how your nerves conduct electrical signals, nerve and muscle biopsies, a blood test to determine Vitamin B12 levels, and possibly a spinal tap to look for infection or inflammation.
Neuropathy isn't so much a disorder in itself as a consequence of underlying disease, whether diabetes, disease of the kidneys or liver, exposure to toxic substances or other problems. Your care is likely to involve a range of clinicians representing multiple specialties, with treatment focused on both the underlying problem and the immediate neuropathic problems.
Your CSG podiatrist works closely with your other caregivers to help you manage your disease, and it is important that you establish a relationship with your podiatrist early on in the diagnosis of your disease (or appearance of symptoms if you haven't been diagnosed by someone else) so that he or she can monitor your foot health and intervene before any problems become serious issues.
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How is neuropathy treated?
Treatment of neuropathy problems involves two avenues treating the underlying problem and dealing with the symptoms of the neuropathy itself.
If, for example, the underlying cause is elevated blood sugar levels associated with diabetes milletus, then the goal is to bring those blood sugar levels under control through diet, exercise and, possibly, insulin injections.
Similarly, eliminating exposure to toxic substances, unfriendly drugs and alcohol abuse would be called for, as would treatment of infections, rheumatoid arthritis, kidney and liver disease and thyroid gland problems.
If a Vitamin B12 deficiency is identified as a problem, then that can be corrected through a program of injections and possibly vitamin supplements in your diet. In situations in which the neuropathy has resulted from a compressed nerve due to injury, a tumor or other causes, surgery may be necessary to relieve the cause. If confinement to a wheelchair or bed or repetitive activity is responsible, ergonomic or body mechanics measures can be taken.
Depending on the underlying problem, treatment can resolve symptoms, halt progression of the neuropathy, assist in managing it and possibly reverse damage.
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How are the pain and other consequences of neuropathy treated?
Pain associated with neuropathy can often be treated with a range of medications, beginning with over-the-counter pain relievers such as aspirin, ibuprofen (most commonly known under the brand names Advil and Motrin) and acetaminophen (most commonly known under the brand name Tylenol). Prescription anti-inflammatory pain relievers can be tried if over-the-counter medicines don't work.
If those approaches prove inadequate, a number of prescription medications used to treat depression have been shown to be effective in treating pain. These include, among others, desipramine (common brand name: Norpramine), amitriptyline (Elavil) and doxepin (Sinequan). While it's not entirely understood how these work in relieving pain, it's suspected that they increase levels of epinephrine and serotonin at nerve endings and therefore help lessen pain transmission. It is clear that the mechanism has very little to do with their roles as antidepressants.
Other medications that have been found useful in relieving some types of neuropathic include anticonvulsant drugs such as carbamazepine (Tegretol) and phenytoin (Dilantin), and topical ointments such as capsaicin (Capzasin and Zostrix).
Physical therapy to improve body mechanics and maintain muscle strength may be appropriate, as may TENS, transcutaneous electronic muscle stimulation. By delivering very small electrical impulses to nerve pathways, TENS may stop pain signals from reaching your brain. Other treatments such as acupuncture and relaxation and biofeedback therapies may be useful.
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What can I do to prevent neuropathy problems from developing or progressing?
The most important factor in preventing or managing existing problems with neuropathy is dealing with the underlying disease to eliminate development of neuropathic issues.
This means managing your blood sugar levels if you are diabetic, limiting alcohol consumption, or following your physician's guidance about your rheumatoid arthritis or other health problem. It also means following a healthy life-style generally, including eating a nutritious diet and exercising regularly.
If you have experienced any degree of loss of sensation in your feet, then you are at risk of developing problems from cuts, punctures and other wounds that you can't feel. Such a wound can develop into an ulcer (an open sore that seems unable to heal, a problem that can lead to potentially life- or limb-threatening infection. Damage to bone that is unnoticed can lead to Charcot foot, a condition in which the foot becomes warped in shape as the bones disintegrate
For all these reasons, diligent foot care that prevents and detects foot injury is important, including attention to footwear, regular inspection of your feet and seeking prompt treatment from your healthcare providers. For more information, see the accompanying articles on Diabetic Foot Care (click here) and Wound Care (click here).
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For additional information
You can find additional information about neuropathy at web sites sponsored by government agencies, professional societies and healthcare institutions. It should perhaps be noted that the World Wide Web is open to many sources posting questionable information and promises, and you are encouraged to seek information from established, reputable organizations.
Likely sources include:
The American Podiatric Medical Association
(www.apma.org)
The Neuropathy Association
(www.neuropathy.org)
The National Institute of Neurological Disorders and Stroke
(www.ninds.nih.gov)
The National Institute of Diabetes and Digestive and Kidney Diseases
(www.niddk.nih.gov)
The American Diabetes Association
(www.diabetes.org)
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