Have you ever felt pain or numbness in your hands, legs or feet? This can be caused by a condition called peripheral neuropathy (PN), a form of nerve damage.
PN is relatively common-about 20 million Americans have it and most people associate it with diabetes. But there are literally hundreds of forms of PN.
The condition can be caused by athletic injuries, repetitive motions and autoimmune diseases. Continual pressure on one part of the body (from using crutches, for example) or a ligament compression (such as carpal tunnel syndrome) also can cause PN, as can exposure to toxic chemicals. Even hormonal changes in women could be the cause.
What you need to know…
Hundreds Of Causes
About one-third of neuropathy patients also have diabetes. And up to 70% of people with diabetes will eventually develop PN. Elevated blood sugar damages vessels carrying blood to the extremities, causing PN. The highest risk for PN is in people who have had diabetes for at least 25 years.
Other causes of PN…
- Nerve entrapment injuries. Activities involving repetitive motions-for example, typing, working a cash register or riding a bike-are a common cause of nerve inflammation and damage. You should suspect a local injury if you have symptoms in just one area (mononeuropathy). Patients who have diabetes or other systemic diseases are more likely to have damage to multiple nerves (polyneuropathy).
- Vitamin B-12 deficiency damages the coating that surrounds and protects nerves the myelin sheath), which can lead to PN. Between 10% and 25% of older adults are deficient in B12 because of an age-related decline in intrinsic factor, a protein that's needed for absorption of the vitamin.
- Autoimmune diseases (such as lupus and rheumatoid arthritis) can cause the immune system to attack and damage the myelin sheath. Nerve damage also can be caused by conditions such as kidney disease, hypothyroidism, hepatitis C and Lyme disease.
- Toxic neuropathy, usually caused by chemotherapy during cancer treatments, can result in severe nerve damage. Additionally, exposure to environmental chemicals, such as heavy metals or agricultural pesticides, can cause PN.
Although pain is often a symptom of PN, many patients with the condition experience uncomfortable but painless sensations, including tingling, itching and/or numbness. For example, most patients who have diabetic neuropathy experience foot numbness rather than pain-in fact, some cannot feel their feet at all.
Warning: Pain, tingling, numbness or burning sensations in the feet may be the first sign of diabetes.
Difficult To Detect Root Cause
Most cases of PN can be diagnosed in a doctor's office with simple tests, including reflex and manual muscle testing, along with "touch tests" that can identify a loss of sensation in a particular location.
You also might need nerve conduction studies, which determine how fast the nerves can carry the signal and how well the muscles can respond to it, or electromyography, which helps distinguish nerve damage from muscle-related disease. In addition, your doctor might order blood tests to check for infection, hormone deficiencies or nutritional status.
The catch: Even though it's usually easy to identify PN, it can be a challenge to find the underlying cause. In nearly one-third of cases, the cause is never determined. In these patients, treatments can only relieve symptoms, and damage to the nerve or nerves will probably continue because the mechanism can't be identified. Research is under way to try to find solutions.
Recovery Is Possible
The good news is that the majority of patients with PN will gradually heal once the underlying cause is identified and treated although it could take years before the nerves fully recover.
Example: Patients with diabetes who improve their glucose control will frequently experience a reduction in neuropathy symptoms over a period of months, but it might take a year or longer before their symptoms are mainly or completely gone.
The odds for making a complete recovery improve when the nerve damage is recent and treatment is started quickly.
Example: The nerve will completely regenerate in most patients with carpal tunnel syndrome if they're diagnosed and surgically treated within six months.
Important: Go to a doctor right away if you suspect that you have PN. The longer you wait, the higher the risk that you'll have permanent nerve damage—and a lifetime of pain and/or other undesirable symptoms.
Best Treatments Now
The current treatments available for PN only relieve discomfort--they do not affect the ability of nerves to regenerate. Scientists are developing medications that specifically target nerve pain and improve the ability of nerves to heal, but these drugs are still in the experimental stage. For now…*
- Don't depend on aspirin, ibuprofen or related medications. They are not very effective for PN-and the potential side effects (such as gastrointestinal bleeding and kidney or liver damage) make them a poor choice for most patients.
- Tricyclic antidepressants, such as nortriptyline (Aventyl, Pamelor) or desipramine (Norpramin, Pertofrane), are an effective treatment for PN, particularly when the nerve discomfort is caused by diabetes. Taken at low doses, they reduce pain even in patients who don't suffer from depression. Side effects, which may include a dry mouth and constipation, are somewhat rare.
Also helpful: Selective serotonin and norepinephrine reuptake inhibitors (SSNRIs), such as duloxetine (Cymbalta). Side effects may include nausea.
- Gabapentin (Neurontin) and pregabalin (Lyrica). First developed for seizures, they change electrical activity in the brain and reduce pain caused by many types of PN, including the pain caused by cancer and cancer treatments.
Bonus: Pregabalin reduces anxiety in some patients-helpful because stress and anxiety often increase due to chronic pain. Possible side effects include dizziness, sedation and sometimes cognitive impairment in older adults. Side effects can be reduced, however, by starting patients on a low dose that's increased over a period of weeks.
- Topical lidocaine (such as Lidoderm and Topicaine) used in patch or gel form is a good choice for patients whose painful neuropathy is limited to specific, localized areas. Even at high doses (three patches daily, applied for a total of 12 hours), little of the drug enters the bloodstream, which reduces risk for side effects. A local rash where the gel/patch is applied may occur in some patients.
- Opioid painkillers, such as oxycodone (OxyContin) and levorphanol (Levo-Dromoran), can be effective for reducing neuropathic pain. However, many doctors avoid them because they cause sedation and could lead to addiction. These drugs are mainly used for patients with severe pain who do not respond to other treatments. In addition to sedation and dependency, side effects may include nausea and constipation.
*Tell your doctor if you take other medications to avoid possible interactions