neuropathy

It is caused by the deterioration of the nerves that lead to the ends of the limbs (hands and feet). This makes it impossible for the body and spinal column to communicate with the muscles , bone and other tissue that makes up the upper and lower extremity.

The peripheral nervous system is the body’s “electrical wiring system”. Any disruption in this system will cause foot pain symptoms such as burning, tingling, numbness, itchiness, and occasional shooting pains all the way to unremitting pain. Peripheral neuropathy will also lead to an abnormal gait and eventual breakdown of the feet due to the inability of the body to “feel” the ground that you are walking on. If left untreated peripheral neuropathy can lead to permanent loss of nerve function, tissue damage and muscle atrophy.

Peripheral neuropathy can be caused by disease; nerve compression, entrapment, or laceration; exposure to toxins; or inflammation. In many cases, especially in people over the age of 60, no cause can be determined.

Early intervention is very important in treating neuropathy. Identifying the source of the neuropathy and rectifying the problem, if possible, will go a long way to eliminating the worst cases of neuropathy. Many sources of neuropathy are not treatable, but symptomatic relief of the neuropathy can be achieved. Medication induced neuropathy, although rare is one type of neuropathy where once the offending medication is removed, the symptoms of neuropathy will subside. This is also true of toxic induced neuropathy, where exposure to a toxic agent is causing the peripheral neuropathy.

Some of the more common medications known to cause neuropathy include statin drugs, colchicine, allopurinol, Taxol (a chemotherapeutic agent for ovarian and breast cancer), Amiodarone (an anti-arrhythmic drug), some antibiotics and even thalidomide which has come back into vogue for treatment of HIV related ulcers.

Neuropathy can be a consequence of dose regulation of the various drugs, in certain cases considered a minor side effect in an effort to fight a more potent disease, eg: cancer.

Other causes of neuropathy include:

• alcoholism
• metabolic disorders
• autoimmune disorder
• cancer
• chronic kidney failure
• rheumatoid arthritis
• infectious disease such as lyme disease
• vitamin deficiencies
• liver failure
• radiculopathy
• diabetes

The two most common forms of neuropathy that I see are diabetic neuropathy (See my discussion on neuropathy and the diabetic foot) and radiculopathy, which is a neuropathy that originates from the nerve roots as they come out of the spinal column. Pressure on the nerve from any number of sources as the nerve comes out of the spinal column can cause an adverse neurological event in the feet.

In instances where there has been trauma such as in a car accident or a fall the diagnosis is somewhat easier to make; it becomes much more difficult in the older individual where the radiculopathy is the result of degenerative arthritis of the spine. The picture can be further clouded when symptoms of neuropathy are actually the result of poor circulation as seen in older individuals.

Treatment is geared to the finding the cause of the neuropathy. As stated earlier many causes of neuropathy cannot be remedied so treatment becomes symptomatic. Treatment options for reducing pain include physical therapy, injection therapy, surgical intervention (tarsal tunnel, decompression spinal surgery) oral and topical medication.

Along the lines of decompression surgery (where the tissue surrounding the affected nerve is removed to take pressure off the nerve) there is a school of thought that neuropathy that is often diagnosed as diabetic neuropathy may actually be compression neuropathy. It has been theorized that peripheral nerves in diabetics "swell" more than non-diabetics and that the swelling of these nerves puts excessive pressure on the nerves as they pass thru tight spaces in the leg and foot. Such would be the case with tarsal tunnel where the tibial nerve, once swollen, is trapped on the inside of the foot below the ankle resulting in neuropathic symptoms.

Further proof of this theory would be the fact that tarsal tunnel counterpart in the wrist known as carpal tunnel is much more prevalent in diabetics.

The idea here is for your doctor to rule out tarsal tunnel and other lower extremity nerve entrapments first before making a diagnosis of diabetic neuropathy and going forward with oral medication.

Cymbalta is an FDA approved medication for neuropathy. Side effects include constipation, diarrhea, headaches, dry mouth , nausea and dizziness. Neurontin, although not FDA approved is an off label use for neuropathy. Side effects include low blood pressure, dizziness, drowsiness and fatigue.

Additionally, lidocaine patches applied locally may also relieve the symptoms of neuropathy. Side effects include lightheadedness, dizziness and drowsiness.

A topical preparation called capsaicin has been used with some degree of success. Made from a pepper derivative, when applied topically to the affected area a few times a day, over the course of a few weeks many patients begin to feel a reduction in their symptoms.

Recent research has suggested that some nutritional supplements may help reduce neuropathic pain. Specifically acetyl l-carnitine, 600mg. per day has demonstrated the ability to reduce neuropathic symptoms in some individuals. This supplement will probably have to be taken for a couple of months before any relief is noticed.

In the November, 2006 issue of "Diabetes Care" reference is made to the benefits of alpha-lipoic acid in oral doses for the reduction of diabetic neuropathy. Various doses were tested but it was found that a once daily dose of 600 mg. was enough to see relief in as little as two weeks. The nutritional supplement was effective in reducing the stabbing and burning symptoms of neuropathy but had little effect on numbness.

"Whether the observed favorable short-term effect of ALA on neuropathic symptoms and deficits can be translated into slowing the progression of diabetic polyneuropathy in the long term is unknown," the authors write. (Dr. Dan Ziegler from Heinrich Heine University, Duesseldorf, Germany and colleagues) "However, our finding that neuropathic deficits such as impaired sensory function were improved is encouraging, because these are major risk factors in the development of neuropathic foot ulcers."