John D. England, MD, Professor and Chairman of Neurology at LSU Health Sciences Center New Orleans School of Medicine, is the principal investigator of two studies recommending new testing guidelines for neuropathy – a common degenerative nerve disorder that to this time had few evidence-based standards for evaluation and management. The studies, published in two separate papers in the December 3, 2008 online issue of Neurology®, resulted in recommendations about who should be tested, when, and how. The researchers found that a combination of certain screening laboratory blood tests and other specialized testing, including autonomic, genetic, as well as skin biopsies, yielded definitive information for certain forms of the disorder, while nerve biopsies may not be as useful in certain cases.
"There are many people with a neuropathy who have been walking around for years without having been diagnosed and treated," said guidelines lead author John D. England, MD, Professor and Chairman of the Department of Neurology at Louisiana State University Health Sciences Center New Orleans School of Medicine and Fellow of the American Academy of Neurology. "Both neurologists and people with neuropathy need to know that the appropriate choice of tests is critical to accurate diagnosis."
Neuropathy is a disorder of the peripheral nervous system. More than a hundred types have been identified. It may be genetic or acquired, and different nerves can be involved producing different symptoms and levels of damage. According to the National Institutes of Health, in the most common forms of polyneuropathy (multiple nerve involvement), the nerve fibers (individual cells that make up the nerve) most distant from the brain and the spinal cord malfunction first. Pain and other symptoms often appear symmetrically, for example, in both feet followed by a gradual progression up both legs. Next, the fingers, hands, and arms may become affected, and symptoms can progress into the central part of the body. Many people with diabetic neuropathy experience this pattern of ascending nerve damage. Some people may experience temporary numbness, tingling, and pricking sensations , sensitivity to touch, or muscle weakness. Others may suffer more extreme symptoms, including burning pain (especially at night), muscle wasting, paralysis, or organ or gland dysfunction. People may become unable to digest food easily, maintain safe levels of blood pressure, sweat normally, or experience normal sexual function. In the most extreme cases, breathing may become difficult or organ failure may occur.
Neuropathy affects one in 50 people in the general population and one in 12 over the age of 55. The most common cause is diabetes. Other common causes are heredity, alcohol abuse, poor nutrition and autoimmune processes. Not all of the causes are known.
To develop the guidelines, the authors analyzed all available scientific studies on the topic.
The guidelines recommend that doctors obtain certain blood tests for all patients with numb, painful feet.
"People with suspected nerve problems should talk to their doctors about screening tests, especially blood glucose, vitamin B12 level and serum protein levels, since these tests can often point to common causes of neuropathy," said Dr. England.
The guidelines recommend tailored genetic testing for accurately diagnosing certain neuropathies that run in families. They further recommend that doctors consider a combination of specialized tests to accurately evaluate neuropathies with autonomic dysfunction. Autonomic nerves regulate biological activities that people do not control consciously, such as breathing, digesting food, blood pressure and heart rate, and gland functions. Skin biopsy may also be useful to diagnose loss of tiny nerve fibers in the skin.