What is the Difference between Peripheral Neuropathy and Complex Regional Pain Syndrome?

Elliot T. Udell, DPM

In podiatry, when we talk about peripheral neuropathy we generally are referring to conditions that affect the local nerves in the lower extremity. This is distinct from conditions that affect the brain and/or spinal cord Diabetes is one of the leading causes of peripheral neuropathy. Research shows that diabetes affects the tiny nerves and small arteries in the area where the patient is experiencing pain. The pain is generally described as "severe burning" or "pins and needles" and is generally worse at night. Months or years later, this pain may lead to numbness indicating the presence of far greater nerve damage, and in such cases we have to be concerned with the development of ulcerations.

Complex regional pain syndrome (CRPS), also known as reflex sympathetic dystrophy syndrome (RSD), presents quite differently. Because my practice is focused on patients with severe foot and ankle pain syndromes, I treat people with both peripheral neuropathy and CRPS/RSD. Hence, I am well aware of the overt as well as subtle differences between these conditions.

People with CRPS/RSD generally present with a history of an inciting injury, which may be a sprain, fracture or even surgery (many elective surgical procedures can lead to CRPS/RSD). They also present with severe pain, which is far more intense than that experienced by people with peripheral neuropathy. The pain is so severe at times that even air blowing on the area can cause a person to wince in distress. People who have CRPS/RSD can also present with other symptoms generally not associated with peripheral neuropathy, such as sleep disturbances and clinical depression. The depression results from the physiology and anatomy of the sympathetic nervous system synapses rather than purely from an emotional reaction to the pain. Moreover, we commonly see skin problems associated with CRPS/RSD, such as edema and small shiny plaques that are exquisitely painful.

Another significant difference is the tendency of non-treated CRPS/RSD to progress to the opposite extremity and to the upper limbs. A glance at the anatomy of the sympathetic nervous system, which runs parallel up and down both sides of the spinal cord with perpendicular crosses from right to left, may explain why this illness can easily progress to other parts of the body. Also, CRPS/RSD patients often have both spasms of the muscle and progressive muscle weakness. Untreated, this muscle weakness can lead to atrophy and loss of use of the extremity. Such extensive and debilitating muscle weakness, as well as atrophy, is not common in peripheral neuropathy.

Because the anatomy and physiology of the symptoms are different, so are the treatments of these conditions. The treatment of CRPS/RSD is complex; we use intense physical medical modalities and many different types of oral pain medications and antidepressants. Each condition is different, challenging, and time consuming, but the rewards of seeing patients leave their wheel chairs and crutches and return to work and school makes any effort we put into working with these people emotionally rewarding.

Dr. Elliot Udell specializes in pain management of the foot and ankle. He is in practice in Hicksville, New York. He is currently president of the American Society of Podiatric Medicine and is on the board of the American Society of Podiatric Dermatology. He is board certified in Podiatric Primary Care as well as Pain Management. He lectures at medical seminars throughout the US as well as in Europe. He can be reached at Suite 206, 120 Bethpage Road, Hicksville, New York 11801 Tel: (516) 935-1113, [email protected]

10/15/2005