Painful polyneuropathy is a relatively common syndrome, characterized by a painful numbness or burning in the hands or feet. In more severe cases, the pain spreads over time to the arms, legs or trunk, leading to muscle weakness. It is usually caused by damaged peripheral nerve.
In general, there are two types of pain:
Nociceptive Pain – Normal, every day acute pain is a response to bodily injury. Nerves send signals to the brain that something is wrong. This type of pain is known as nociceptive pain and it serves to warn us of potential harm or injury. The nerves here are working normally and the pain resolves when the injury heals.
Neuropathic Pain – In this type of pain, it is the nerves themselves that are injured. Nerves misfire and cause pain, even in the absence of bodily injury. The pain can become chronic and is known as neuropathic pain. Painful polyneuropathy is a type of neuropathic pain.
Painful polyneuropathy has a wide variety of causes including diabetes, kidney failure, alcoholism, AIDS and Chemotherapy. How they cause nerve damage is not known. In general, there is either damage to nerve fibers or to the myelin sheath that surrounds them.
Performing a careful history and physical exam and correlating these with knowledge of the causes best makes the diagnosis. There are special tests known as electrodiagnostic tests that are sometimes helpful in making the diagnosis. Despite a thorough investigation, the cause is unknown in 25 to 50% of all cases.
If the underlying cause is known, then overall treatment of the cause is the best place to start. Medicines that have been found to be helpful seem to act on the nervous system. These include antidepressants (elavil, pamelor), anti seizure medications (neurontin), antisympathetic nervous system medications (clonidine) and steroids. Topical medicines including capsaisin, lidocaine and EMLA creams have been found to be helpful in some patients. Other therapies include nerve blocks, acupuncture, TENS, Spinal Cord Stimulation and relaxation techniques.
Treatment for this and other forms of chronic pain begins with a trust relationship between the physician and patient. In getting to know the patient, unique medical and social situation and life-effects of the pain, the right combination of therapies can be better determined.