Could that foot pain be neuropathy? Chronic pain, tingling, or numbness in your hands or feet could signal nerve damage from prediabetes or diabetes.(diabetic neuropathy)

If you have persistent shooting, tingling, or stabbing pain in your hands or feet that tends to get worse at night, or numbness in your feet, you could have a condition called peripheral neuropathy. The problem stems from nerve damage that causes nerves to become overexcited, firing off too many pain signals to the brain. When the damage becomes severe, the peripheral nerves lose the ability to respond to sensation, so people do not feel pain or injuries.

But clinical trials of investigational treatments now being conducted at New York Presbyterian-Weill Cornell Medical Center may provide ways to prevent or even reverse some of the damage.

Damaged nerves

There are many causes for neuropathy, but the most common cause is diabetes, explains Thomas Brannagan, MD, director of the Diabetic Neuropathy Research Center and associate professor of clinical neurology at the Weill Medical College of Cornell University. The condition, also known as diabetic sensorimotor polyneuropathy (DSP), is most common in diabetics with poorly controlled blood sugar and those who have had diabetes for more than 10 years.

"In diabetic neuropathy, high blood glucose may damage blood vessels that supply the nerves, and there is some evidence that high glucose can actually damage nerve cells directly. It's likely a multifactorial process," explains Dr. Brannagan. "The majority of people with diabetic neuropathy actually do not have pain. They lose the ability to feel pain, usually in their feet; this is usually how it comes to medical attention."

Neuropathy can affect people with shingles (herpes zoster), in which the chicken pox virus become reactivated in the body and affects nerves that supply certain areas of the skin. This is called post-herpetic neuralgia.

People with other forms of peripheral neuropathy can experience excruciating pain due to excessive nerve firing. In some cases, people can be so sensitive that even the feel of a soft cloth shirt on their skin can be painful. That's because damaged nerves "are like wires without insulation, they can start sparking on their own, creating a spontaneous generation of sensations to the brain," explains Sean Mackey, MD, PhD, associate director of the Stanford University Pain Management Center in Stanford, California. "It is these sensations the brain interprets as pain," he told a recent briefing in Washington. "The feeling of pain or tingling depends on the signal strength and the brain's threshold for interpreting these signals." (For information on another nerve disorder, see FYI on page 12.)