Feeling 'Pins and Needles' Is a Circulation Problem

Think of that pins and needles feeling as a traffic jam in your nervous system.

When traffic is running smoothly, tiny electrical impulses move along the nerves that run from your arms and legs to your spine. These sensations then move up the spinal cord to the brain.

But by putting sustained pressure on a nerve, you create a roadblock that prevents the nervous system from carrying the electrical impulses that normally transmit feeling.

While the nerve is compressed, so are the arteries that feed blood to the nerve. The nerve can't function for long without a supply of its nutrients mainly oxygen and glucose. Shutting off the nerve's signals or its blood supply causes a limb to fall asleep.

Because of the close relationship between nerves and arteries, having a limb fall asleep and then feeling pins and needles is more common in people with poor circulation, says Harold Brody, M.D., distinguished professor emeritus of pathology and anatomical sciences at the State University of New York at Buffalo.

For example, elderly persons or people in wheelchairs who sit for long periods of time are more prone to nerve "traffic jams." When the blockage is removed, the nerve cells begin waking up as they start receiving impulses again. You begin to feel those uncomfortable pins and needles. The nervous system tends to become hyperactive as nerves regain sensation.

The nerve structures, as they recover, tend to be irritable for a period of time. That's because the nerves are firing spontaneously. Most of the time, the irritability -- the feeling of pins and needles -- is a good sign, a temporary phase that means nerves are coming back to life.

In some cases, however, a nerve may be seriously injured, perhaps in an accident. Then the nerve may get stuck in a pins-and-needles stage and the person may experience continuous pain. A good example is carpal tunnel syndrome. In this instance, pins and needles are a danger signal. But most often, pins and needles is just an odd but harmless sensation that we feel from time to time.