Peripheral nerves are the nerves that exit the spinal cord (in the center of the spine) to feed the rest of the body. They typically branch out into smaller and smaller sections to feed various areas. There are specifically defined areas that the peripheral nerves feed, and an injury to one of these nerves usually occurs in a clearly defined pattern. Injuries to the peripheral nerves can occur in a variety of fashions.
Traction injuries occur when the nerve is pulled beyond its normal flexibility, causing inflammation and sometimes tearing of nerve fibers. For example, this can happen in the upper body when the head is forced away from the shoulder or when the shoulder is forced down away from the head. Symptoms may include a burning pain down the arm that is worse when the head is tipped away from the arm.
Crush injuries occur when something crushes the nerve such as a blunt object or when a muscle surrounding the nerve constricts the nerve from contracting continuously on the nerve. When this occurs in the buttock muscle, the sciatic nerve can get constricted, known as sciatica. With sciatica, one typically feels pain from the center of the buttock down the back of the thigh and sometimes even down to the foot. Treatments include releasing the pressure on the nerve which may mean relaxing the muscle that is constricting the nerve, or it may mean changing how we sit to get the pressure off the nerve, or possibly improving our low back and pelvis alignment to reduce pull on the nerve. In the worst case scenario, one may need surgery to make room for the nerve as it passes out of the spine or buttock region.
Lastly, the nerve can become severed such as when we cut ourselves, or when one experiences an amputation. In any of these types of peripheral nerve injuries, our brain becomes disconnected from the area fed by the nerve, and we may lose feeling and the ability to move the area fed by the nerve. It is important to seek medical attention immediately if there are signs of loss of feeling or use in order to have the best possible chance of repairing the nerve. Phantom limb syndrome occurs when someone who has had a limb amputated still feels the limb. It is thought that reflexive firing of our nerves continues and continues to light up areas of the brain previously attached to the limb.
Our bodies can re-grow/repair peripheral nerves at the rate of about 1 centimeter per month; as long as the new nerve doesn’t get lost on its way to its final destination.
To learn more about how messages are carried from our body along our peripheral nerves, and how our nerves change in response to pain, click on all about pain.