Hand and Wrist

Nerve Injuries

Anatomy

Similar to electrical wiring, nerves are part of the system that carries messages between the brain and the rest of the body. Motor nerves relay messages between the brain and muscles to make the body move. Sensory nerves send messages between the brain and different parts of the body to signal pain, pressure and temperature. Nerves are composed of fibers, or axons, that are separated into bundles. The nerve, and each bundle of axons within the nerve, is surrounded with a covering of insulation made up of layers of protective tissue.

Description

Injury to a nerve can stop signals to and from the brain, resulting in a loss of feeling in the injured area and causing the muscles to stop working properly.

Causes

Nerves are fragile and can be damaged by pressure, stretching, or cutting. When an injury causes fibers within the nerve to break without damaging the protective insulation, the end farthest from the brain dies while the end closest to the brain may eventually begin to heal, growing new fibers beneath the protective tissue until reaching a muscle or sensory receptor. The nerve grows about 1mm per day so it can take many months to reach the damaged area and may take a year to resume working. When both nerve and cover are severed but not properly treated, the growing nerve fibers may form a painful nerve scar, or neuroma.

Surgery

During surgery, the protective insulation around both ends of the injured nerve is sewn together so that new fibers can grow and the nerve can work again. If there has been a loss of nerve that has resulted in a space between the ends, it may be necessary to graft a piece of nerve from a donor part of your body to make the repair. This could cause a permanent loss of feeling in the area where your donor graft is taken.

Once the nerve's protective covering is repaired, it usually takes three or four weeks for the nerve to begin healing. Depending on your age and other factors, you can expect the nerve to grow approximately one inch per month. With an injury to a nerve in the arm above the fingertips, it may be as long as a year before your fingertips regain feeling. During recovery, it is common to experience a sensation of pins and needles in your fingertips. You may find this uncomfortable, but it usually passes and it is a sign of healing.

Recovery and Therapy

Several things can be done to keep up muscle activity and feeling while waiting for the nerve to heal. While you're waiting for the nerve to heal, physical therapy will help maintain muscle activity and feeling, and keep your joints flexible and prevent them from becoming stiff. If you've injured a sensory nerve there will be no feeling in the affected area, so great care must be taken not to burn or cut your fingers. After your nerve has recovered, sensory re-education may be necessary to improve sensation in the hand or finger. Age, type of wound and nerve, and location of the injury are all factors that in your recovery. Although nerve injuries may create lasting problems for the patient, care by a physician and proper therapy help two out of three patients return to more normal use.