Nerves are an integral part of body function – carrying messages from the brain to the rest of the body and back again. Something as simple as lifting a finger would not be possible if the message to do so was not carried by nerves from the brain to the hand. And serious injury could occur if the nerves sensing heat or pain were unable to convey a warning back to the brain. The three main nerves affecting hand, finger and thumb movement include the radial, median, and ulnar nerves.
The nerve fiber and its insulation are fragile and often damaged by excessive stretching, pressure or cutting – disrupting the conveyance of necessary information and proper muscle function.
Stretching or pressure related injuries may cause the fibers carrying the information to falter and prevent the nerve from working, without damaging its insulating cover. When nerve fibers are cut but the insulation remains undamaged, the end farthest from the brain dies – while a recovery process starts at the end closest to the brain. When both the nerve fiber and its insulation are cut, a recovery process does not begin automatically. In fact, a small mass may form at the end of the cut – forming a nerve scar, or neuroma. A neuroma can be painful and may even cause an electrical sensation when touched.
Those at Risk
Because there are many possible causes of nerve injury, there is no specific patient profile. Such injuries commonly involve falls, collisions, motor vehicle accidents, fractures, gunshot wounds, and cuts – or other forms of penetrating trauma.
Determining which nerves have been affected in an injury involves an assessment that includes; the type of injury and affected area, patient history, the location of pain during hand movement, the loss of strength in the muscle supplied by the suspected nerve, and the location of numbness and loss of hand, finger or thumb function. Other signs of innervation deficiencies may be evident in the skin – as dry, shiny skin that does not wrinkle when immersed in water is the result of skin denervation. The severity of damage and grade of injury is determined with electrodiagnostic testing.
Treatment will depend on the location and severity of the injury, as well as the type of activities and work in which patients are involved in daily life. It can range from supportive therapy to maintain range of motion and muscle tone, to a minimally invasive end-to-end suture closure, or surgical repair procedure appropriate for the type of damage the nerve and surrounding area sustained.
For simple nerve injuries, the nerve may be repaired immediately. If a wound is “dirty” or crushed and more complex – possibly involving a number of other injuries as well – nerve repair may take place following the repair of the other injured sites and later assessment of scar tissue development.
The end result and recovery depends on the age of the patient, the type of wound and nerve involved, as well as the location of the injury. But, targeted physical therapy always improves the chances of patients resuming normal function.