Traumatic Nerve Injuries
Traumatic nerve injuries often leave the patient with significant disability. There are 3 major nerves within the arm; the median, ulnar and radial nerves. Each one has both sensory and motor function, i.e., giving the patient sensation as well as innervating the muscles that help move the hand and arm. If a nerve is lacerated, studies have shown that the best outcome is obtained with early repair of the nerve.
This is because it takes many months for a nerve to regenerate from the site of the laceration to its distal end organ or area that it innervates such as a muscle and/or sensory organ. After a nerve is repaired, the nerve regenerates at approximately an inch a month, thus the prognosis is poorer if a nerve laceration is closer to the shoulder than closer to the hand. In addition, children have a better prognosis with regard to repair of nerve lacerations than do adults.
Nerve repairs are done with the use of a microscope and involve very delicate surgery in order to reapproximate and realign the divided nerve fascicles. Postoperatively, the patient is immobilized for several weeks in an effort to protect the nerve repair. If there is a significant gap between the ends of the nerve that precludes direct repair and/or if time is intervened between the ability to repair the nerve in a patient, then nerve grafts and/or neural tubes are often indicated. A nerve graft is typically taken from the patient either from the leg and/or arm in an area that will not render the patient significantly disabled after removal of the nerve.
This nerve is then put in place between the 2 ends of the respective damaged nerve in an effort to serve as a tube and promote the progression and advancement of the nerve regeneration. Neural tubes have been developed and can be used, i.e., artificial tubes to be placed as an interposition between 2cut nerve endings. These are placed when there is only a certain amount of limited distance between the 2 ends of a lacerated nerve, i.e., 2 inches or less. If nerve repairs do not give the patient adequate function, then consideration for tendon transfers can be given.
In these cases, a tendon and its respective muscle which are innervated by non-damaged nerve can be transferred into the area that has been affected by the damaged nerve. Preoperatively, the surgeon determines what muscle are available to transfer that will not cause significant deficit to the patient. Postoperatively, immobilization is performed for approximately 4 weeks to allow the transfers to heal and then a significant amount of postoperative therapy is warranted subsequent to the removal of the immobilization.