<P> Surgery can be done in case a peripheral nerve has become cut or otherwise divided . This is called peripheral nerve reconstruction . The injured nerve is identified and exposed so that normal nerve tissue can be examined above and below the level of injury, usually with magnification, using either loupes or an operating microscope . If a large segment of nerve is harmed, as can happen in a crush or stretch injury, the nerve will need to be exposed over a larger area . Injured portions of the nerve are removed . The cut nerve endings are then carefully reapproximated using very small sutures . The nerve repair must be covered by healthy tissue, which can be as simple as closing the skin or it can require moving skin or muscle to provide healthy padded coverage over the nerve . The type of anesthesia used depends on the complexity of the injury . A surgical tourniquet is almost always used . </P> <P> The expectations after surgical repair of a divided peripheral nerve depends on several factors: </P> <Ul> <Li> Age: Recovery of a nerve after surgical repair depends mainly on the age of the patient . Young children can recover close - to - normal nerve function . In contrast, a patient over 60 years old with a cut nerve in the hand would expect to recover only protective sensation; that is, the ability to distinguish hot / cold or sharp / dull . </Li> <Li> The mechanism of injury: Sharp injuries, such as a knife wound, damage only a very short segment of the nerve, availing for direct suture . In contrast, nerves that are divided by stretch or crush may be damaged over long segments . These nerve injuries are more difficult to treat and generally have a poorer outcome . In addition, associated injuries, like injury to bone, muscle and skin, can make nerve recovery more difficult . </Li> <Li> The level of injury: After a nerve is repaired, the regenerating nerve endings must grow all the way to their target . For example, a nerve injured at the wrist that normally provides sensation to the thumb must grow to the end of the thumb in order to provide sensation . The return of function decreases with increased distance over which a nerve must grow . </Li> </Ul> <Li> Age: Recovery of a nerve after surgical repair depends mainly on the age of the patient . Young children can recover close - to - normal nerve function . In contrast, a patient over 60 years old with a cut nerve in the hand would expect to recover only protective sensation; that is, the ability to distinguish hot / cold or sharp / dull . </Li>

Why is an intact endoneurium beneficial in nerve regeneration