55.9 Primary nerve repair

A patient’s digital nerves, and his median and ulnar nerves commonly need repairing, but you may occasionally need to repair almost any nerve. Whenever you toilet a wound, inspect any nerves that might be injured, but don’t try to repair them, unless they have been cut completely. Closed injuries usually only bruise nerves, so that they are able to recover in a few weeks.

One of your first problems will be to distinguish a nerve from a tendon deep in a wound. Even supposedly expert surgeons have sutured a nerve to a tendon, especially at the wrist.

A nerve is yellowish and flexible. You can make it lie in various positions, and if you press it, it will flatten fairly easily from side to side and from back to front. Its cut edge bulges slightly. Look at it carefully, if possible with a lens, and you will see its fibres lying in bundles, like fine macaroni. If it has been cut, you can easily see these bundles surrounded by connective tissue. A nerve often has a small tortuous vessel running along its surface. This is a rare on a tendon.

A tendon is bluish white and glistening, straighter and firmer and more difficult to deform by compression than a nerve. It has a flat smooth cut surface like wood cut across the grain, and its bundles are more difficult to see.

Nerve injuries are best referred immediately to an expert. But, if there is no expert, make as good a primary repair as you possibly can yourself, and don’t merely tack the cut ends of the patient’s nerve together with black silk, which is now quite outmoded. If a patient needs a secondary repair later, he will then be in a good position for it. In practice, an attempt at primary repair is likely to be more satisfactory than merely doing an approximate repair in the hope of being able to refer him later.

If, for any reason accurate primary repair has not been possible, the patient’s wound should be re-explored and a secondary repair done between 3 weeks and 3 months later. At 3 weeks fibrosis will no longer be proceeding proximally up his injured nerve and its sheath will be thicker, and better able to hold stitches. If secondary repair is necessary, make this quite clear to the patient and to his relatives, and record it in his notes. Mark the nerve ends with a non–absorbable suture.