OPERATIVE APPROACHES TO THE NERVES
@@@Various kinds of anaesthesia are applied in operations on the peripheral nerves: general, local and lumbar. Concerning the choice of anaesthesia there is no unified opinion. The long duration of the operation on the peripheral nerves is a reason to prefer general anaesthesia in the majority of cases. Because a nerve graft is necessary in some cases, this provides another argument in favour of the frequent use of general anaesthesia. Muscle relaxants disturb diagnostic nerve stimulation and should be avoided. In a large number of operations on peripheral nerves, local anaesthesia with general sedation can be used.
The patient's position on the operative table differs according to the different nerve trunks that are being approached and the level of the lesion. One of the two legs is prepared as an operative field to be ready if it is necessary to take a sural nerve as a graft. The limbs should be free for observation of the results of intraoperative electrodiagnostic tests and to evaluate the different muscles and tendons.
The operative exposure of the peripheral nerves should aim not only to reach them very quickly and easily but also to establish their sufficiently broad exposure so that all anatomic details related to the injury be established. Skin incisions are usually made along the limbs. In open injuries of the nerves, when there is a skin scar, it is excised if this is possible, at least in those parts, toward the deep tissues and where there is no subcutaneous fatty tissue. With transverse disposition of the skin scars, two curved incisions are sufficient as a continuation superior and inferior to the skin scar so that a common incision is formed in the shape of letter S. It is very important to comply with the rules - to have the incisions of the skin, subcutaneous tissue and fascia made a little away, i.e. outside the projection of the nerves, so that the scar acquired from the suturing be far away from the nerve trunks. The incisions outside the nerve projection are suitable in operations of the medial surface of the arm, in the lower third of the forearm, and around the capitulum fibulae. In some other regions, where the nerves are situated among powerful muscles, as for instance the sciatic nerve in the superior and middle third of the thigh, the incisions outside the nerve projection have no advantage over the approaches along it. It is important also to do the skin incisions along the skin creases in the flexion surface of the elbow and the knee. The incisions crossing the skin creases perpendicularly frequently leave a badly disposed scar, which stretches when the respective joint is extended. Incisions applied in the approaches to the nerves in the neck and infra-clavicular region should coincide with skin creases. They leave better scars than do incisions along the nerve projections.
In reaching the nerve trunks under the fascia, it should be penetrated carefully between the muscles and the muscle groups. No incision of muscles near or above the nerve trunks should be performed. If cutting of muscles is necessary, this is done outside the projection of the nerve near their insertion (Fig. 20-4).
The operative wounds should be broad and convenient for work, so that the surgeon may carry out all manipulations around the nerve trunk. The skin scar, if it is found above the injured nerve, is cleaned from the surrounding muscles. The scar in the depth of the wound is left temporarily and the nerve trunk is revealed within normal tissues, above and below the place of injury. After the separation the nerve trunks above and below the place of the lesion, and as necessary, various interventions are made upon them, such as neurolysis (external and internal), resection of a neuroma, nerve sutures, etc.