Manual of Surgery Volume First: General Surgery. Sixth Edition.

by Alexis Thomson; Alexander Miles

The nerve slips forward, and may be felt lying on the medial aspect of the condyle. It may retain this position, or it may slip backwards and forwards with the movements of the arm. The symptoms at the time of the displacement are some disability at the elbow, and pain and tingling along the nerve, which are exaggerated by movement and by pressure. The symptoms may subside altogether, or a neuritis may develop, with severe pain shooting up the nerve.

The dislocated nerve is easily replaced, but is difficult to retain in position. In recent cases the arm may be placed in the extended position with a pad over the condyle, care being taken to avoid pressure on the nerve. Failing relief, it is better to make a bed for the nerve by dividing the deep fascia behind the medial condyle and to stitch the edges of the fascia over the nerve. This operation has been successful in all the recorded cases.

The Sciatic Nerve.—When this nerve is compressed, as by sitting on a fence, there is tingling and powerlessness in the limb as a whole, known as “sleeping” of the limb, but these phenomena are evanescent. Injuries to the great sciatic nerve are rare except in war. Partial division is more common than complete, and it is noteworthy that the fibres destined for the peroneal nerve are more often and more severely injured than those for the tibial (internal popliteal). After complete division, all the muscles of the leg are paralysed; if the section is in the upper part of the thigh, the hamstrings are also paralysed. The limb is at first quite powerless, but the patient usually recovers sufficiently to be able to walk with a little support, and although the hamstrings are paralysed the knee can be flexed by the sartorius and gracilis. The chief feature is drop-foot. There is also loss of sensation below the knee except along the course of the long saphenous nerve on the medial side of the leg and foot. Sensibility to deep touch is only lost over a comparatively small area on the dorsum of the foot.

The Common Peroneal (external popliteal) nerve is exposed to injury where it winds round the neck of the fibula, because it is superficial and lies against the unyielding bone. It may be compressed by a tourniquet, or it may be bruised or torn in fractures of the upper end of the bone. It has been divided in accidental wounds,—by a scythe, for example,—in incising for cellulitis, and in performing subcutaneous tenotomy of the biceps tendon. Cases have been observed of paralysis of the nerve as a result of prolonged acute flexion of the knee in certain occupations.

When the nerve is divided, the most obvious result is “drop-foot”; the patient is unable to dorsiflex the foot and cannot lift his toes off the ground, so that in walking he is obliged to jerk the foot forwards and laterally. The loss of sensibility depends upon whether the nerve is divided above or below the origin of the large cutaneous branch which comes off just before it passes round the neck of the fibula. In course of time the foot becomes inverted and the toes are pointed—pes equino-varus—and trophic sores are liable to form.

The Tibial (internal popliteal) nerve is rarely injured.

The Cranial nerves are considered with affections of the head and neck (Vol. II.).

NEURALGIA

The term neuralgia is applied clinically to any pain which follows the course of a nerve, and is not referable to any discoverable cause. It should not be applied to pain which results from pressure on a nerve by a tumour, a mass of callus, an aneurysm, or by any similar gross lesion. We shall only consider here those forms of neuralgia which are amenable to surgical treatment.

Brachial Neuralgia.—The pain is definitely located in the distribution of one of the branches or nerve roots, is often intermittent, and is usually associated with tingling and disturbance of tactile sensation. The root of the neck should be examined to exclude pressure as the cause of the pain by a cervical rib, a tumour, or an aneurysm. When medical treatment fails, the nerve-trunks may be injected with saline solution or recourse may be had to operative measures, the affected cords being exposed and stretched through an incision in the posterior triangle of the neck. If this fails to give relief, the more serious operation of resecting the posterior roots of the affected nerves within the vertebral canal may be considered.