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

by Alexis Thomson; Alexander Miles

Secondary Suture.—The term secondary suture is applied to the operation of stitching the ends of the divided nerve after the wound has healed.

Results of Secondary Suture.—When secondary suture has been performed under favourable conditions, the prognosis is good, but a longer time is required for restoration of function than after primary suture. Purves Stewart says protopathic sensation is sometimes observed much earlier than in primary suture, because partial regeneration of axis cylinders in the peripheral segment has already taken place. Sensation is recovered first, but it seldom returns before three or four months. There then follows an improvement or disappearance of any trophic disturbances that may be present. Recovery of motion may be deferred for long periods—rather because of the changes in the muscles than from want of conductivity in the nerve—and if the muscles have undergone complete degeneration, it may never take place at all. While waiting for recovery, every effort should be made to maintain the nutrition of the damaged nerve, and of the parts which it supplies.

When suture is found to be impossible, recourse must be had to other methods, known as nerve bridging and nerve implantation.

Incomplete Division of a Mixed Nerve.—The effects of partial division of a mixed nerve vary according to the destination of the nerve bundles that have been interrupted. Within their area of distribution the paralysis is as complete as if the whole trunk had been cut across. The uninjured nerve-bundles continue to transmit impulses with the result that there is a dissociated paralysis within the distribution of the affected nerve, some muscles continuing to act and to respond normally to electric stimulation, while others behave as if the whole nerve-trunk had been severed.

In addition to vasomotor and trophic changes, there is often severe pain of a burning kind (causalgia or thermalgia) which comes on about a fortnight after the injury and causes intense and continuous suffering which may last for months. Paroxysms of pain may be excited by the slightest touch or by heat, and the patient usually learns for himself that the constant application of cold wet cloths allays the pain. The thermalgic area sweats profusely.

Operative treatment is indicated where there is no sign of improvement within three months, when recovery is arrested before complete restoration of function is attained, or when thermalgic pain is excessive.

Subcutaneous Injuries of Nerves.—Several varieties of subcutaneous injuries of nerves are met with. One of the best known is the compression paralysis of the nerves of the upper arm which results from sleeping with the arm resting on the back of a chair or the edge of a table—the so-called “drunkard's palsy”; and from the pressure of a crutch in the axilla—“crutch paralysis.” In some of these injuries, notably “drunkard's palsy,” the disability appears to be due not to damage of the nerve, but to overstretching of the extensors of the wrist and fingers (Jones). A similar form of paralysis is sometimes met with from the pressure of a tourniquet, from tight bandages or splints, from the pressure exerted by a dislocated bone or by excessive callus, and from hyper-extension of the arm during anæsthesia.

In all these forms there is impaired sensation, rarely amounting to anæsthesia, marked muscular wasting, and diminution or loss of voluntary motor power, while—and this is a point of great importance—the normal electrical reactions are preserved. There may also develop trophic changes such as blisters, superficial ulcers, and clubbing of the tips of the fingers. The prognosis is usually favourable, as recovery is the rule within from one to three months. If, however, neuritis supervenes, the electrical reactions are altered, the muscles degenerate, and recovery may be retarded or may fail to take place.

Injuries which act abruptly or instantaneously are illustrated in the crushing of a nerve by the sudden displacement of a sharp-edged fragment of bone, as may occur in comminuted fractures of the humerus. The symptoms include perversion or loss of sensation, motor paralysis, and atrophy of muscles, which show the reaction of degeneration from the eighth day onwards. The presence of the reaction of degeneration influences both the prognosis and the treatment, for it implies a lesion which is probably incapable of spontaneous recovery, and which can only be remedied by operation.

The treatment varies with the cause and nature of the lesion. When, for example, a displaced bone or a mass of callus is pressing upon the nerve, steps must be taken to relieve the pressure, by operation if necessary. When there is reason to believe that the nerve is severely crushed or torn across, it should be exposed by incision, and, after removal of the damaged ends, should be united by sutures. When it is impossible to make a definite diagnosis as to the state of the nerve, it is better to expose it by operation, and thus learn the exact state of affairs without delay; in the event of the nerve being torn, the ends should be united by sutures.