Manual of Surgery, Alexis Thomson [new books to read txt] 📗

for repair, and this should be done at the earliest possible opportunity. (Op. Surg., pp. 45, 46.)

Primary Suture.—The reunion of a recently divided nerve is spoken of as primary suture, and for its success asepsis is essential. As the suturing of the ends of the nerve is extremely painful, an anæsthetic is required.

When the wound is healed and while waiting for the restoration of function, measures are employed to maintain the nutrition of the damaged nerve and of the parts supplied by it. The limb is exercised, massaged, and douched, and protected from cold and other injurious influences. The nutrition of the paralysed muscles is further improved by electricity. The galvanic current is employed, using at first a mild current of not more than 5 milliampères for about ten minutes, the current being made to flow downwards in the course of the nerve, with the positive electrode applied to the spine, and the negative over the affected nerve near its termination. It is an advantage to have a metronome in the circuit whereby the current is opened and closed automatically at intervals, so as to cause contraction of the muscles.

The results of primary suture, when it has been performed under favourable conditions, are usually satisfactory. In a series of cases investigated by Head and Sherren, the period between the operation and the first return of sensation averaged 65 days. According to Purves Stewart protopathic sensation commences to appear in about six weeks and is completely restored in six months; electric sensation and motor power reappear together in about six months, and restoration is complete in a year. When sensation returns, the area of insensibility to pain steadily diminishes and disappears; sensibility to extremes of temperature appears soon after; and last of all, after a considerable interval, there is simultaneous return of appreciation of light touch, moderate degrees of temperature, and the points of a compass.

A clinical means of estimating how regeneration in a divided nerve is progressing has been described by Tinel. He found that a tingling sensation, similar to that experienced in the foot, when it is recovering from the “sleeping” condition induced by prolonged pressure on the sciatic nerve from sitting on a hard bench, can be elicited on percussing over growing axis cylinders. Tapping over the proximal end of a newly divided nerve, e.g. the common peroneal behind the head of the fibula, produces no tingling, but when in about three weeks axis cylinders begin to grow in the proximal end-bulb, local tingling is induced by tapping there. The downward growth of the axis cylinders can be traced by tapping over the distal segment of the nerve, the tingling sensation being elicited as far down as the young axis cylinders have reached. When the regeneration of the axis cylinders is complete, tapping no longer causes tingling. It usually takes about one hundred days for this stage to be reached.

Tinel's sign is present before voluntary movement, muscular tone, or the normal electrical reactions reappear.

In cases of complete nerve paralysis that have not been operated upon, the tingling test is helpful in determining whether or not regeneration is taking place. Its detection may prevent an unnecessary operation being performed.

Primary suture should not be attempted so long as the wound shows signs of infection, as it is almost certain to end in failure. The ends should be sutured, however, as soon as the wound is aseptic or has healed.

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.

Dislocation of Nerves.—This injury, which resembles the dislocation of tendons from their grooves, is seldom met with except in the ulnar nerve at the elbow, and is described with injuries of that nerve.

DISEASES OF NERVES

Traumatic Neuritis.—This consists in an overgrowth of the connective-tissue framework of a nerve, which causes irritation and pressure upon the nerve fibres, sometimes resulting in their degeneration. It may originate in connection with a wound in the vicinity of a nerve, as, for example, when the brachial nerves are involved in scar tissue subsequent to an operation for clearing out the axilla for cancer; or in contusion and compression of a nerve—for example, by the pressure of the head of the humerus in a dislocation of the shoulder. Some weeks or months after the injury, the patient complains of increasing hyperæsthesia and of neuralgic pains in the course of the nerve. The nerve is very sensitive to pressure, and, if superficial, may be felt to be swollen. The associated muscles are wasted and weak, and are subject to twitchings. There are also trophic disturbances. It is rare to have complete sensory and motor paralysis. The disease is commonest in the nerves of the upper extremity, and the hand may become crippled and useless.

Treatment.—Any constitutional condition which predisposes to neuritis, such as gout, diabetes, or syphilis, must receive appropriate treatment. The symptoms may be relieved by rest and by soothing applications, such as belladonna, ichthyol, or menthol, by the use of hot-air and electric baths, and in obstinate cases by blistering or by the application of Corrigan's button. When such treatment fails the nerve may be stretched, or, in the case of a purely sensory trunk, a portion may be excised. Local causes, such as involvement of the nerve in a scar or in adhesions, may afford indications for operative treatment.

Multiple Peripheral Neuritis.—Although this disease mainly comes under the cognizance of the physician, it may be attended with phenomena which call for surgical interference. In this country it is commonly due to alcoholism, but it may result from diabetes or from chronic poisoning with lead or arsenic, or from bacterial infections and intoxications such as occur in diphtheria, gonorrhœa, syphilis, leprosy, typhoid, influenza, beri-beri, and many other diseases.

It is, as a rule, widely distributed throughout the peripheral nerves, but the distribution frequently varies with the cause—the alcoholic form, for example, mainly affecting the legs, the diphtheritic form the soft palate and pharynx, and that associated with lead poisoning the forearms. The essential lesion is a degeneration of the conducting fibres of the affected nerves, and the prominent symptoms are the result of this. In alcoholic neuritis there is great tenderness of the muscles. When the legs are affected the patient may be unable to walk, and the toes may droop and the heel be drawn up, resulting in one variety of pes equino-varus. Pressure sores and perforating ulcer of the foot are the most important trophic phenomena.

Apart from the medical treatment, measures must be taken to prevent deformity, especially when the legs are affected. The bedclothes are supported by a cage, and the foot maintained at right angles to the leg by sand-bags or splints. When the disease is subsiding, the nutrition of the damaged nerves and muscles should be maintained by massage, baths, passive movements, and the use of the galvanic current. When deformity has been allowed to take place, operative measures may be required for its correction.

NEUROMA[5]

[5] We have followed the classification adopted by