Manual of Surgery Volume I Part 40

It is important to remember that when the median nerve is divided at the wrist, deep touch can be appreciated over the whole of the area supplied by the nerve; the injury, therefore, is liable to be over looked. If, however, the tendons are divided as well as the nerve, there is insensibility to deep touch. The areas of epicritic and of protopathic insensibility are ill.u.s.trated in Fig. 91. The division of the nerve at the elbow, or even at the axilla, does not increase the extent of the loss of epicritic or protopathic sensibility, but usually affects deep sensibility.

[Ill.u.s.tration: FIG. 92.--To ill.u.s.trate Loss of Sensation produced by complete Division of Ulnar Nerve. Loss of all forms of cutaneous sensibility is represented by the shaded area. The parts insensitive to light touch and to intermediate degrees of heat and cold are enclosed within the dotted line.

(Head and Sherren.)]

#The Ulnar Nerve.#--The most common injury of this nerve is its division in transverse accidental wounds just above the wrist. In the arm it may be contused, along with the radial, in crutch paralysis; in the region of the elbow it may be injured in fractures or dislocations, or it may be accidentally divided in the operation for excising the elbow-joint.

When it is injured _at or above the elbow_, there is paralysis of the flexor carpi ulnaris, the ulnar half of the flexor digitorum profundus, all the interossei, the two medial lumbricals, and the adductors of the thumb. The hand a.s.sumes a characteristic att.i.tude: the index and middle fingers are extended at the metacarpo-phalangeal joints owing to paralysis of the interosseous muscles attached to them; the little and ring fingers are hyper-extended at these joints in consequence of the paralysis of the lumbricals; all the fingers are flexed at the inter-phalangeal joints, the flexion being most marked in the little and ring fingers--claw-hand or _main en griffe_. On flexing the wrist, the hand is tilted to the radial side, but the paralysis of the flexor carpi ulnaris is often compensated for by the action of the palmaris longus.

The little and ring fingers can be flexed to a slight degree by the slips of the flexor sublimis attached to them and supplied by the median nerve; flexion of the terminal phalanx of the little finger is almost impossible. Adduction and abduction movements of the fingers are lost.

Adduction of the thumb is carried out, not by the paralysed adductor pollicis, but the movement may be simulated by the long flexor and extensor muscles of the thumb. Epicritic sensibility is lost over the little finger, the ulnar half of the ring finger, and that part of the palm and dorsum of the hand to the ulnar side of a line drawn longitudinally through the ring finger and continued upwards.

Protopathic sensibility is lost over an area which varies in different cases. Deep sensibility is usually lost over an area almost as extensive as that of protopathic insensibility.

When the nerve is _divided at the wrist_, the adjacent tendons are also frequently severed. If divided below the point at which its dorsal branch is given off, the sensory paralysis is much less marked, and the injury is therefore liable to be overlooked until the wasting of muscles and typical _main en griffe_ ensue. The loss of sensibility after division of the nerve before the dorsal branch is given off resembles that after division at the elbow, except that in uncomplicated cases deep sensibility is usually retained. If the tendons are divided as well, however, deep touch is also lost.

Care must be taken in all these injuries to prevent deformity; a splint must be worn, at least during the night, until the muscles regain their power of voluntary movement, and then exercises should be inst.i.tuted.

#Dislocation of the ulnar nerve# at the elbow results from sudden and violent flexion of the joint, the muscular effort causing stretching or laceration of the fascia that holds the nerve in its groove; it is predisposed to if the groove is shallow as a result of imperfect development of the medial condyle of the humerus, and by cubitus valgus.

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 st.i.tch 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 pa.s.ses 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 ma.s.s 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 a.s.sociated 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 ca.n.a.l may be considered.

_Neuralgia of the sciatic nerve_--#sciatica#--is the most common form of neuralgia met with in surgical practice.

It is chiefly met with in adults of gouty or rheumatic tendencies who suffer from indigestion, constipation, and oxaluria--in fact, the same type of patients who are liable to lumbago, and the two affections are frequently a.s.sociated. In hospital practice it is commonly met with in coal-miners and others who a.s.sume a squatting position at work. The onset of the pain may follow over-exertion and exposure to cold and wet, especially in those who do not take regular exercise. Any error of diet or indulgence in beer or wine may contribute to its development.

The essential symptom is paroxysmal or continuous pain along the course of the nerve in the b.u.t.tock, thigh, or leg. It may be comparatively slight, or it may be so severe as to prevent sleep. It is aggravated by movement, so that the patient walks lame or is obliged to lie up. It is aggravated also by any movement which tends to put the nerve on the stretch, as in bending down to put on the shoes, such movements also causing tingling down the nerve, and sometimes numbness in the foot.

This may be demonstrated by flexing the thigh on the abdomen, the knee being kept extended; there is no pain if the same manuvre is repeated with the knee flexed. The nerve is sensitive to pressure, the most tender points being its emergence from the greater sciatic foramen, the hollow between the trochanter and the ischial tuberosity, and where the common peroneal nerve winds round the neck of the fibula. The muscles of the thigh are often wasted and are liable to twitch.

The clinical features vary a good deal in different cases; the affection is often obstinate, and may last for many weeks or even months.

In the sciatica that results from neuritis and perineuritis, there is marked tenderness on pressure due to the involvement of the nerve filaments in the sheath of the nerve, and there may be patches of cutaneous anaesthesia, loss of tendon reflexes, localised wasting of muscles, and vaso-motor and trophic changes. The presence of the reaction of degeneration confirms the diagnosis of neuritis. In long-standing cases the pain and discomfort may lead to a postural scoliosis (_ischias-scoliotica_).

_Diagnosis._--Pain referred along the course of the sciatic nerve on one side, or, as is sometimes the case, on both sides, is a symptom of tumours of the uterus, the r.e.c.t.u.m, or the pelvic bones. It may result also from the pressure of an abscess or an aneurysm either inside the pelvis or in the b.u.t.tock, and is sometimes a.s.sociated with disease of the spinal medulla, such as tabes. Gluteal fibrositis may be mistaken for sciatica. It is also necessary to exclude such conditions as disease in the hip or sacro-iliac joint, especially tuberculous disease and arthritis deformans, before arriving at a diagnosis of sciatica. A digital examination of the r.e.c.t.u.m or v.a.g.i.n.a is of great value in excluding intra-pelvic tumours.

_Treatment_ is both general and local. Any const.i.tutional tendency, such as gout or rheumatism, must be counteracted, and indigestion, oxaluria, and constipation should receive appropriate treatment. In acute cases the patient is confined to bed between blankets, the limb is wrapped in thermogene wool, and the knee is flexed over a pillow; in some cases relief is experienced from the use of a long splint, or slinging the leg in a Salter's cradle. A rubber hot-bottle may be applied over the seat of greatest pain. The bowels should be well opened by castor oil or by calomel followed by a saline. Salicylate of soda in full doses, or aspirin, usually proves effectual in relieving pain, but when this is very intense it may call for injections of heroin or morphin. Pota.s.sium iodide is of benefit in chronic cases.

Relief usually results from bathing, douching, and ma.s.sage, and from repeated gentle stretching of the nerve. This may be carried out by pa.s.sive movements of the limb--the hip being flexed while the knee is kept extended; and by active movements--the patient flexing the limb at the hip, the knee being maintained in the extended position. These exercises, which may be preceded by ma.s.sage, are carried out night and morning, and should be practised systematically by those who are liable to sciatica.

Benefit has followed the injection into the nerve itself, or into the tissues surrounding it, of normal saline solution; from 70100 c.c. are injected at one time. If the pain recurs, the injection may require to be repeated on many occasions at different points up and down the nerve.

Needling or acupuncture consists in piercing the nerve at intervals in the b.u.t.tock and thigh with long steel needles. Six or eight needles are inserted and left in position for from fifteen to thirty minutes.

In obstinate and severe cases the nerve may be _forcibly stretched_.

This may be done bloodlessly by placing the patient on his back with the hip flexed to a right angle, and then gradually extending the knee until it is in a straight line with the thigh (Billroth). A general anaesthetic is usually required. A more effectual method is to expose the nerve through an incision at the fold of the b.u.t.tock, and forcibly pull upon it. This operation is most successful when the pain is due to the nerve being involved in adhesions.

#Trigeminal Neuralgia.#--A severe form of epileptiform neuralgia occurs in the branches of the fifth nerve, and is one of the most painful affections to which human flesh is liable. So far as its pathology is known, it is believed to be due to degenerative changes in the semilunar (Ga.s.serian) ganglion. It is met with in adults, is almost invariably unilateral, and develops without apparent cause. The pain, which occurs in paroxysms, is at first of moderate severity, but gradually becomes agonising. In the early stages the paroxysms occur at wide intervals, but later they recur with such frequency as to be almost continuous.

They are usually excited by some trivial cause, such as moving the jaws in eating or speaking, touching the face as in washing, or exposure to a draught of cold air. Between the paroxysms the patient is free from pain, but is in constant terror of its return, and the face wears an expression of extreme suffering and anxiety. When the paroxysm is accompanied by twitching of the facial muscles, it is called _spasmodic tic_.

The skin of the affected area may be glazed and red, or may be pale and moist with insp.i.s.sated sweat, the patient not daring to touch or wash it.

There is excessive tenderness at the points of emergence of the different branches on the face, and pressure over one or other of these points may excite a paroxysm. In typical cases the patient is unable to take any active part in life. The attempt to eat is attended with such severe pain that he avoids taking food. In some cases the suffering is so great that the patient only obtains sleep by the use of hypnotics, and he is often on the verge of suicide.

_Diagnosis._--There is seldom any difficulty in recognising the disease.

It is important, however, to exclude the hysterical form of neuralgia, which is characterised by its occurrence earlier in life, by the pain varying in situation, being frequently bilateral, and being more often constant than paroxysmal.

_Treatment._--Before having recourse to the measures described below, it is advisable to give a thorough trial to the medical measures used in the treatment of neuralgia.

_The Injection of Alcohol into the Nerve._--The alcohol acts by destroying the nerve fibres, and must be brought into direct contact with them; if the nerve has been properly struck the injection is followed by complete anaesthesia in the distribution of the nerve. The relief may last for from six months to three years; if the pain returns, the injection may be repeated. The strength of the alcohol should be 85 per cent., and the amount injected about 2 c.c.; a general, or preferably a local, anaesthetic (novocain) should be employed (Schlosser); the needle is 8 cm. long, and 0.7 mm. in diameter. The severe pain which the alcohol causes may be lessened, after the needle has penetrated to the necessary depth, by pa.s.sing a few cubic centimetres of a 2 per cent. solution of _novocain-suprarenin_ through it before the alcohol is injected. The treatment by injection of alcohol is superior to the resection of branches of the nerve, for though relapses occur after the treatment with alcohol, renewed freedom from pain may be obtained by its repet.i.tion. The ophthalmic division should not, however, be treated in this manner, for the alcohol may escape into the orbit and endanger other nerves in this region. Harris recommends the injection of alcohol into the semilunar ganglion.

_Operative Treatment._--This consists in the removal of the affected nerve or nerves, either by resection--_neurectomy_; or by a combination of resection with twisting or tearing of the nerve from its central connections--_avulsion_. To prevent the regeneration of the nerve after these operations, the ca.n.a.l of exit through the bone should be obliterated; this is best accomplished by a silver screw-nail driven home by an ordinary screw-driver (Charles H. Mayo).

When the neuralgia involves branches of two or of all three trunks, or when it has recurred after temporary relief following resection of individual branches, the _removal of the semilunar ganglion_, along with the main trunks of the maxillary and mandibular divisions, should be considered.

The operation is a difficult and serious one, but the results are satisfactory so far as the cure of the neuralgia is concerned. There is little or no disability from the unilateral paralysis of the muscles of mastication; but on account of the insensitiveness of the cornea, the eye must be protected from irritation, especially during the first month or two after the operation; this may be done by fixing a large watch-gla.s.s around the edge of the orbit with adhesive plaster.

If the ophthalmic branch is not involved, neither it nor the ganglion should be interfered with; the maxillary and mandibular divisions should be divided within the skull, and the foramen rotundum and foramen ovale obliterated.

CHAPTER XVII

THE SKIN AND SUBCUTANEOUS TISSUE

Structure of skin--_Blisters_--_Callosities_--_Corns_--_Chilblains_ --_Boils_--_Carbuncle_--_Abscess_--_Veldt sores_--Tuberculosis of skin: _Inoculation tubercle_--_Lupus_: _Varieties_--Sporotrichosis --Elephantiasis--Sebaceous cysts or wens--Moles--Horns--New growths: _Fibroma_; _Papilloma_; _Adenoma_; _Epithelioma_; _Rodent cancer_; _Melanotic cancer_; _Sarcoma_--AFFECTIONS OF CICATRICES--_Varieties of scars_--_Keloid_--_Tumours_--AFFECTIONS OF NAILS.

#Structure of Skin.#--The skin is composed of a superficial cellular layer--the epidermis, and the corium or true skin. The _epidermis_ is differentiated from without inwards into the stratum corneum, the stratum lucidum, the stratum granulosum, and the rete Malpighii or germinal layer, from which all the others are developed. The _corium_ or _true skin_ consists of connective tissue, in which ramify the blood vessels, lymphatics, and nerves. That part of the corium immediately adjoining the epidermis is known as the papillary portion, and contains the terminal loops of the cutaneous blood vessels and the terminations of the cutaneous nerves. The deeper portion of the true skin is known as the reticular portion, and is largely composed of adipose tissue.

#Blisters# result from the exudation of serous fluid beneath the h.o.r.n.y layer of the epidermis. The fluid may be clear, as in the blisters of a recent burn, or blood-stained, as in the blisters commonly accompanying fractures of the leg. It may become purulent as a result of infection, and this may be the starting-point of lymphangitis or cellulitis.