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Recovery from the consequences of the inflammation is not always complete. The limb often remains smaller and feebler, with a liability to tingling and to cramp, and also to neuralgic pains under the influence of changes in the weather, &c. But the most serious consequences are the alterations in the joints. These are very frequent: the fixation occasioned by the pain permits, and the tendency to perverted nutrition produces, adhesion between the articular surfaces, in consequence of which the movement becomes permanently restrained. It is probable, moreover, that the constitutional state which underlies the primary malady often increases the degree of these joint-alterations. The shoulder, wrist, and fingers are the joints that are most frequently thus rendered stiff. The interference with the movement of the fingers is especially troublesome; the joints become painful in consequence of the unavoidable strain on the tissues when an attempt at use is made.

TREATMENT. The treatment that has been described, as needed in neuritis generally, is suitable also for this form, and its details need not here be repeated. Abstinence from movement is of great importance; the occurrence of stiffness of the joints in consequence of the immobility of the limb must be risked. It is doubtful, indeed, whether the tendency to this is much increased thereby, for the effect of pain, in preventing sufficient movement to maintain the normal state of the joints, is not materially increased by rest otherwise enforced; while the difference between a little movement and none, during the acute stage of the affection, is enough to make a considerable difference in the effect on the inflammation of the nerves. The influence of cocaine, injected under the skin, is very beneficial, but it is needed frequently in severe cases, and two injections (each gr.) may be given daily during the height of the disease. It is important that the nerves should not be irritated by massage in the state of active inflammation; indeed, no therapeutic measure which occasions pain can do as much good as harm. After the tenderness has subsided, gentle rubbing, such as is agreeable, may be employed with advantage. Electricity is only needed for muscles that present the reaction of degeneration, or to aid in removing after-pains.

SCIATICA.

As the word sciatica is commonly used, it is a general designation for all affections of which the chief symptom is pain in the region of the sciatic nerve. It is thus often applied to the pain which results from pressure on the nerve in the pelvis, as by a tumour. In a stricter use of the word, however, it is applied to painful affections of the nerve not due to any cause outside it. The two varieties may be distinguished

as secondary and primary sciatica. Primary sciatica is commonly regarded as a neuralgia. This view is in the main erroneous; the vast majority of cases of sciatica are really cases of neuritis of the sciatic nerve. The reasons for this opinion are given in the section on the pathology of the disease.

CAUSES. Sciatica is far more frequent in males than in females; the proportion has been very variously estimated. It is difficult to obtain statistics on the malady that are free from sources of fallacy, since comparatively few cases enter general hospitals. The incidence of severe sciatica seeurs to be fairly presented by the 137 cases that were treated in the Devonshire Hospital, Buxton, during the year 1883, and there is no reason to suppose that slight cases differ, in this respect, from those that are severe. The percentage of males is 82; of females, 18; giving a ratio of 4 to 1, which is probably very near the truth-a remarkable contrast to the analogous affection of the The disease is unknown in childhood, and rare in the second decade of life. It is most frequent between forty and fifty, next between fifty and sixty, and next between thirty and forty. The percentage distribution of the 137 cases at Buxton is as follows:-Ten to twenty, 3 per cent.; twenty to thirty, 9 per cent.; thirty to forty, 19 per cent.; forty to fifty, 29 per cent.; fifty to sixty, 25 per cent.; sixty to seventy, 13 per cent.; over seventy, 1 per cent. The influence of age is nearly the same in each sex.

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Two constitutional conditions are potent factors in the production of sciatica-gout, and that form of rheumatism which affects chiefly the fibrous tissues of the muscles. These two constitutional states cannot be entirely separated, but many of the sufferers are of opposite types: some are stout, plethoric, distinctly gouty; others pale, weakly, and rheumatic. Many of the latter owe their rheumatism to inherited gout; rheumatic fever is certainly one of the effects of this family tendency. Sciatica is most common among those who are gouty but do not suffer from articular gout, and such individuals often have many attacks. Gouty inheritance is generally to be traced in those. who suffer early from the disease. Syphilis has been supposed in some cases to be the cause of a sciatic neuritis, but the cases are so rare as to make strong and clear evidence desirable.

An exciting cause is to be traced in many of the cases. Exposure to cold is the most common. It is usually local exposure, as by wet boots, standing in water, &c.; sometimes, however, a general chill of the body determines an attack. The exposure to cold may be even more direct, as by sitting on wet grass. I believe that draughty water-closet seats are answerable for some cases. The neuritis often arises by the extension of an adjacent rheumatic affection of the fibrous tissue, especially of that form of lumbago which involves the fibrous attachments of the muscles at the back of the sacrum. This passes down, extending along the fascia, to the nerve-sheath in the neighbourhood of the sciatic notch. (The fact is of much interest,

because it shows that this form of rheumatism must be regarded as inflammatory since it can spread as inflammation.) A few days after the pain reaches the nerve-sheath there may be all the signs of intense inflammation. Mechanical causes also sometimes excite the disease, and still more often co-operate with other influences. The pressure of the edge of the chair, in those who sit much, is the most frequent mechanical cause. Muscular over-exertion has been thought occasionally to excite the disease. If the nerve is already tender, a strong contraction of the muscles at the back of the thigh, especially when the knee is flexed, and the muscles can freely shorten and widen, may produce acute pain in the nerve, evidently by its compression. It is conceivable, therefore, that this cause may be effective in a predisposed person. Various morbid processes within the pelvis may cause symptoms of sciatica, usually by acting on the sacral plexus. Thus rectal and other tumours, pelvic inflammation, and injury during labour are occasional causes. A loaded rectum has been thought to be capable of producing sciatica. Mechanical congestion of the plexus of veins which lies over the sacral plexus of nerves is usually regarded as an occasional cause, but this is somewhat hypothetical, and its efficiency can scarcely be demonstrated. Lastly, the sciatic nerve may be secondarily involved in mischief that is outside the pelvis. The most frequent cause of this is disease of the bone, and especially disease of the hip-joint. In all these forms of secondary sciatica the symptoms are due partly to pressure on the nerve, partly to inflammation excited in it by the pressure, or extending to it from the adjacent disease.

PATHOLOGICAL ANATOMY.-Sciatica being a disease that does not itself cause death, observations of the morbid changes are few. In most cases that have been examined, distinct evidence of neuritis has been found, chiefly involving the nerve-sheath, but extending in some cases to the interstitial tissue. The changes are those that have been already described in the account of neuritis (p. 54). In recent cases there is swelling and redness of the sheath, sometimes there are small hæmorrhages, and, in severe cases, similar but slighter alterations in the instertitial tissue, with secondary damage to the nerve-fibres. The signs of inflammation are most intense at the sciatic notch, and opposite the middle of the thigh. They may be limited to one or both of these places, or they may be greatest there, and extend, in slighter degree, over a considerable tract of the nerve.

SYMPTOMS.-The chief symptom of sciatica is pain along the course of the nerve-trunk, often also along that of its branches, and sometimes in the area of its distribution. The affection may begin suddenly, especially in cases of rheumatic origin,-as suddenly as lumbago— generally about the hip or sacrum. Some sudden movement seems to excite it, but there has usually been slighter rheumatic pain in the neighbourhood for a day or two. More frequently the onset is gradual; slight pain is felt along the back of the thigh, on move

ments and in postures that make the nerve tense, or cause pressure upon it. As the disease increases, the pain is more readily produced, and becomes greater in degree, until at last the patient is free from induced pain only when at rest and the leg is in a certain position. Any movement that makes the nerve tense causes extreme suffering, and to avoid this the knee, in walking, is kept slightly flexed, and the leg held stiffly so as to avoid painful changes in the tension of the nerve. As the pain on movement increases, spontaneous pain is added, at first chiefly felt in the nerve-trunk, but soon spreading to its branches and distribution. It is usually most intense in certain spots (1) above the hip-joint, near the posterior iliac spine, (2) at the sciatic notch, (3) about the middle of the thigh, (4) behind the knee, (5) below the head of the fibula, (6) behind the external malleolus, (7) on the back of the foot. The pain may radiate over the whole distribution of the nerve, but it is often so distinctly limited to the course of the trunk and branches, that the patient points these out with exactness when he indicates the course of the pain. It may be dull or acute, is often burning in character, and worse at night. It may seem to dart downwards, starting from the highest point. As the pain on movement increases, the nerve-trunk becomes extremely tender to pressure, especially along the back of the thigh. Even before the tenderness becomes considerable it may often be elicited in the following manner. Let the patient sit on a chair with the knee at a little more than a right angle. If the finger is then pressed into the popliteal space, so as to make the nerve a little more tense, a pain is felt in the course of the nerve at the back of the thigh or above the sciatic notch. It is due to the sensitiveness of the nerve to tension, and is a very useful test. It is of much diagnostic value, especially when the part inflamed is high up within the pelvis, and there is no tenderness to pressure at the back of the thigh.

Abnormal sensations other than pain are often felt in the area of distribution of the nerve,-tingling, formication, and the like; and in severe cases there may be irregular spots of anesthesia on the back of the thigh, on the leg, or the foot. The affection of sensibility at the back of the thigh indicates that the disease extends up the nerve, above the sciatic notch, to the origin of the small sciatic, or that this is involved in a simultaneous neuritis. In severe cases the muscles supplied by the nerve become flabby, tender to the touch, and sometimes distinctly weak and wasted. This is chiefly noticeable in the calf muscles. There may be slight alteration in the electrical irritability, but this amounts to a distinct degenerative reaction only in very severe cases. Slight fever and corresponding constitutional symptoms may attend an onset that is acute, or an inflammation that is intense. Chronic cases, however, are usually not attended by elevation of temperature.

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The duration and severity of the affection are extremely variable. may be trifling in degree, causing pain on movement only, and this

may pass away in the course of a few weeks. On the other hand, the spontaneous pain may be so continuous and intense that sleep can be obtained only by the help of narcotics, and the disease may last for many months, and even for a year. In most cases that last more than a year there is really a relapse of the affection. Improvement is shown by the subsidence of spontaneous pain, followed by the slow diminution of the pain on movement, and of the tenderness of the nerve. The muscular wasting, which occurs in severe cases, may last long after the active stage of the disease in the nerve; and fibrillary contractions in the muscles that have been affected may continue for years, and are sometimes accompanied by a tendency to painful cramp. For a long time after the attack is over, pain is felt in the nerve in certain postures. Occasionally a secondary neuralgia is set up, extending outside the sciatic area. The disease is prone to relapse, and still more prone to recur after recovery. A second attack may occur in the same or in the other leg, but both legs are scarcely ever affected at the same time. I have only once known a true primary sciatic neuritis to be bilateral.

The cases of secondary sciatica depending on disease outside the nerve, compressing or irritating it, differ, in some respects, from the primary form. Pain is felt less in the nerve-trunk than in its distribution. The difference is not absolute; it is one of degree. There is rarely, however, the tenderness of the nerve that is so common in primary sciatica. The course of the secondary cases is also different, and depends on the course of the original disease.

Complications of sciatica are rare, but one or two deserve mention. Cutaneous eruptions, usually herpetic in character, have been occasionally met with. These may heal slowly, but, in themselves, they are unimportant. Sometimes the epidermis exfoliates; edema of the limb occurs in rare cases. A graver complication, but happily a rare one, is a tendency of the mischief to ascend the nerve. Thus symptoms may spread from the region of the sciatic to that of the lumbar plexus; the pain may spread to the front of the thigh, and the extensors of the knee may become flabby and weak. This is probably due to the passage of an ascending neuritis up the lumbo-sacral cord. In extremely rare cases the morbid process has apparently reached the spinal cord, and indications of cord disease have thus succeeded those of a primary and apparently simple sciatica.

PATHOLOGY.-The nature of the disease has been already indicated. The evidence that the disease is a neuritis, and not a neuralgia, is chiefly threefold. The conditions under which the disease occurs are very different from those that attend unquestionable neuralgia in other situations. This has been remarked with surprise, even by those who regard it as a neuralgia, but who have failed to see the significance of the difference. Secondly, the neuritic nature of the affection is clearly indicated by the facts of pathological anatomy, scanty though these are. Thirdly, the symptoms in severe cases are proof of the

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