PRIMARY MYOSITIS - DISEASES OF THE MUSCLES.
We may say that the work of Pasteur and of his followers has thrown new light upon the entire field of medicine; and the chapter on myositis forms no exception to this statement. Indeed, the ques tions of its etiology and pathology have profited much from the light given forth by these remarkable discoveries. Up to that time we were only able to note the existence of an inflammatory condition in volving a particular muscle or group of muscles, going on sometimes to suppuration, but we were unable to explain the reason for this par ticular localization independent of any general disease. Among the determining causes were mentioned cold and fatigue, but in that we had only one element of the problem. When, however, it was demon strated that, in addition to these causes acting as depressants upon the organism, there was necessary a penetration of germs coming from without, or already present in the tissues and assuming a special virulence in consequence of the lessened resisting powers of the parts, then the second pathological element was found and an end was put to all the various hypotheses formerly in vogue. Some had described myositis as an inflammation of rheumatic nature; others, among whom was Grisolle, contented themselves with noting the fact of the inflammation, calling attention particularly to its infrequence. Fi nally, under the influence of the theories put forth by Tessier, myo sitis was grouped among the affections due to the purulent diathesis, and Dufresne (Paris, 1888) undertook to champion this opinion. Brunon, in his inaugural thesis (Paris, 1887) and in two subsequent publications (1890-91), elevated primary myositis to the dignity of a distinct morbid entity, and we may say that he has put the matter absolutely in its proper light. We may also mention the works of Striimpell, Hayem, Gluzinski, Larger, and many others.
Etiology.—Primary myositis is a comparatively rare affection. On this point all authors are agreed. It occurs generally in young persons. Among the alleged etiological factors two seem to be of real importance, viz., cold and fatigue. If we ask a patient suffering
from acute myositis, whatever its intensity or location, how it was acquired, we shall usually learn that a short time before the disease made its appearance he was engaged in some very laborious under taking, or endured some excessive fatigue--in a word, that he was overworked. Often also it will be learned that he experienced a sud den chill while perspiring, or that he was caught in a soaking rain. Such being among the active exciting causes, we ought not to be su• prised at the greater frequency of primary myositis among soldiers than among those in civil life. It is among recruits especially, who have not yet become accustomed to violent exercises, that myositis is most frequently observed. Constant rubbing, pressure, or contusions of a muscular region may also play an important part in the production of the disease which we are now considering. Next in order come mental disturbances and other influences which tend to depress the general condition, and finally may be mentioned malnutrition in con sequence of insufficient quality or quantity of food. In a word any cause which weakens the resisting powers, and especially anything which also affects chiefly the muscular tissue, may act as an excitant of myositis. It is always the working muscles that are attacked.
But in addition to a suitable soil we must have the cultivation of the germ. It is very evident that in a field so well prepared by all the external factors which we have just mentioned, the micro-organ ism will find a soil very favorable to its development and growth. And this is, indeed, what occurs. Brunon succeeded in obtaining from the muscles of a person (lead from primary myositis a certain number of microbes among which he found the streptococcus. The predominating role of micro-organisms in the pathogenesis of the in flammation is undeniable, and moreover it is often possible to prove that the person affected has been exposed for a longer or shorter pe riod in a locality infected by the microbes of suppuration.