The micro-organisms transported by the blood take up their growth in the tissues which happen to offer them the least resistance, in the muscular tissues in the cases now under discussion, and especially in exhausted muscles.
I believe that primary myositis is not dependent for its produc tion upon any single variety of microbe, but that on the contrary every pyogeuic micro-organism or any that is capable of so becom ing, may be arrested in the muscular tissue and excite there troubles analogous to osteomyelitis in osseous tissue. Among these micro organisms I may mention the streptococci, which have been found in the diseased muscles by Brunon, the staphylococci, and the "Aleu t n °cocci .
Patholoyical Arlatomy.—The muscle may present different appear ances according to the degree of the inflammation and also to the length of time that this inflammation has existed. This is what has led various authors, and Harem in particular, to describe several varieties of the affection based upon differences in the anatomical changes. The latter describes the hyperplastic, the calcareous, and the purulent forms of inyositis.
When we examine a part affected by myositis we may often be struck by the lesions of the superficial structures. The skin and cellular tissue may also be involved in the inflammatory process; and on making our incision layer by layer clown to the diseased muscle, we frequently note (edema and inflammatory infiltration with abnor mal vascularity of these parts.
The muscle itself presents different appearances according as it is or is not the seat of a purulent collection. We will consider first the cases in which no suppuration is present. The muscle is seen to be no longer of the bright red color characteristic of healthy flesh; its tint is darker, approaching more nearly to black, yellow, or gray. Its consistence has undergone profound modifications. It is no longer a firm resistant tissue, difficult to tear or to cut. It has be come soft and friable and often exhibits a tendency to change into a pultaceous mass. Finally at autopsy we may find ruptures of the muscular tissue produced as a consequence of the inflammation. Where these ruptures have occurred there is seen to be an extravasa tion of blood, and not infrequently more or less extensive clots.
The microscope reveals an atrophy, or even a complete absence, of the striated fibres. The two principal alterations are granular and waxy degeneration. The connective-tissue elements proliferate; the embryonal cells become organized. Occasionally a cure is brought
about either by the formation of a fibrous cicatrix or by the regener ation of the muscular tissue itself, as has been observed by 0. Weber and Hayein. In this case the nuclei of the sarcolemma proliferate and give rise to embryonal muscular fibres which in turn gradually develop and end by replacing those destroyed by the inflammatory process.
But the course followed by a myositis, as regards its anatomical changes, is not always the same as here indicated. Under the influ ence of causes which it would be difficult to state with precision, among which we should have to take count of a special virulence of the infecting germ and a peculiar weakness of the soil, suppuration takes place. It is then especially that we see yellowish, grayish, or even greenish discoloration of the muscular tissue. Most frequently the formation of pus is preceded by ecchymosis and infiltration of the tissue with a black pitch-like blood. The pus contains, in addition to numbers of red blood corpuscles, a quantity of detritus coming from the connective tissue and from the disintegration of the muscular fasciculi.
The brief description which I have given applies to cases of acute myositis. When the inflammation passes into the chronic stage, the first sign that strikes the attention of the observer is the altered color of the tissue. The tint is much less pronounced; the muscle is no longer red, but rather pink or whitish. It is of greater consis teuce. There is a peculiar induration of the part which is due to the fact of an abundant proliferation of the connective tissue at the ex pense of the muscular elements.
I ought also to mention the occasional formation of calcareous deposits in the substance of the muscular tissue.
Alongside of the lesions of the muscles, in a great number of cases we note other morbid localizations. The lungs may be con gested, especially at the bases. Occasionally congestions of the liver and of the kidneys have been found, and in two cases reported by Brunon the spleen was soft, black, and increased in size.
Symptomatoloyy. —This chapter is somewhat complex and I shall find myself obliged to divide it into several parts, in order to give a clear description of the different forms of primary myositis. This affection may present itself under one of two main forms, acute and chronic, which are very distinct one from the other in their symp tomatolog,y. We will begin with the former.