RHEUMATIC MYOSITIS - DISEASES OF THE MUSCLES.
I remarked above, when speaking of acute primary myositis, that certain authors regarded this as belonging to the class of rheumatic diseases. Indeed we are always tempted to refer muscular inflamma tions to the agency of the rheumatic poison. I believe, however, that there is an independent acute primary myositis, such as has been described above, and that apart from this there is a rheumatic myositis such as we shall now study. Inflammations of this charac ter affect both sexes and all ages, and accompany or alternate with other manifestations of the disease. This fact and that of heredity are the main points upon which we may base a diagnosis.
Rheumatic myositis may be acute, subacute, or chronic. Changes of temperature play an important part in the etiology of the individ ual attacks, and we thus find them of more frequent occurrence dur ing warm weather. At this time the skin is more active, and one is more exposed to sudden chills from checking of the perspiration. Overwork and fatigue are also to be classed among the etiological factors.
The pathological anatomy of rheumatic myositis is not well un derstood. The occasion for making an autopsy on a subject of this disease seldom presents itself, and it has been disputed that there are any material lesions of the muscle. However, Hayem has exam ined the muscles of several persons who have died during the course of acute articular rheumatism, and has found the muscular fibres rigid, swollen, and slightly granular. Other observers have stated that waxy degeneration was present. Suppuration does not ordi narily occur in this form of myositis, though it might exceptionally take place. The most important lesion occurring in rheumatic myo sitis is atrophy of the muscle or muscles affected.
Symptoms.—The acute form of rheumatic myositis is accompa nied by very severe pains which the slightest movement excites. Oc casionally, though rarely, there is an elevation of temperature of short duration. The affected muscle may be in a state of contraction.
Usually the inflammation involves but few muscles. The best exam ples of rheumatic myositis which I can cite are the inflammation of the sterno-cleido-mastoid, otherwise known as torticollis, and that of the clorso-lumbar mass which goes under the name of lumbago.
Chronic rheumatic myositis is a very common affection, and we may say that the great majority of cases of chronic myositis not fol lowing the acute form are of rheumatic origin. In this case we find the muscles more or less indurated and often shortened. The pain is not so severe as in the acute form, hut it nevertheless constitutes an important symptom. The patients suffer from movements, and furthermore pain is excited, as in other rheumatic conditions, by various meteorological changes, sncli as a lowering of the tempera ture of the atmosphere, variations in barometric pressure, changes of electrical tension, etc.
The diagnosis of rheumatic myositis involves a consideration of two points: (1) Have we to do with an affection of the muscles; and (2) is it of rheumatic nature? We (-an satisfy ourselves as to whether the muscles are affected by means of careful palpation of the parts, mapping out exactly the limits of the painful region; in this way we may easily exclude other causes of suffering, such as neuralgia, by observing that the pain is felt in greatest intensity in the body of the muscle and at its points of insertion, and not along the course of one of the main nerve trunks. In regard to the second point we must base our opinion upon the hereditary and personal antecedents of the patient. We should remember also that the temperature in rheu matic myositis, even in the most acute forms, is seldom elevated to any great extent, and that suppuration is an absolute rarity.
The prognosis is in general favorable; nevertheless we should not forget that chronic myositis may persist for a very long time and may be the cause of atrophy of the muscle.