SECONDARY MYOSITIS - DISEASES OF THE The muscles may became inflamed in consequence of a large num ber of influences acting upon them from without. In the first place an inflammation which is primarily limited to a certain region, to one tissue or one organ, may advance slowly and gradually involve the neighboring muscles, giving rise to what has been called " my ositis by propagation." The best example that I can give of this form of myositis is the inflammation which is developed in a muscle in close relation with an inflamed articulation. It is a common observation in cases of arthritis to see, simultaneously with the joint affection, painful symptoms limited to the group of muscles in close proximity to the affected articulation. Examination also shows a certain de gree of induration in the affected muscle, and, in the course of time a more or less pronounced atrophy resulting from the long-continued chronic inflammation.
The inflammatory process may travel from any focus whatever and invade the neighboring muscular tissue. In very many cases of sec ondary myositis more even than in the primary disease the symptoms are often masked by those of the more important disease and thus pass unperceived.
Alongside of myositis by propagation we may mention a "toxic myositis." We are still very much in the dark as to the inflamma
tory action that poisons are capable of exciting in muscular tissue. I refer here, of course, to mineral or vegetable poisons, leaving out of consideration the microbial poisons or toxins, upon which we pos sess as yet but few data. These toxic substances certainly exert an injurious action upon the muscles, but this is chiefly of a trophic nature, and its consideration must be reserved for a later section. We might mention here only the acute steatosis, referred to by Hayem, which occurs. in the muscles under the influence of poisoning by phosphorus, although, strictly speaking, there is no inflammatory process here present. Cornil has noted the occurrence of the lesions of diffuse myositis in a case of poisoning by ammonia.
As one may see, our knowledge of this subject is still very incom plete, and we must rely upon time to fill up the parts that are want ing. 'We know much more of the form of secondary myositis of which I now propose to speak, iu which the muscular lesions are produced in the course of an acute or chronic general disease. This variety of muscular disease I would call