PLEITRISY Occurrence and Etiology.—Pleurisy is less frequently met with during childhood than pneumonia; but at the same time it is a disease seen at all periods of life. It occurs in an acute, subacute, and chronic, and in a fibrinous, serofibrinous, and librinopurulent or purulent, form (empyema). The serofibrinous form is relatively rarer than in the adult. The purulent pleurisy, on the other hand, is much more frequent, and demands our principal interest since on its timely diagnosis and treatment the life of the patient often depends. From one-third to one-half of the pleuritic effusions in children are purulent; in adults only one-fifteenth to one-sixteenth (Netter). The reasons therefore we will ascertain directly.
The disease may occur at arty age. Even in the newborn it is met with as a symptom of sepsis. It is not infrequent from the third to the sixth month, and from that time on it is quite extensive. The younger the child the more apt is pleurisy to appear in the purulent form. Two-thirds of all cases of empyema (out of a total of 642 cases) were observed during the first 5 years of life, one-fourth from the sixth to the tenth year, and one-tenth from eleventh to fifteenth year. Of 145 cases of empyema 46 occurred during the first. year, 30 during the second, 22 during the third, 16 during the fourth year of Efe (Netter). From the sixth to seventh year and upwards the serofibrinous effusions predominate.* Boys are more often affected than girls. This depends on the fact that croupous pneumonia, the most important cause of pleurisy, is more frequent in boys, The frequent connection with croupous pneumonia may be largely influenced by the prevailing occurrence of pleurisy between the months of January and 5lay. As accessory factors colds are sometimes mentioned, less frequently trauma.
Pleurisy often occurs as a primary disease. The majority of these eases depend upon pneumococci, in which no doubt the primary pneu monic focus may occasionally have been overlooked. Nevertheless, primary pneumococcic pleurisies undoubtedly do occur, just as these bacteria may cause primary arthritis or peritonitis. According to the
experiments of Arnold and Grawitz with inhalations of dust one can readily understand how the pneumococci may migrate through the lung.s into the pleural cavity, at the same time allowing the lungs to remain intact.
In the majority of eases, pleurisy appe.ars as a secondary affection. Most frequently in affections of the lungs more than elsewhere, in croup ous pneumonia (metapneumonia), then in bronchopneumonia, bron chitis, gangrene of the lungs, etc. Pleurisy is met with as a result of pulmonary tuberculosis less frequently than in adults, and is mostly fibrinous or serofibrinous in character, and often simulating the primary form. Then again the cause may depend upon ulcerations and inflam mations of neighboring organs (bronchial glands, pericarditis, caries of the ribs and vertebne, peritonitis, and especially perityphlitis (Wol brecht), or upon acute infectious diseases, especially in .scarlet fever, then in angina (Grober), diphtlimia, grippe, measles, whooping-cough, typhoid fever, erysipelas, variola, acute rheumatism, intestinal or general sepsis, acute osteomyelitis, etc., as well as in nephritis and syphilis.
recent years the bacteriology of pleurisy has been much advanced. In the fibrinous and serous forms, bacteria are more frequently found in the culture test than was formerly supposed, though often in such small numbers that they may be regarded as being partly accidental and not as causative factors. Generally, pneumococci are present: less frequently, staphylo- and streptoeoeei, or tubercle bacilli. Schkarin also constantly found micro-organisms in the serous or serofibrinous pleurisies of nur.slings, pneumococcus in pure culture in two-thirds of the cases. EtTusions which are apparently free from bacteria are often tuberculous in character, and by inoculation of animals tubercle bacilli are usually demonstrable.