Apart from the varieties arising during life, and which alone interest us here, the invaginations formed at the cleath-agony are to be distin guished. These arise at the last hours of life, under the influence of irregularities of peristalsis, and show, on post-mortem investigation, no reaction of inflammatory nature.
According to the portions of the intestine invaginated in each other, one distinguishes ileocecal, colic, ileocolic and iliac intussuscep tions, the nature of which is indicated from the names without further description. These various forms differ in frequency, thus, for example, in children the ileocecal type is most common. (It includes according to Leichtenstern 44 per cent., Clubbe 70 per cent., arise! 82 per cent., and to Wiggin 89 per cent. of the cases.) Grisel, who has made thorough studies of invagination in childhood, gives the frequency of other types of intussuseeption as follows: ileocecal 11 per cent., small intestine 5 per cent. and large intestine 2 per cent.
As laas already been mentioned, the traction which the mesentery, included in the intussusception, exerts, limits its extent in its long axis, and further produces, at the neck of the invagination, signs of strangu lation ancl inflammation of the parts of the intestine involved; and, in consequence of this, partial adhesions are produced, and thns, like wise, further progress is prevented. The more acutely the invagination is formed the shorter it is. The length of the invagination depends, also, upon the portions of the intestine concerned. Thus, for example, the ileocecal intussusceptions are by far the longest; the head of these invagittations may extend into the rectum or be prolapsed from the anus, and there are some of this kind which have invaginated the whole of the large intestine. Next to these are the intussusceptions of the colon, while those of the small intestine are the smallest, but these, however, produce more often the double or triple intussusceptions.
The great frequency of invagination during childhood bespeaks a particular and especial disposition at this age. The greatest number of cases occur during the first six years of life. All statistics indicate that
boys are more often concerned (about three times as frequently as girls). The slight attachment of the eccum in the iliac fossa, the active peris talsis, the weak development of the musculature and of the elastic tissue of the intestinal wall, render the invagination of single parts of the intestine into neighboring folds easier in childhood than in later life. Moreover, the influence of race seems to play a part, since, in contra distinction to the large number of contributions which come from England and America, the reports from Germany, France and Austria are. much less frequent, notwithstanding a greater tendency to write in these countries. Riddell has recently pointed to the occurrence of invagination in families; lie observed the affection in three brothers and sisters.
To these predisposing causes, catarrh of the intestinal mucosa, such as can be produced in consequence of improper nourishment, is added as an immediate cause; likewise, constipation furthers the development of invagination. Among mechanical injuries must. be mentioned traumata, partieularly those which strike the abdomen directly, enemata given with improper instruments, an impressive example of which I have published; tumors of the intestinal mucosa, particularly polypi, or chronic affections of the mucosa and submucosa lead to overgrowth (Lawrence). A frequent mechanical cause of the origin of intussusception occurs when Meekel's diverticulum inverts one loop in upon another, particularly when a tumor is situated at its extremity, which not infrequently occurs; Or, when particles of food are found 111 its lumen and which it attempts to remove by encrg,etic contractions.
The vermiform appendix acts, also, in an analogous way. Acker man, who has reported 12 observations of this kind, considers the inversion of the appendix the primary cause, and agrees witb the gen erally accepted views that the production of this condition is favored by peristaltic stiffening, due to abnormal intestinal contents, adhesions with the neighboring organs, chronic inflammatory processes of the tortuous wall, and similar conditions.