ETIOLOGY.—Dilatation of the stomach is the result of inability of this organ to propel its contents into the intestine within the normal space of time. In the performance of this mechanical work three factors are involved—namely, the muscular force of the stomach, the quantity and quality of the gastric contents, and the size of the opening between the stomach and the intestine. All causes of dilatation of the stomach may be referred to abnormalities of one or more of these factors.
The most important group of causes is represented by stenosis of the pyloric orifice or of the adjacent part of the stomach or of the intestine.4 Most cases of hypertrophic dilatation of the stomach—that is, dilatation with hypertrophy of the muscular walls of the stomach—are produced by causes belonging to this group.
4 Dilatation of the stomach in consequence of intestinal obstruction below the duodenum is so rare that no further attention is given to the subject in the present article. The term pyloric stenosis is often used in the course of the article to include any obstruction to the passage of the contents of the stomach into the intestine, whether the obstruction be in the duodenum, the pyloric orifice, or the pyloric region.
The most frequent cause of pyloric stenosis is carcinoma, either in the form of a diffuse infiltration of the gastric walls in this region or as a tumor projecting into the cavity of the pyloric portion of the stomach. Next in frequency are cicatricial growths resulting from simple ulcer involving the pyloric region. Much less frequent are similar cicatricial stenoses of the pylorus resulting from ulcers produced by swallowing corrosive poisons. Simple hypertrophy of the coats of the stomach in the pyloric region, particularly of the fibrous and muscular coats, is an occasional cause of dilatation. Obstruction of the pylorus by mucous polypi or by hypertrophic folds of mucous membrane is so rare as to have little practical interest. Likewise, stenosis caused by sarcomata, fibromata, myomata, lipomata, and cysts need be mentioned only for the sake of completeness.
Narrowing of the pyloric orifice may be caused also by pressure from outside of the stomach, as by tumors, particularly cancer, of the liver and of the pancreas, and by the contraction of fibrous adhesions and thickenings resulting from perigastritis. Obstruction of the duodenum by tumors growing in its walls, by cicatrices resulting from ulcers, and by external pressure may also cause dilatation of the stomach. According to Barker, compression of the duodenum by a wandering right kidney may induce dilatation of the stomach. The mere association of dilatation of the stomach and movable right kidney, however, cannot be considered proof that the former is caused by the latter, for the subjects of movable kidney (most frequently women with flabby abdominal walls who have borne many children) are often also favorable subjects for atonic dilatation of the stomach.
Sometimes with dilatation of the stomach the pyloric orifice is found abnormally small, without any thickening or other appreciable change in the walls of the pylorus. These cases in adults have been described by Landerer under the name of congenital stenosis of the pylorus, but his conclusions are not free from doubt.5 Congenital stenosis, and even complete occlusion of the pylorus, has been observed in infants.6
5 Ueber angeborene Stenose des Pylorus, Inaug. Diss., Tübingen, 1879. In the ten cases studied by Landerer the patients were all adults, mostly in advanced life. In only one case is it mentioned that indigestion existed from childhood; the clinical history in all is incomplete. With the exception of one case there was no marked hypertrophy of the muscular coat of the stomach, such as is usually found with benign pyloric stenosis and would naturally be expected with a stenosis existing since birth. The pyloric orifice varied from 1½ cm. to 2 mm. in diameter. Some of the specimens had been in alcohol for a considerable time. In my opinion, Landerer has not brought forward sufficient proof that in these cases stenosis of the pylorus existed since birth.
6 Wünsche, Jahrb. d. Kinderheilk., viii. 3, p. 367. Andral, Förster, and Bull have found congenital stenosis and atresia of the pylorus.
Spasm of the pyloric muscle, which, according to Kussmaul, may be referable to erosions, ulcers, and inflammations of the adjacent mucous membrane, can be admitted only as a hypothetical explanation of some cases of dilatation of the stomach.
Somewhat problematical, although not improbable, is the production of stenosis of the pylorus or of the duodenum by torsion and by displacement of these parts. Dilatation of the stomach is sometimes associated with scrotal hernia, particularly with that containing omentum or transverse colon. This dilatation Kussmaul explains by the production of a sharp bend between the movable first part and comparatively fixed second part of the duodenum, in consequence of the dragging downward of the stomach by the displaced omentum or transverse colon. In a similar way Kussmaul believes that the weight of an over-distended stomach may produce stenosis, and by this mechanism he explains the occasional occurrence of symptoms of complete pyloric obstruction when a large quantity of material has accumulated in an already dilated stomach, and the prompt relief of these symptoms when the burden of the stomach is removed either by vomiting or by the stomach-tube.7