7 Another explanation given by Kussmaul, and likewise based upon experiments on the cadaver, is that when the stomach is over-distended it may rotate upon its own axis, so that the pylorus acquires a sagittal direction and impinges against the first part of the duodenum. This rotation of the stomach, however, can occur only when the abdominal walls are flabby (Kussmaul, "Die Peristaltische Unruhe des Magens," Volkmann's Samml. klin. Vortr., No. 181).
The manner in which stenosis of the pylorus causes dilatation of the stomach is sufficiently obvious to require no especial explanation. It is, however, important to know that stenosis of the pylorus may be compensated, so that even a very considerable degree of obstruction of this orifice may exist without any dilatation of the stomach. The obstruction may be completely counteracted by hypertrophy of the muscular coat of the stomach, particularly of that in the right half of the organ. Leube suggests that this increased muscular force, by increasing the peristaltic movements, may also hasten the digestion and absorption of the food, so far as these processes take place in the stomach.8 The timely removal of the contents of the stomach by vomiting may also prevent over-distension of the organ. Another compensatory circumstance may be the reduction of the quantity of solid and liquid food taken by the patient. Conditions are often present, however, which oppose the development of these compensatory circumstances. Such conditions are feebleness of the patient, degeneration of the muscular coat of the stomach, chronic catarrhal gastritis, insufficient secretion of gastric juice, and delayed absorption, causing stagnation and fermentation of the food in the stomach.
8 Leube, in V. Ziemssen's Handb. d. spec. Path. u. Ther., Bd. vii. 2te Hälfte, p. 211, Leipzig, 1878.
Dilatation of the stomach may occur without any obstacle to the evacuation of the gastric contents into the intestine. The cases of so-called atonic dilatation of the stomach belong to this class. The degree of dilatation in these cases is rarely so great as when the dilatation is caused by stenosis. The cause of gastric dilatation in the absence of stenosis is not always clear, so that a variety of hypotheses, more or less probable, have been broached to explain these obscure cases.
Dilatation with unobstructed outlet of the stomach must be referable either to abnormalities in the quantity or quality of the contents of the stomach or to weakness of the muscular walls of the stomach. In most cases both of these causes are combined, and it is not easy to separate their action.
Abnormal gastric contents may be the result of improper ingesta or of disturbances in gastric digestion. Although in former times the frequency of excessive eating and drinking as a cause of dilatation of the stomach was doubtless exaggerated, nevertheless the efficacy of this cause cannot be doubted. Dilatation of the stomach is said to be common in people who live almost exclusively upon a vegetable diet and therefore require large quantities of food. The habitual drinking of large quantities of beer may cause dilatation of the stomach. The occasional association of a dilated stomach with diabetes is referred to the inordinate appetite and thirst which characterize this disease. If the food reaches the stomach imperfectly masticated, the process of digestion is delayed, and as a result the stomach may become dilated. Indigestible food, particularly that which readily ferments in the stomach, may be an indirect cause of the disease under consideration. A similar rôle may be played by swallowing foreign substances either by accident or by design. It is not proven that dilatation of the stomach may be referable to exhaustion of its muscular power by the abuse of agents which at first excite peristalsis, such as emetics, purgatives, alcoholics, tobacco, spices, etc. Equally doubtful is the production of dilatation by the misuse of narcotics, such as opium, which restrain peristalsis.
Of great importance in the production and continuance of gastrectasia are all circumstances which cause stagnation and fermentation of the contents of the stomach. These abnormalities of the gastric contents are referable both to muscular and to chemical insufficiency of the stomach, but in this connection it is desired to call attention especially to chemical insufficiency, although in the production of gastric dilatation this becomes always associated with muscular insufficiency. In this way chronic catarrhal gastritis is operative in the causation of gastric dilatation. In consequence of insufficient secretion of normal gastric juice and of delayed absorption, the food remains abnormally long undigested in the stomach, and fermentative changes, with the development of gas, occur. No less important, however, is the impairment of the muscular power of the stomach in chronic gastritis. Stagnation and fermentation of the contents of the stomach occur also in functional or atonic dyspepsia, which is to be reckoned as a cause of dilatation of the stomach. Naunyn9 emphasizes especially the importance of abnormal fermentations in the stomach (alcoholic, butyric acid, lactic acid, acetic acid fermentations) both as a cause and as a result of dilatation of the stomach. Ulcer and cancer of the stomach may cause dilatation by interfering with the normal digestive processes.
9 Deutsches Arch. f. kl. Med., Bd. 31.
We come now to the third and final group of causes of dilatation of the stomach—namely, those included under weakness of the muscular walls of the stomach. In the last analysis all causes of gastric dilatation come under this heading, for even with pyloric stenosis and with excessive contents a stomach will not dilate so long as its muscular power is equal to the proper performance of the work which is demanded. In this connection, however, reference is had especially to those cases in which impairment or restraint of the muscular movements of the stomach may be regarded more or less directly as the primary cause of dilatation of the stomach.
Clearest of comprehension are those cases in which the muscular power of the stomach is impaired by organic changes in the muscular coat. Here may be mentioned partial destruction of the muscular coat, particularly of that in the pyloric region, by ulcers and by cancers. Thus, ulcers and cancers which in no way obstruct the outlet of the stomach may cause dilatation of the organ. Inflammatory infiltration (inflammatory oedema) of the muscular coat has been adduced as a cause of its weakness in chronic catarrhal gastritis and in peritonitis. Whether this is the proper explanation or not, there is no doubt that the muscular coat of the stomach may become paretic in cases of chronic catarrhal gastritis, as well as the subjacent muscle in inflammations of other mucous membranes, as in laryngitis or in cystitis. Our knowledge of the relation between degeneration of the muscular coat of the stomach and gastrectasia is very imperfect. Fatty and colloid degeneration of the muscle of dilated stomachs is probably to be interpreted as a secondary change. It is probable that amyloid degeneration may be a cause of atonic dilatation of the stomach.10 Oedematous infiltration of the coats of the stomach in cases of cirrhosis of the liver, pulmonary emphysema, cardiac disease, and Bright's disease has been assigned as a cause of gastric dilatation, but without satisfactory evidence. Chronic interstitial gastritis (cirrhosis of the stomach) is more frequently a cause of contraction than of dilatation of the stomach.