Gastric ulcers have been produced experimentally in animals in a variety of ways, but these experiments have not materially elucidated the pathenogenesis of ulcer in man. Schiff by lesions of various parts of the brain, and later Ebstein by lesions of many parts of the central and peripheral nervous system by injections of strychnine—in fact, apparently by any means which greatly increased the blood-pressure—produced in the stomachs of animals ecchymoses and ulcers. Müller by ligation of the portal vein, Pavy by ligation of arteries supplying the stomach, likewise produced hemorrhages and ulcers. The results of Pavy could not be confirmed by Roth and others. Panum, and afterward Cohnheim, produced gastric ulcers by introducing multiple emboli into the gastric arteries. Daettwyler under Quincke's direction caused, in dogs with gastric fistulæ, ulcers of the stomach by various mechanical, chemical, and thermic irritants applied to the inner surface of the stomach. Aufrecht observed hemorrhages and ulcers in the stomachs of rabbits after subcutaneous injections of cantharidin.100
100 Schiff, De vi motorea baseos encephali, 1845, p. 41; Ebstein, Arch f. exp. Path. u. Pharm., 1874, p. 183; Müller, Das corrosive Geschwür im Magen, etc., p. 273, Erlangen, 1860; Pavy, Guy's Hosp. Rep., vol. xiii., 1867; Roth, Virchow's Archiv, Bd. 45, p. 300, 1869; Panum, loc. cit.; Cohnheim, op. cit.; Daettwyler, Quincke, Deutsche med. Wochenschr., 1882, p. 79; Aufrecht, Centralbl. f. d. med. Wiss., 1882, No. 31.
The most interesting of these experiments are those of Cohnheim and of Daettwyler, who demonstrated that in one essential point all of these experimental ulcers differ from simple gastric ulcer in man—namely, in the readiness with which they heal. To this ready healing the gastric juice, much as it has been accused of causing the spread of gastric ulcers in man, seems to have offered no obstacle. We know that similar losses of substance in the human stomach heal equally well.101 Hence it has been maintained throughout this article that it is unjustifiable to regard all of the scars found in the human stomach as the result of simple ulcer.
101 Portions of the mucous membrane of the stomach, sometimes with some of the submucous coat, have been in several instances removed with the stomach-pump, but thus far no bad effects have followed.
It appears from these experiments, as well as from observations on man, that it is more difficult to explain why ulcers in the stomach do not heal than it is to understand how they may be produced. From this point of view the observation of Daettwyler is of interest, that in dogs which had been rendered anæmic by repeated abstraction of blood not only did slighter irritants suffice to produce ulcers of the stomach, but the ulcers healed much more slowly. Practically, it is important to learn what are the obstacles to the repair of gastric ulcers, but our positive knowledge of these is slight. It is probable that such obstacles are to be found in constitutional causes, such as anæmia and chlorosis, in abnormal states of the blood-vessels around the ulcer, in catarrhal affections of the stomach, in irritating articles of food, in improper modes of living, and in increased acidity of the gastric juice.
DIAGNOSIS.—In many cases the diagnosis of gastric ulcer can be made with reasonable certainty; in other cases the diagnosis amounts only to a suspicion more or less strong, and in still other cases the diagnosis is impossible.
The diagnostic symptoms are epigastric pain, vomiting, and gastric hemorrhage. The characteristics of the pain which aid in the diagnosis are its fixation in one spot in the epigastric region, its onset soon after eating, its dependence upon the quantity and the quality of the food, its relief upon the complete expulsion of the contents of the stomach, its alleviation by changes in posture, and its increase by pressure. That the pain of gastric ulcer has not always these characteristics has been mentioned under the Symptomatology. Vomiting without hæmatemesis is the least characteristic of these symptoms. It aids in the diagnosis when it occurs after eating at the acme of a gastralgic attack and is followed by the relief of pain. Hæmatemesis is the most valuable symptom in diagnosis. The more profuse the hemorrhage and the younger the individual in whom it occurs, the greater is the probability of gastric ulcer. It should not be forgotten that the blood is sometimes discharged solely by the stools.
The simultaneous occurrence of all these symptoms renders the diagnosis of gastric ulcer easy.102 In all cases in which gastrorrhagia is absent the diagnosis is uncertain; but gastric ulcer should be suspected whenever the ingestion of food is followed persistently by severe epigastric pain and other causes of the pain have not been positively determined. When the course of the ulcer is latent and when the symptoms are only those of dyspepsia, the diagnosis is of course impossible. In cases previously obscure a diagnosis in extremis is sometimes made possible by the occurrence of perforation of the stomach.
102 That even under the most favorable circumstances absolute certainty in the diagnosis of gastric ulcer is not reached is illustrated by a case reported with great precision and fulness by Banti: A female servant, twenty-one years old, had every symptom of gastric ulcer, including repeated hæmatemesis and the characteristic epigastric pain. She was nourished by enemata. She died from an ulcerative proctitis four days after the last hemorrhage from the stomach. Only a slight catarrhal inflammation of the stomach was found at the autopsy, without trace of ulcer, cicatrix, or ecchymosis ("Di un Caso d'Ematemesi," La Sperimentale, Feb., 1880, p. 168). It would seem as if there must have been an ulcer which had healed so completely as to leave no recognizable scar.
In making a differential diagnosis of gastric ulcer, as well as of any disease, reliance should be placed more upon the whole complexion of the case than upon any fancied pathognomonic symptoms.