Intestinal indigestion accompanies hyperæmia and catarrh of the intestinal mucous membrane, diseases of the heart, lungs, and liver, and all other causes which impede portal circulation.

SYMPTOMS.—Intestinal indigestion cannot be so clearly pictured as that of gastric dyspepsia. This is owing to the frequent concurrence of the two conditions, the gastric symptoms taking precedence of the others. The more complex nature of the intestinal function is another reason, intestinal indigestion having more modifications in its phenomena. In the stomach there is only one active secretion; in the intestine there are three, all participants in the act of solution. An alteration in the quality or quantity of one of these—the bile, for example—would lead to different symptomatic results than would follow another defective secretion, as that of the pancreas, for instance. Clinical study has not yet fully differentiated the forms of indigestion due to these several deficiencies. But there are certain well-defined symptoms associated with intestinal disorders which are distinguished by their seat, time of their appearance, and their character from analogous symptoms connected with the stomach.

Intestinal indigestion may be acute or chronic. The latter is the more typical and more common form.

When a sudden attack of indigestion in the intestine results from the entrance into the duodenum of food in such a state that it cannot be digested, the result is the rapid development of pain, flatulence, borborygmi, and frequently of fever, ending in diarrhoea, with the escape perhaps of the offending matter: a condition then exists which may be called acute or subacute intestinal catarrh or acute intestinal indigestion. One name would be as correct as the other. Slight acute forms are marked by a coated tongue, loss of appetite, headache, pains in the limbs, distress in the epigastrium or right hypochondrium, flatulence, and constipation. These might be accompanied by symptoms indicating a disorder of the liver functions—light-colored stools, slight jaundice, lithates in the urine. But intestinal indigestion alone can cause these symptoms without the condition of so-called biliousness being present. The local symptoms are due to the presence in the intestine of an imperfectly-altered mass and the development of gas; some of the general symptoms are reflex; others, as headache and lassitude and pain in the limbs, come from the absorption into the blood of the gases, particularly sulphuretted hydrogen. The participation of the stomach in acute attacks of this sort modifies the symptoms as here described. Such attacks are apt to recur at intervals.

If the causes which bring about acute disorder in the intestine are allowed to continue, the intervals between the acute or subacute attacks diminish, and there is in time a fixed state of chronic intestinal dyspepsia in which the partly-altered food coming from the stomach is not properly prepared for absorption. Instead of digestion there is decomposition; the transition is easy from the one to the other of these states. The symptoms connected in this case with the digestive organs are pain, occurring from two to six hours after eating, in the right hypochondrium, the epigastrium, or the umbilical region, due to distension of the intestine with gas. This pain is dull, not always fixed, lasts from one to three hours, and is accompanied by tenderness on pressure over its seat.

Tympanites, borborygmi, and a sensation of fulness in the abdomen accompany the pain or may exist without it. Gaseous accumulations in the intestine, the cause of these symptoms, have an independent source, being produced by decomposition in the gut itself, and are not due to the descent of gases from the stomach through the pylorus. What is a physiological and temporary condition becomes in disease a distressing symptom of long duration. In intestinal indigestion the gut is nearly always inflated with gas, which in its movement produces rumbling noises. In acute indigestion it is rapidly formed in large amount, and by the stretching of the wall of the bowel and pressure on nerve-filaments causes intense pain—colic. In the chronic form the distension excites uneasy sensations, prevents sleep, and may be so great as to cause dyspnoea by pushing the diaphragm upward. When the small intestine is distended the greatest swelling may be about the umbilicus, or the abdomen may be evenly rounded. When the colon is chiefly or solely inflated, its outline across the upper part or at the sides of the abdomen can be easily made out.

Constipation is a common feature. It is produced by a loss of contractility of the intestinal wall. The more direct causes are over-distension of the gut and disturbance in the circulation and innervation of its walls. The stools are hard and dry, and are expelled with difficulty. Sometimes they are coated with shreds or films of mucus, the product of a chronic catarrh of the mucous membrane of the colon, or mucus from the small intestine is intimately mixed with the mass. Diarrhoea may alternate with constipation. The passage of unaltered food, as fragments of meat, vegetables, or fruit, clearly shows the extent to which indigestion exists. By the microscope particles of food which have escaped complete disintegration may be detected. The stools vary in color. Very dark-green or black discharges show an excess of bile; light-yellow or gray slate-colored, a deficiency. Stools of the latter character are highly offensive in odor.

Hemorrhoids are often present, being due to the sluggish portal circulation and to the pressure of hard fecal masses in the rectum. The appetite is not impaired, as a rule, but it may be fitful or irregular. A bad taste in the mouth, and a swollen, relaxed, and coated tongue may exist without any decided gastric disease.

The symptoms of disorder of the nervous system are more marked than in gastric dyspepsia. This results not so much from the depressing influences of pain as from the peculiar malnutrition of the nerve-tissue. In order to have furnished to the blood the pabulum out of which the nerve-elements are reconstructed the digestion of fat must be normally performed. Lecithin, which is found conspicuously in the brain and nerves, is a complex fat containing phosphorus and nitrogen.10 Anæmia and waste follow directly from interference with the digestion and absorption of fats and starch in the intestine, but the most delicate, the most easily-disorganized solid of the body, the nerve-tissue, is the first to feel and to manifest its want of natural supply. And so the dyspeptic whose intestine is at fault becomes depressed in spirits, hypochondriacal, absorbed in the contemplation of his sufferings, analyzing them and referring them to the most serious organic changes. There are sleeplessness, disturbing dreams, the habit of waking at a fixed hour, dizziness, uneasy sensations or pain in the head, and disturbances of the special senses, as buzzing in the ears, muscæ volitantes, and attacks of blindness. Headache assumes often the form of hemicrania; it may be in the forehead or about the eyes. Attacks of vertigo and sensations as if the ground were rising beneath the feet accompany intestinal flatulence. Confusion of thought, loss of the power of application, and mental inertia are frequent sources of anxiety. Paralysis has been noted as following indigestion. Epileptiform convulsions and milder epileptic attacks can be traced to undigested matter in the intestine.11 Various modifications of general sensibility also happen: there are pains in the back and limbs, hyperæsthesia, and anæsthesia. An inaptitude for exertion, especially for mental labor, forces the boy to give up school and college life. Successful careers are abandoned by men who at the cost of neglecting all the rules of health have succeeded for a brief period in passing their fellows in the race. Sudden attacks of fainting have been noted, with very grave collapse. These are the effect upon the nervous centres of the absorption of sulphuretted hydrogen which has been evolved in large quantities in the intestine.12 The daily occurrence of vertiginous and other morbid sensations, with melancholia, may be due to the daily toxic absorption of gas from the intestine.

10 Fothergill, Indigestion and Biliousness, New York, 1881, p. 76.