The People's Common Sense Medical Adviser in Plain English / or, Medicine Simplified, 54th ed., One Million, Six Hundred / and Fifty Thousand

by Ray Vaughn Pierce

Medical diagnosis is both a science and an art; a science when the causes and symptoms of a disease are understood, and an art when this knowledge can be applied to determine its location and exact nature. Science presents the general principles of practice; art detects among the characteristic symptoms the differential signs, and applies the remedy. Da Costa aptly remarks: "No one aspiring to become a skillful observer can trust exclusively to the light reflected from the writings of others; he must carry the torch in his own hands, and himself look into every recess."

The critical investigation of symptoms, with the view of ascertaining their signs, is essential to successful practice. Without closely observing them, we cannot accurately trace out the diagnosis, and a failure to detect the right disease is apt to be followed by the use of wrong medicines.

General diagnosis considers the surroundings of the patient as well as the actual manifestations of the disease. It takes into account the diathesis, i.e., the predisposition to certain diseases in consequence of peculiarities of constitution. We recognize constitutional tendencies, which may be indicated by the contour of the body, its growth, stature, and temperament, since all these facts greatly modify the treatment. Likewise the sex, age, climate, habits, occupation, previous diseases, as well as the present condition, must be taken into account.

Auscultation, as practiced in detecting disease, consists in listening to the sounds which can be heard in the chest.

Percussion consists in striking upon a part with the view of appreciating the sound which results. The part may be struck directly with the tips of the fingers, but more generally one or more fingers of the other hand are interposed between the points of the fingers and the part to be percussed, that they, instead of the naked chest, may receive the blow; or, instead of the fingers, a flat piece of bone or ivory, called a pleximeter, is placed upon the chest to receive the blow.

Latterly, improved instruments greatly assist the practitioner of medicine in perfecting this art. The microscope assists the eye, and helps to reveal the appearance and character of the excretions, detecting morbid degenerations; chemistry discloses the composition of the urine, which also indicates the morbid alterations occurring in the system; by percussion we can determine the condition of an internal organ, from the sound given when the external surface is percussed; the ear, with the aid of the stethoscope, detects the strange murmurs of respiration, the fainter, more unnatural pulsations of life, and the obscurer workings of disease; with the spirometer we determine the breathing capacity of the lungs, and thus ascertain the extent of the inroads made by disease; the dynamometer records the lifting ability of the patient; the thermometer indicates the morbid variation in the bodily temperature; various instruments inform us of the structural changes causing alterations in the specific gravity of fluids, e.g., the urinometer indicates those occurring in the urine; and thus, as the facilities for correct diagnosis increase, the art of distinguishing and classifying diseases becomes more perfect, and their treatment more certain. While physiology treats of all the natural functions, pathology treats of lesions and altered conditions.

By the term symptoms we mean the evidence of some morbid effect or change occurring in the human body, and it requires close observation and well-instructed experience to convert these symptoms into diagnostic signs. Suppose "Old Probabilities" (as we commonly designate the invaluable Signal Department) hangs out his warning tokens all along our lake borders and ocean coasts; our sailors behold the fluttering symbols indicating an approaching storm, but if no one understood their meaning, a fearful disaster might follow. But if these signals are understood, a safe harbor is sought and the mariner is protected. So disease may hang out all her signals of distress, in order that they may be seen, but unless correctly interpreted, and a remedial harbor is sought, these symptoms are of little practical value.

Undoubtedly the reason why so many symptom-doctors blunder is because they prescribe according to the apparent symptoms, without any real reference to the nature of the affection. They fail to discover how far a symptom points out the seat, and also the progress of a disease. They do not distinguish the relative importance of the different symptoms. The practical purpose of all science is to skillfully apply knowledge to salutary and profitable uses. The patient himself may carefully note the indications, but it is only the expert physician who can tell the import of each symptom.

Symptoms are within every one's observation, but only the physician knows the nature and value of signs. We have read an anecdote of Galen, who was a distinguished physician in his day, which illustrates the distinction between sign and symptom. Once, when dangerously ill, he overheard two of his friends in attendance upon him recount his symptoms, such as "Redness of the face, a dejected, haggard, and inflamed appearance," etc. He cried out to them to adopt every necessary measure forthwith, as he was threatened with delirium. The two friends saw the symptoms well enough; but it was only Galen himself, though the patient, who was able to deduce the sign of delirium—that is, he alone was able to translate those symptoms into signs. To determine the value of symptoms, as signs of disease, requires close observation.