Diagnosis

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“In the fight which we have to wage incessantly against ignorance and quackery among the masses and follies of all sorts among the classes, diagnosis, not drugging, is our chief weapon of offence. Lack of systematic personal training in the methods of the recognition of disease leads to the misapplication of remedies, to long courses of treatment when treatment is useless, and so directly to that lack of confidence in our methods which is apt to place us in the eyes of the public on a level with empirics and quacks”

—William Osler 1904

Annemarie Jutel, medical sociologist at Victoria Unversity writes that "With few exceptions only the medical profession has the power to diagnose disease...Being able to diagnose is at the base of the social authority afford the doctor. It sets the doctor apart from the lay person and from other professionals, confirming the doctor’s greater knowledge and status"

There are some other professions in New Zealand who are afforded the status of being able to diagnose within their fields - physiotherapy, osteopathy, chiropractic, midwifery, nurse practitioners, pharmacy prescribers. There has also recently been the provision for self-diagnosis of COVID-19 through RAT testing.

Abbreviated History

Galen 129-216

Galen was a prodigy having written three books by the age of 13. He was reported to have been incredibly arrogant. He did anatomical studies on animals, some correct but many incorrect deductions. For example he described the rete mirabilis of the brain of a calf and assigned it to a vital physiological role in humans - but it doesn't exist in humans. He made incorrect deductions about the circulatory system. However he made correct deductions about spinal injuries and devised that the brain not the heart was in charge of the body.

Galenism became holy writ, and later part of Church dogma. He championed blood letting (laudable pus) and used the theory of opposites called Contraria Contrariis. A famous quote from the time is "Christ as a second and neglected Galen.”

Critics of “Galen’s grand plan” risked severe penalties. The grand plan was one that only he could recognise, and so after his death progress in medicine essentially stopped for 1,500 years.

Vesalius 1514-1564

Vesalius broke the dogma of Galenism. He studied anatomy through human dissections (previously disallowed). The human body rediscovered. He published a highly influential work called De Humani Corporis Fabrica Libri Septum.

He drew what he saw, not what Galen told him to see, but also made some errors. For example he hadn't fathomed the mechanism of circulation, he placed the lens in the centre of the eyeball, believed the vena cava came from the liver, and thought there only to be 7 cranial nerves.

Through Vesalius the anatomical view of body developed. This was the foundation of modern medicine. Others followed suit.

Sydenham 1624-1689

Sydenham brought about the classification of disease. He was committed to naming disease to enable communication between doctors and between doctors and students.

“All diseases then ought to be reduc’d to certain and determinate kinds, with the same exactness as we see it done by botanic writers in their treatises of plants”

—Sydenham

Morgagni 1682-1771

Morgagni founded the idea of patho-anatomical correlation through a publication of >500 autopsies in his book the sites and causes of disease in 1761. He compared diseased organs with normal ones and linked symptoms to abnormalities in the body. He made classic descriptions of angina, myocardial infarction, subacute bacterial endocarditis, strokes (lesion of cerebral blood vessels), hemiplegia due to a lesion on the opposite hemisphere of the brain.

Through morgagni we got the idea that physical diseases have physical causes, often in specific organs and tissues. The humoral theory was demolished.

Paris and German Schools of Medicine

Through the Paris school we had physical examination (including percussion and mediate auscultation), psychological assessment, and autopsies became routine for clinico-pathological correlation.

In the German school we had the likes of Virchow who propounded the cellular theory pathology and Koch.