Yehia Y. Mishriki, M.D.

Month: November 2021

Diagnostic pitfalls

“Remember, diseases don’t read books.”
Yousri Youssef Mishriki, MD

“Uncommon manifestations of common diseases are more common than common manifestations of uncommon diseases.”
Yehia Yousri Mishriki, MD

Why can diagnosis in medicine, at times, be so difficult?

Here is a paraphrase of a typical sentence in my internal medicine textbook when I was a student/resident – “In disease x, one finds an elevated white blood cell count. At times, however, the white blood cell count can be normal or low.”

It would not suffice to know the breadth and depth of medicine, which is impossible, to always correctly diagnose one’s patients but one must also be aware of the variability of presentation of all those diseases. Sir William Osler knew as much when he wrote his epic book, ‘The Principles and Practice of Medicine’ in 1892 wherein he described the various ways in which typhoid can present and cautioning that, “This diversified symptomatology has led to many clinical errors…”. The more modern medical literature also describes the varieties of ways diseases can present atypically. For example, Cushing syndrome, due to excess cortisol production, has occasionally been described as “cyclical” rather than continuous, with variable other presentations such as periodic hormonogenesis, unpredictable hypersecretion of cortisol, fluctuating cortisol excretion or intermittent Cushing syndrome. Even in monogenetic illnesses, where one would expect a stereotypical presentation, there can be a variability of presentation due to environmental effects and exposures, post-zygotic mutations, and epigenetic influences.

In his book, ‘Thinking Fast and Slow’, Daniel Kahneman described two methods of thinking when making decisions. In the fast pathway, pattern recognition is fast, intuitive, and often driven by heuristics (cognitive shortcuts for reaching immediate solutions to a problem) and is primarily subconscious. In the slow, analytic pathway, thinking is deliberate, effortful and under conscious control. Physicians toggle back and forth between these two methods depending on the details of the cases they are analyzing, their experience and knowledge and their whim. Tversky and Kahneman posited that most inferential errors produced by heuristics and biases were due to “faulty probabilistic reasoning”. However, Jain did not agree that the diagnostic process was probabilistic, and I believe that he is, at least partially, correct. Nevertheless, once an initial diagnosis comes to mind as a result of a heuristic, biases are bound to arise, particularly anchoring and confirmation biases which interfere with one’s ability to objectively proceed with the evaluation. Furthermore, one must simultaneously avoid the diametrically opposed biases of representativeness restraint, a tendency of looking for typical manifestations of a disease while ignoring atypical variants (“when you hear hoof beats, think of horses and not zebras”) and aggregate bias, a belief that general population data do not apply to one’s patient. A setting for cognitive dissonance, if ever there was one.

What are clinicians to do? Those in the know recommend cognitive bias mitigation which involves “deliberate switching” from intuitive to analytical processing and the use of “debiasing strategies”, what I term ‘metacognition’ or thinking about one’s thinking. After one has generated an initial possible diagnosis or diagnoses, one must step back and carefully question oneself as to whether one has fallen prey to some of the more common biases. Needless to say, this is time consuming, and time is a very rare but critical commodity in accurately diagnosing one’s patients.  


“The first figure of a physician to stand out clearly from the mists of antiquity”

Sir William osler

You may have noticed that this website has an ancient Egyptian motif. The hieroglyph and statue are both of Imhotep (“He who comes in peace”), circa 2667-2600 BC.                             

In 2012, I read an article in Consultant 360 titled, “Imhotep: The Physician/Architect Who Led Us From Magic to Medicine.” As I was baptized in the Coptic Catholic church, I have always believed that the Copts are descendants of the ancient Egyptians and, therefore, strongly felt the link to Imhotep. Unfortunately, “proof” that the Copts are the descendants of the ancient Egyptians is somewhat controversial. Nevertheless, there are genetic (i.e., the Akhenaten gene) and linguistic links from the Copts to the ancient Egyptians.

Furthermore, searching for evidence of Imhotep’s medical credentials has proved to be elusive. When I went back to review the paper from Consultant 360, I noticed that there was no author. In addition, the first citation I looked up from that article did not exist. The Dictionary of World Biography states, “while the specific qualifications of Innotek (Imhotep) as a healer are not as clearly documented, it is thought that his duties as a priest who was regarded as a magician may have initiated his reputation as a medical man.” Even the Wikipedia page dedicated to Imhotep found the claims for his having been a physician unreliable. What does stand scrutiny, however, is that Imhotep was the chancellor to the Pharaoh, Djoser, architect of the step-pyramid at Saqqara and royal astronomer. So great was respect for Imhotep that he was deified a few centuries after his death. The first mention of his medical credentials dates to 2,200 years after his death.

Much of what is known about ancient Egyptian medicine is found in a handful of papyrus rolls. These have included the Ebers Papyrus, the Hearst Papyrus, the Berlin Medical Papyrus, the Kahun Medical Papyrus, the London Medical Papyrus, the Edwin Smith Papyrus and another papyrus in Berlin. The most important of the papyrus rolls is the Ebers Papyrus, written circa 1550 BC. It is believed to be a compilation of older writings but parts of it existed during Imhotep’s lifetime and could reflect his approach to medicine and magic. The Edwin Smith Papyrus has also been proffered as “proof” that it reflects a rational evidence-based approach to medical healing. In it the text instructs the physician to examine the patient and elicit physical signs that may indicate the prognosis. Unfortunately, while the front of the papyrus deals with the care of wounds, beginning with the head, the verso has magical spells to exorcise demons.

In the book, Hippocrates Now. ‘Father of Medicine’ in the Internet Age, Helen King puts forth a conjecture that the recent desire to label Imhotep ‘Father of Medicine’ in the place of Hippocrates is “to reverse a valorization of West over East which has been common in histories of medicine into the twentieth century.” Certainly that has also been true with regards Chinese medicine and scientific advances, often superior to Western thought and technology of past eras, but which have only come to be acknowledged in recent decades.

Two final points. First, I was taught and I did teach the Hippocratic tenet, ‘Primum non nocere‘ (First do no harm). This aphorism is not found in the Hippocratic oath as such, although not causing harm is. More recently, I have taught a modern version, “Saltem plus boni, mali efficare conare” (At least try to do more good than harm). Interestingly, ‘Primum non nocere‘ is Latin whereas Hippocrates was Greek. Second, the 1946 book Hippocratic Wisdom by William Petersen, gives this advice, “Why bother with Hippocrates when there is so much to learn in modern texts? Because today, as never before, knowledge of the historical continuity of the tradition that combines theory and practice is indispensable. The student obtaining knowledge and skill only at the top levels of the modern medical skyscraper should know something of the foundation structures and the service plants in the basement and sub-basement if he is to be something more than a technician.” Sage advice.

Medicine’s Roots are Inviolable

For many, Medicine is a calling. I knew I wanted to be a doctor when in my early teens. This was reinforced by the fact that my father was a doctor who, sometimes, discussed his pathology cases at home. The depth and breadth of what he knew was breathtaking and who would not want to be so immersed in and knowledgeable of one’s profession.

Caring for patients can be, simultaneously at times, the most exhilarating, invigorating, edifying, heart warming or heart wrenching experience. At times it can be positively spiritual. It is also, on occasion, maddeningly frustrating and, sadly, the frustrating aspect has been progressively less due to difficult patient interactions and more and more due to the environment in which medicine is practiced.

I have said, and still believe that a doctor should love his or her patients. They become a part of the family and, just as with any family, there will occasionally be that difficult uncle or cousin who drives you mad. Nevertheless, he or she is still your relative and you love them nonetheless.

Forty years since receiving my degree, I have learned and experienced much more than I would have ever imagined, and a significant part of it has not been directly related to the narrow practice of medicine.

I am currently somewhat pessimistic about Medicine’s trajectory. I can see no fruitful remedy unless it comes from doctors and not the bureaucrats, big pharma and/or the government who currently hold the reins. Nevertheless, our patients continue to need us, probably more than ever, and this should be our guiding light.

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