The Differential Diagnosis

I recently ran across a post on social media discussing the differential diagnosis. This is of course very familiar to those who work in the realm of injury, diagnosis, and remediation. The term is often talked about, and discussed. The Cleveland clinic explains:
“Since there are a lot of different conditions that often share similar symptoms, your provider will create a differential diagnosis, which is a list of possible conditions that could cause your symptoms.”
It then cautions that such statements are not effectively “the diagnosis," but potential explanations for whatever constellation of symptoms are presented. It is, in a nutshell, an early part of the process involved in finding a path toward recovery.
In the Case Book of Sherlock Holmes, Sir Arthur Conan Doyle’s protagonist proposes an intriguing path to the truth:
“When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.”
This, it’s not too far distant from the paradigm of the differential diagnosis. Having identified the constellation of potential explanations for a symptom or series of symptoms and complaint(s), the scientist begins to illuminate the improbabilities, through testing and examination. The process is one of elimination.
It may be troubling to patients that one of those filters is often simply the passage of time. In other words, “let’s wait to see if this resolves.“ One step short of this is the old saw "take two aspirin and call me in the morning." Grammar How explains that this phrase is 
"an expression that refers to the idea that people call doctors for issues that they can just treat themselves." 
In other words, not every malady requires a physician, and we experience this periodically in our modern society. So, while not our favorite answer, a valid answer may well be "let's see if time helps," and if it does, that may eliminate some of that spectrum of possible diagnoses.
I was privileged to attend a medical lecture at the Worker’s Compensation Institute in August 2022. The physician, Dr. Chapa, explained the risks and challenges of a mistaken diagnosis. A constellation of symptoms may point to various potential diagnoses and treatment options. When we ignore that spectrum, and immediately focus upon one singular conclusion, the result may be treatment that will not address the symptoms, and in fact may cause other symptoms or complaints.
Such an error may instigate a journey down an inappropriate path which may result in dire consequences. This may be best illustrated by another of Holmes quotes in A Study in Scarlet (1887): 
“It is a capital mistake to theorize before you have all the evidence. It biases the judgment.” 
The evidence is the key. That a malady can cause a symptom is a start. From that premise comes the launching point for the investigation, the gathering of evidence, and the elimination of possibilities, and even some probabilities, leading to a conclusion (diagnosis) that is based upon the scientific evidence. Thus, the differential diagnosis makes sense as a logic path between what may be the issue to what is probably the issue.
Because there are multiple potential explanations or causation of any particular physical complaint or symptom, it is imperative that the medical professional correctly identify the truth, rather than a probability. As Donald A. Norman is quoted: “a brilliant solution to the wrong problem can be worse than no solution at all: solve the correct problem.” The drive to "a" solution before waiting for the evidence or the science may be the patient's demand that doctors "do something." We have all had symptoms we wanted to be rid of, fortunately for most they were not debilitating, but imagine your reaction if you were suffering such significant symptoms, discomfort, pain, etc.
Perhaps we all have a bit of Verunca Salt in us (Willy Wonka and the Chocolate Factory, Warner Brothers 1971). She instructed us about her demands with "I don't care how, I want it now." When we are unwell, we all want relief. And, in fairness, we likely all want it immediately. It occurred to me in the course of the deferential discussion above, that we might refer to a rush to diagnosis and treatment as the “deferential diagnosis“ rather than "differential." The Cambridge Dictionary defines “deferential“: “polite and showing respect.”
And that’s where I might lose the reader. Stick with me. There’s nothing wrong with a medical professional being deferential, in terms of this definition of respectfulness and politeness. However, that appropriate respect for the patient must be tempered with the scientific responsibility of the practitioner to find the cause of symptoms and to provide the remediation that will best ameliorate them.
In this regard, I divert momentarily from this definition of deference to its synonyms instead. These, listed by Merriam Webster, include:
"complaisance, servility, subservience, indulgence, capitulation, submission, and surrender"
In other words, it is possible that deference may surpass politeness and cordiality and proceed to poor decisions based on assumptions and the patient's desire that the doctor "do something," despite the lack of evidence to support that conclusion. One might do harm in the process. See Hippocrates, Harm, and Racism (May 2022). 
The Holmesian suggestion of eliminating improbability‘s is suggestive and logical. The advice to hold off conclusions until the facts are known is also. The potential for doing harm (at worst) or doing no good as regards symptoms (at best) are risks. 
When the "something" that is undertaken has minimal or no risk of harm, that may be a more acceptable course. The success or failure of some medication or modality might help in the elimination of the possibilities. That is, the treatment itself may bring evidence that is helpful in the diagnostic process. However, the "something" might be more serious, such as surgical intervention with all of the attendant risks. Such serious intervention cannot be appropriately undertaken merely on the patient's whim or demand. 
Medicine owes it to the patient to be respectful of complaints and symptoms; to be “polite and show() respect.” But, additionally, to avoid the potential for further risk or damage through yielding to the inclination of some to treat first and ask questions later. There have been many examples in which a significant surgery has been completed without any alleviation of the symptoms that led to treatment. In those instances, the next step is often another surgery on different anatomy. 
The point is to address the differential process in a respectful and polite manner, but to carefully eliminate the possibilities as non-invasively as possible through care and testing. The decision for surgical intervention cannot appropriately be  based upon the mere possibility or suspicion that symptoms might be relieved. 
By Judge David Langham
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    About The Author

    • Judge David Langham

      David Langham is the Deputy Chief Judge of Compensation Claims for the Florida Office of Judges of Compensation Claims at the Division of Administrative Hearings. He has been involved in workers’ compensation for over 25 years as an attorney, an adjudicator, and administrator. He has delivered hundreds of professional lectures, published numerous articles on workers’ compensation in a variety of publications, and is a frequent blogger on Florida Workers’ Compensation Adjudication. David is a founding director of the National Association of Workers’ Compensation Judiciary and the Professional Mediation Institute, and is involved in the Southern Association of Workers’ Compensation Administrators (SAWCA) and the International Association of Industrial Accident Boards and Commissions (IAIABC). He is a vocal advocate of leveraging technology and modernizing the dispute resolution processes of workers’ compensation.

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