Zebras, hoof-beats and Dr. House: Differential Diagnosis
Tuesday, June 28, 2011 11 Comments
Differential Diagnosis: WHAT is it?
and WHY do I care?
by Madelyn Griffith-Haynie,
CTP, CMC, ACT, MCC, SCAC
(To find out how the Zebras relate, read the article!!)
A differential diagnosis is one which examines all of the possible reasons for a set of symptoms in order to arrive at an identification of the cause (or combination of causes) of a presenting problem.
It’s a fairly simple process of elimination that can become unblievably complex in an eye-blink, “simply” because so many diseases and disorders present with similar symptoms,
Although the term “differential diagnosis” initially referred to issues of physical health, today many doctors in the mental health field also use this system of diagnosis.
Diagnosticians specialize in differential diagnosis.
Everybody’s favorite Diagnostician
And who would that be?
Why, House, of course!
House — the Cliff Notes:
In the popular TV show, House, a diverse team of unusually attractive doctors works under a brilliant but cantankerous head of neurosurgery in a metropolitan hospital.
Each week the team examines various symptoms and clues, looking for underlying causes that might help them figure out what is wrong and what they must do to restore the health of this week’s patient.
- This week’s patient lands in their care through a variety of unexpected means – always suddenly urgent. Both patient and problem are introduced to us at the very top of every show.
- The team immediately convenes in a sort of hospital “situation room” to play a fast round of “WHAT could possibly account for these bizarre symptoms?” as House writes each possibility on a whiteboard, crossing things out as the team argues for and against theory after theory. An initial diagnosis is agreed upon, and treatment begins urgently.
- The patient’s condition is monitored throughout the process, of course, and when he or she fails to improve – or when the condition worsens – House and team go back to the drawing board. Treatment failure becomes another clue in the process of putting the pieces together in a way that solves the puzzle. Just like in life.
Even for a crackerjack team like House, et. al, it is not uncommon to be misled, going back to the drawing board several times (literally, during each episode of this particular TV series), before a treatment protocol can be suggested with any confidence that it might be expected to work this time.
“When you hear hoof-beats, look for horses, not zebras.”
Most real-world doctors are familiar with the above quote from their medical training. It is often quoted to impress upon young med students one of the cardinal rules of “real life” differentials:
Always begin by considering the most common diagnosis first. Don’t move on to the more exotic possibilities until the simplest diagnoses have been ruled out — for legitimate, well-thought-out reasons.
Except on House, of course!
Since the producers and sponsors of House are more concerned with delivering an hour of dramatic television than providing an accurate example of the differential diagnostic process, the show’s writers ignore that particular “simplest first” caveat.
As the audience, we love to play right along. We just know that whatever is wrong with the patient with the toothache is definitely more likely to be a brain tumor than a cavity.
House “regulars” know that each episode follows a pattern:
- The team will rule out the obvious in the first fifteen minutes, brow-beaten by a scowling, scornful, addicted-to-pain-pills-but-too-brilliant-to-fire Dr. House;
- One of the team will suggest something like neuropathy right before or after the first commercial;
- Shortly before the halfway point, when the patient’s symptoms don’t quite fit the parameters of a neurological diagnosis, House’s shrink colleague and buddy will be called in to check out psychiatric issues;
- When (just before we break for another commercial) the patient almost dies, a junior member of the team will campaign for treating the patient for something cryptic – like atypical meningitis – and
- When a FATAL treatment mistake is just about to be made . . .
- ANOTHER member of the team will save the day by determining that some kind of genetic mutation has been activated by exposure to an esoteric strain of bird-flu because –
- SOMEONE else from the team was sent to investigate the home of the patient (now lingering on his deathbed) to discover that the basement is full of pigeon poop!
Yep, that’s a differential diagnosis in a nutshell!
(minus the drama, the commercials, and the pigeon poop).
A “real life” differential follows the House pattern:
- It starts by reviewing the patient’s case: beginning with the presenting problem.
- Along with examining the patient, the clinician will probably interview all concerned as s/he catalogues all the symptoms, which generally leads to
- Compiling a patient history – which provides a picture of the patient’s background, family of origin, personal quirks, hobbies and habits, social interactions and practices;
- Certain tests are sometimes ordered as part of the drill, to obtain specific information about the patient’s current condition;
- Additional interviews with friends and coworkers might be compiled in a particularly puzzling or complicated case, or when the patient isn’t able to provide adequate information for any reason;
- Other specialists are sometimes called in, to draw upon a wider body of knowledge and experience; and
- It sometimes becomes necessary to examine the patient’s environment to look for causes that nobody thought important enough to mention in this particular context.
WHY Differential diagnosis?
The most obvious answer – to make sure you’re not being treated for something that’s not the problem – is only the beginning.
IN ADDITION to identifying the source accurately, a first-rate differential diagnosis
will allow you, the patient, to:
- work with your treatment team more effectively, since everyone is clear about which condition (or combination of conditions) they are working ON;
- understand the source of your symptoms, as well as an appropriate list of interventions available to make you more comfortable and effective;
- make decisions about your future based on a realistic assessment of the progression likely with your diagnosis;
- eliminate more frightening possibilities so you can stop worrying about them
- develop an effective treatment plan;
- enable you and your loved ones to plan around your condition while you are working on strategies designed to clear up the worst of the problems
So what does all this have to do with ADD, and why should we care?
Ah, hang onto your hats - for those of us with executive functioning deficits, here’s where it begins to get dicey! [CLICK HERE for Part II]
- ABOUT ADD Comorbidities - Comorbid or Co-occuring?
- ADD Seldom Rides Alone
- Remembrance of Selves Past
- ODD & Oppositional Rising
- ABOUT ADD and Sleep Struggles
- Differential Diagnosis - distinguishing ADD from Comorbidities
- Overfocusing: Cognitive Inflexibility and the Cingulate Gyrus (Stubborn or STUCK?)
- Top Ten Stupid Comments from ADD-Docs (addandsomuchmore.com)
- Top Questions to Ask to find a GRRRRreat! ADD Doc (addandsomuchmore.com)
- Top Ten Meds questions (addandsomuchmore.com)
- The key to medical education – teaching students and residents how to think (medrants.com)
- If it’s not Asthma, what is it? (lynnawiensmd.com)