On Being a Zebra (or why Occam’s razor doesn’t always work)

Among competing hypotheses, the one with the fewest assumptions should be selected.  (Occam’s razor)
“Whenever an affirmative proposition is apt to be verified for actually existing things, if two things, howsoever they are present according to arrangement and duration, cannot suffice for the verification of the proposition while another thing is lacking, then one must posit that other thing.” (Chatton’s “anti-razor”)
“Patients can have as many diseases as they damn well please.” (Harrum’s Dictum)

This is Zoe. She’s a rare “Golden Zebra.”

Medicine has its own little collection of aphorisms–pithy sayings that often get trotted out to try to explain or discount patient behavior. These aren’t limited to variations on Occam’s razor, but they often work to suggest that the simplest explanation is best. On more than one occasion, I have been subjected to a paraphrase of Dr. Theodore Woodward’s directive: “When you hear hoofbeats, think of horses not zebras.” This is generally taken to mean that the physician should consider the most common diagnosis first, rather than an exotic one.  I suppose this is good advice for the medical intern, or the harried ER doctor, but what happens when it is a zebra, and not a horse? Or two zebras? Or a herd full of zebras? Or an albino zebra?

All of this is on my mind today because I saw my rheumatologist earlier this morning to discuss my unsuccessful attempts at tapering off of prednisone. I had hoped Kineret would be my magic bullet– and it has been for my inflammatory arthritis (which meets the diagnostic criteria for RA, but is likely a variation of TRAPS and/or AOSD). However, as it turns out, lupus is still lurking in the shadows, and was all too happy to make an appearance once the prednisone shield came down. So back up the prednisone dosage goes.

At this point, I wish I were better at grappling with  uncertainty. If nothing else, chronic illness forces you to relinquish the illusion that having a diagnosis is an end point. It’s really just the beginning, and always subject to revision. As my doctor said today, my symptoms could be entirely different in five years. So I do my best to focus on now, and on what will allow me to have the best quality of life–to flourish–now. If it means prednisone today, it means prednisone today. Maybe later it will mean Imuran, CellCept, or Benlysta.  Maybe research into autoimmune and autoinflammatory diseases will reveal new causes and new treatments and I will end up with an entirely different diagnosis altogether.

It’s so easy to be discouraged, but then I think back to how miserable I felt when I was first diagnosed, then when I was on methotrexate and Arava with the added trauma of losing half my hair (and sometimes what felt like half my mind), and it’s easier to see how far I’ve come. A few milligrams of prednisone isn’t the end of the world. Diagnoses are a means to an end.  It doesn’t “please” me to have more than one rare disease, but if I’m a zebra, I’m a zebra. I didn’t choose to be the exotic one, but really, who would choose to be a horse when you could be a zebra instead?

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