After eagerly poring through Zebra Cards countless times,
readers will, I hope,
gain an appreciation of what makes a good card (and what does not). To minimize
the amount of frustration and nonproductive effort, however, some general
principles are listed below:
- A rare disease does not a Zebra Card make. We seek little known,
but striking manifestations of any disorder, be it rare or common.
Thus, Mollaret meningitis is a rare condition, but it has no symptom
or sign sufficiently striking to set it off from other chronic meningitides.
The manifestation must be reasonably obscure;
every medical student knows that "sterile pyuria" occurs in renal tuberculosis,
even though renal tuberculosis is nowadays rare.
- Manifestations with long differentials should, in general, be avoided.
Thus, nephrotic syndrome after an insect sting is unsuitable because listing
"nephrotic syndrome" as the observation calls an extremely long differential
to mind. This can sometimes be circumvented by mentioning a specific population
in the zebra, for example, "nephrotic syndrome in a neophyte beekeeper" (ugh!).
When many of the items in the differential have occurred only at the case report
level of frequency, an approach similar to card EA-006 (calcified pinna) may be adopted.
- It is imperative that each zebra be referenced as completely as possible.
- No pediatrics, please (all those congenital syndromes!), unless untreated
or undiagnosed patients have been reported to live past adolescence. As
mentioned elsewhere, neurology is a zebra-rich environment, so submissions
in this category will be judged more stringently.
Finally: It was stated at the Outset, that this system would not be here, and
at once perfected. You cannot but plainly see that I have kept my word. But
I now leave my [classification] System standing thus unfinished, even as the
great Cathedral of Cologne was left, with the crane still standing upon the
top of the uncompleted tower. For small erections may be finished by their
first architects; grand ones, true ones, ever leave the copestone to posterity.
God keep me from ever completing anything. This whole book is a draught -- nay,
but the draught of a draught. Oh Time, Strength, Cash, and Patience!
Herman Melville, Moby-Dick