The second thing you learn in medical school (right after “the patient is the one with the disease”) is Occam’s Razor: the simplest explanation is the best one. If the patient has five symptoms, give him one disease that explains all five, not five unrelated problems.
What they don’t teach you, at least not right away, is Hickam’s Dictum: the patient can have as many diseases as he damn well pleases. I always thought this was the product of a straight-talking New Yorker, probably a Brooklynite, some larger than life Sir Lancelot Spratt who didn’t mince words and ate interns for lunch. But no, the internet tells me that John B. Hickam was a real person, chair of medicine at Indiana.
Anyway, I was thinking about old Dr. Hickam today, because I had a referral who had essential tremor, generalized dystonia, myoclonus, parkinsonism, two symmetric ditzels where his nigra ought to be AND a hummingbird sign. He was like a grab bag of movement disorders! I had two different attendings see him with me (and they both agreed with me that the primary problem was X but couldn’t explain problems Y, Z, and Q). Ended up videotaping him for future reference, but geez Louise! Why don’t patients read the textbooks??