Part witchcraft, part common sense.
It’s one of my favourite things to do. Because you can FIX SOMETHING. With nothing but your bare hands.
You’ve diagnosed vertigo (as opposed to the other dizzies). You have a suspicion it’s BPPV- benign paroxysmal positional vertigo, usually because the dizzy person says “…and when I roll over in bed, doc, I just want to puke in my shoes.”
BPPV is an inner ear disorder caused by little stones (what? I have rocks in my head?) in the semicircular canals of the ear. The semicircular canals control the sense of balance, and send signals to the brain about the position of the head, and how fast it’s moving. The fluid in the semicircular canals gets moved around by head movement, and if you get it moving (for example, by going on one of the spinny rides at the amusement park) such that it keeps going when your head stops, you get some confusion between the signal from your eyes (all finished now, hurrah for solid ground) and the one from your ears (well, it feels like I’m still spinning actually) which manifests as the ground moving under your feet or worse yet, the technicolour yawn.
So you Dix-Hallpike: tell the person you are going to try to make them dizzy because it will help you figure out what’s going on. Then ask them to sit on the examining table such that when they are to lie down their head will go over the end. They are sitting, you are standing behind them with their head in your hands. You have them turn their head to one side. Then you lie them down quickly with their head still turned to the side, and they end with their head turned, hanging 45 degrees off the end of the table.
If they start to say “whoa, oh no….” or their eyes jerk back and forth or they puke on your shoes it’s a positive test. If not, sit them up and try the other side.
Then you can do the Epley Maneuver: a series of turns which serve to reposition the little stones, known as otoliths, into an area of the inner ear where they don’t cause trouble. Essentially, what you do is get them to roll from the affected side to the unaffected side and sit up, holding each position long enough to allow the stones to settle. If the patient then manages to keep his or her head upright for the next 48 hours, they often find that this “cures” the vertigo. The cure may not be permanent- the stones are still present- but often a person will have several months of relief.
Several months of relief from five minutes of handwaving. A pretty good return on investment, IMHO.