When I was a kid, it occurred to me one day that my dad started using a cane to help me balance while I was walking. I can’t remember exactly when it showed up at our home on Chicago’s South Side—I was four or five years old, and suddenly, there it was, a smooth black wood cane, slender and strong. It was an early result of multiple sclerosis, which left my dad with a severe limp in his left leg. Slowly and silently, it erodes his central nervous system and weakens the strength of his legs. The disease had likely been taking its toll on Dad long before his diagnosis,…