“I pulled a calf muscle; then I noticed that I limped when I got tired running for a ball,” recalled Ms. Adan, a Brooklyn native who now lives in Chicago. “My balance was still fine, but then I pulled a muscle in the other leg. The limp kept getting worse, and I began to feel off-balance. When I closed my eyes, I felt like I would fall backward – I was afraid to take a shower and wash my hair – and I noticed that I couldn’t easily move my left leg.”