The National MS Society is launching a five-year campaign to raise $1 billion to fund research and expand access to care.
"It burst my heart open," Blair said after her Viennese waltz brought the ballroom to tears.
Selma Blair is challenging herself by competing on "Dancing with the Stars." Her pro partner says her multiple sclerosis diagnosis makes things difficult, but she's persevering and inspiring others.
"May we find that strength to lift our heads up. Mine currently is on my pillow. But I try," she wrote.
"It's been a tough road. But as we all know, the road keeps going," the 49-year-old actress said.
An estimated 3.2 million Americans are living with spondylitis. That's more than Lou Gehrig's disease, multiple sclerosis, and rheumatic arthritis combined -- but still so few people know about it.