What’s stiff-person syndrome, rare disorder that Celine Dion was diagnosed with?

Global music superstar Celine Dion said she was recently diagnosed with a rare neurological disorder -- stiff-person syndrome. In an emotional video messages posted in French and English on Thursday on Instagram, Dion said stiff person syndrome was causing spasms that affect her ability to walk and sing. “Unfortunately, the spasms affect every aspect of my daily life, sometimes causing difficulties when I walk and not allowing me to use my vocal cords to sing the way I’m used to,” she said.