Celine Dion has been diagnosed with a rare neurological condition called stiff person syndrome. This is an autoimmune disease that causes muscle spasms and extreme tightness, and there is no cure for it. The condition affects every aspect of her daily life, sometimes causing difficulties when she walks and not allowing her to use her vocal cords to sing the way shes used to. Dion has been undergoing daily physical therapy, but she is still in a lot of pain. The syndrome can also cause anxiety. Dions openness about her diagnosis has raised awareness for a disorder that is underdiagnosed.