Celine Dion 'can't find any medicine that works' amid stiff-person syndrome battle

Celine Dion's sister says the 'My Heart Will Go On' singer is unable to "find any medicine that works" to help combat her stiff-person Syndrome.

In December last year, Dion postponed several European tour dates after she was diagnosed with the rare neurological disorder, which prevented her from singing the way she wanted to.

Sister Claudette told Le Journal de Montreal that Celine was being cared for by their sister and was "working closely" with researchers who specialised in the rare condition.

The condition reportedly affects just one person in every million.

"We can't find any medicine that works, but having hope is important," Claudette said.

"I honestly think that she mostly needs to rest. She always goes above and beyond, she always tries to be the best and top of her game.

"At one point, your heart and your body are trying to tell you something. It's important to listen to it."

Claudette also revealed they were optimistic they'd find a method of rehabilitation that worked for her.

"When I call [Celine] and she's busy, I speak to my sister Linda who lives with her and tells me that she's working hard."

Earlier this year Claudette appeared on TV in Quebec, saying they would fight on.

"We're all crossing our fingers, and I'm glad people are concerned. She is working hard, and we are confident that we will succeed. It can't be a story like this."

In December, Dion revealed the diagnosis in an emotional online post.

"While we're still learning about this rare condition, we now know this is what's been causing all of the spasms that I've been having," she said. 

"Unfortunately, these 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."