Celine Dion's sister has shared an update while the "Heart Will Go On" singer deals with a rare health issue.

"She's doing everything to recover," Dion's older sister Claudette told Hello! Canada on Thursday. "She's a strong woman."

The Grammy-winner's family is rallying around her as she battles Stiff Person's Syndrome, a rare disorder that causes involuntary muscle spasms.

"It's an illness we know so little about," Claudette said. "There are spasms -- they're impossible to control.

She added that "there's little we can do to support her, to alleviate her pain."

Dion announced in December of last year that she had been diagnosed with the syndrome, and was taking time off from professional commitments to focus on her health.

And while she announced new music in April and appeared in a film opposite Priyanka Chopra, a source close to Dion told CNN in late May that she "will likely never tour again."

This week, Claudette said that "We're crossing our fingers that researchers will find a remedy for this awful illness."

The Canadian publication also said Dion has been based in Las Vegas where she's working with a team of doctors as well as a sports medicine therapist to regain her strength.