Stiff-Person Syndrome (SPS) causes muscle stiffness as well as spasms, normally between the ages of 30 to 60. The symptoms can remain stable in some cases, but get progressively worse in others.
According to the U.S. National Institutes of Health, it affects twice as many women as men.
If left untreated, SPS can potentially lead to difficulty walking and significantly impact a person's ability to perform routine daily tasks.
Although the exact cause of this syndrome is unknown, it is believed to be an autoimmune disease and sometimes occurs with other autoimmune diseases.
"All I know is singing, it's what I've done all my life and it's what I love to do the most," said Dion, breaking into tears.
"I miss seeing all of you, being on the stage, performing for you."
Her spring dates in Europe, which were due to begin in the Czech Republic in February, have been postponed to 2024, while eight of her summer shows have been cancelled entirely.
A number of performances between late August and October have not been changed.
The "Courage World Tour" began in 2019, and Dion had completed 52 shows before the Covid-19 pandemic put the remainder on hold.
She later cancelled the North American section of the tour due to her health problems.
It was to be the Grammy winner's first global concert tour in a decade and the first without her husband-manager Rene Angelil, who died from cancer in 2016.
The showbiz community voiced support for Dion on Instagram, with fellow singer Gwen Stefani, fashion designer Donatella Versace and actress Kate Hudson among tens of thousands leaving well wishes.
Dion sounded a note of optimism at the end of her video message.
"I have hope that I'm on the road to recovery. This is my focus," she said.
