Canada s singer Celine Dion (File Photo: AFP)
In a five-minute video posted on Instagram in French and English, a clearly emotional Dion said she had been dealing with the health problems "for a long time."
"Recently I have been diagnosed with a very rare neurological disorder called Stiff-Person Syndrome which affects something like one in a million people," the Canadian hitmaker said.
It has been causing spasms that "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.
"It hurts me to tell you today this means I won't be ready to restart my tour in Europe in February."
Dion, who is 54, said she was supported by her children and a team of doctors working every day to improve her condition, but added: "I have to admit, it's been a struggle."
Dion rose from small-town Quebec to worldwide fame in the 1990s with hits such as "My Heart Will Go On" -- the theme to James Cameron's Oscar-winning film "Titanic" -- and "The Power of Love", and has continued to sell out huge stadiums around the world.
That success was parlayed into a regular gig at Caesar's Palace in Las Vegas, where she had multiple long residencies.
She first mentioned the spasms when she delayed her European tour earlier this year.
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 US 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'
"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.