Céline Dion was diagnosed with stiff-person syndrome. Here's how it affects people

The singer Céline Dion announced she finally has a diagnosis for the medical condition that has caused her to cancel and postpone performances over the past year.

In a tearful social media post Wednesday, the "My Heart Will Go On" singer said she's been suffering from stiff-person syndrome, a rare and incurable neurological condition that causes severe muscle spasms and stiffening in the limbs.

"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," Dion said in an emotional video posted on Instagram, which she published in both English and her native French.

Dion, 54, has repeatedly postponed and canceled performances in the past year because of health concerns, which she previously had described as "severe and persistent muscle spasms."

Dion was in the middle of a long concert tour in 2020 when it was interrupted by the pandemic. It was finally set to restart in February, with another 50 shows planned, but eight have been canceled and 23 have been rescheduled for 2024.

"All I know is singing," Dion said, growing emotional. "It's what I've done all my life and it's what I love to do the most."

The National Institute of Neurological Disorders and Stroke, a division of the National Institutes of Health, defines stiff-person syndrome as a neurological disorder with features of an autoimmune disease.

The disorder causes "fluctuating muscle rigidity" and spasms that are triggered by things like loud noise, cold temperatures or sudden movement. The spasms can cause or exacerbate falls, which can result in further injury.

"Abnormal postures, often hunched over and stiffened, are characteristic of the disorder. People with SPS can be too disabled to walk or move, or they are afraid to leave the house because street noises, such as the sound of a horn, can trigger spasms and falls," the institute says.

Stiff-person syndrome is rare. It affects "only about one or two in a million people," according to the Johns Hopkins School of Medicine.

Researchers don't fully understand the causes of the disorder, the NIH says, but it could be the result of an autoimmune disorder in the brain and spinal cord. People with SPS have elevated levels of antibodies that target an enzyme that synthesizes an important neurotransmitter in the brain.

The disorder is not curable, but treatment with muscle relaxants and anti-convulsants can help improve and control symptoms, doctors say.

In her announcement, Dion said she's drawing strength from her three children and believes she's on the road to recovery.

"I'm working hard with my sports medicine therapist every day to build back my strength and my ability to perform every day," she said. "But I have to admit it's been a struggle."

Dion is one of the most successful vocalists of all time. She has sold more than 200 million records worldwide and has had multiple singles reach No. 1 on Billboard charts, including "My Heart Will Go On," "The Power Of Love" and "It's All Coming Back To Me Now." Her years-long residencies in Las Vegas have been among the most profitable of all time.

The singer was set to begin a new residency at Resorts World Las Vegas sometime in 2023. It's not clear when that residency — which also has been postponed repeatedly since 2021 — will begin. She also will make her acting debut in May, when "Love Again," a romantic comedy with Priyanka Chopra, is scheduled for release.

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