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Celine Dion has been diagnosed with a rare condition called stiff person syndrome.
CNN  — 

Complications from stiff person syndrome, a rare neurological condition that causes spasms and muscle rigidity, have caused singer Celine Dion to cancel her “Courage World Tour” dates through 2024, according to a statement posted Friday on the star’s social media account.

Dion postponed several performances in December after learning the reason for her muscle pain and difficulties with mobility. “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,” Dion said at the time.

Despite undergoing daily physical therapy, “she is in a lot of pain,” a source close to Dion told CNN.

In the Instagram announcement of the tour’s cancellation, Dion is quoted as saying: “I’m so sorry to disappoint all of you once again. I’m working really hard to build back my strength, but touring can be very difficult even when you’re 100%.

“It’s not fair to you to keep postponing the shows, and even though it breaks my heart, it’s best that we cancel everything now until I’m really ready to be back on stage again. I want you all to know, I’m not giving up… and I can’t wait to see you again!”

What is stiff person syndrome?

Stiff person syndrome is characterized by muscle rigidity and spasms, heightened sensitivity to stimuli such as sound and lights, and emotional distress that can cause muscle spasms, according to the National Institute of Neurological Disorders and Stroke. Over time people with the condition can develop “hunched over postures,” the NINDS said.

The condition typically begins with muscle stiffness in the middle part of the body, the trunk and abdomen, before advancing to stiffness and spasms in the legs and other muscles, according to the Cleveland Clinic.

The muscle spasms can be “quite severe. These can cause falls, severe pain and significant disability,” said Dr. Emile Sami Moukheiber of the Stiff Person Syndrome Center at Johns Hopkins Medicine. “Falls from severe spasms are very common. These spasms can be precipitated by startle, severe emotions, cold weather.”

These spasms can be strong enough to fracture bone, and any fall can lead to severe injury.

Dion said in her December Instagram video that spasms affect “every aspect” of her 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. It hurts me to tell you this today.”

The syndrome can also cause anxiety.

“Many patients, if not all, have an anxiety that is intrinsic to the disease and that anxiety actually feeds on the physical ailments of the disease that people can have,” Dr. Scott Newsome, director of the Stiff Person Syndrome Center, said in a video on the organization’s website.

At times, people with stiff person syndrome may be afraid to leave their homes because “street noises, such as the sound of a car horn, can trigger spasms and falls,” the NINDS noted.

Who is at risk of developing stiff person syndrome?

Stiff person syndrome is very rare. About 1 out of every 1 million people have the syndrome, and most general neurologists will see only one or two cases in their lifetimes, Moukheiber said.

The first case of stiff person syndrome was reported in the 1950s, according to Newsome, and the disease was historically referred to as “stiff man syndrome.”

Since then, it has been found to affect twice as many women as men, and the name was changed to stiff person syndrome to avoid confusion.

The condition can develop at any age, but symptoms most often begin in a person’s 30s or 40s, according to the Cleveland Clinic.

What causes stiff person syndrome?

Stiff person syndrome is thought to have features of an autoimmune disease, according to the National Institute of Neurological Disorders and Stroke: “It is frequently associated with other autoimmune diseases such as type-I diabetes, thyroiditis, vitiligo, and pernicious anemia.”

Although the exact cause isn’t clear, according to the institute, research shows it may be due to an autoimmune response “gone awry” in the brain and spinal cord.

“People with SPS have elevated levels of GAD, an antibody that works against an enzyme involved in the synthesis of an important neurotransmitter in the brain,” the institute noted on its website. “A definitive diagnosis can be made with a blood test that measures the level of glutamic acid decarboxylase (GAD) antibodies.”

Other tests include an electromyography (EMG), which measures electrical activity in the muscles, and a lumbar puncture, commonly called a spinal tap.

Because of the rarity of the disease and the ambiguity of its symptoms, people will often seek care for chronic pain before they get neurological care. The condition can be misdiagnosed as anxiety, fibromyalgia, multiple sclerosis, Parkinson’s disease, psychosomatic illness or even a phobia, the NINDS noted.

On average, it takes about seven years for someone to receive a diagnosis of stiff person syndrome, Newsome says.

“Sometimes, [patients] get labeled crazy,” he said, “because on exam early on, there aren’t the hallmark features of stiff person syndrome.”

How is stiff person syndrome treated?

There is no known cure for stiff person syndrome, but medications can ease the symptoms. Immunoglobulin medications can help lower sensitivity to light or sound triggers, potentially helping head off falls or spasms.

Pain relievers, anti-anxiety medications and muscle relaxers can be a part of treatment for this disease. The Stiff Person Syndrome Center also uses botulinum toxin injections.

Additional benefits may come from the use of acupuncture, physical therapy, heat and water therapy, the Cleveland Clinic noted.

“If left untreated, the disease can cause severe impairment of daily living,” Moukheiber said.

Dion, who previously said she has struggled with her health for a while, said she has a great team of medical professionals and her children’s support.

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

For a performer like Dion, loud noises and bright lights could act as triggers of muscle spasms.

“This is a very challenging illness that might take a toll on her if it is not treated aggressively, timely and appropriately,” Moukheiber said.