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  • Singer Celine Dion revealed this week that she has been diagnosed with a neurological disorder called stiff-person syndrome.
  • SPS is an extremely rare progressive neurological disorder that affects the brain and spinal cord.
  • Symptoms of SPS may include stiff muscles in the torso, arms, and legs, says NINDS. People with SPS may also have greater sensitivity to noise, touch, and emotional distress.

Celine Dion has revealed that she has been diagnosed with stiff-person syndrome (SPS), a rare neurological disorder that causes muscle stiffness and painful muscle spasms.

“While we’re still learning about this rare condition, we now know this is what’s been causing all of the spasms I’ve been having,” the French Canadian singer, 54, told her Instagram followers in an emotional video Thursday.

“Unfortunately, these spasms affect every aspect of my daily life, sometimes causing difficulties when I walk and not allowing me to use my vocal chords to sing the way I’m used to,” she said.

As a result of her condition, Dion is postponing several tour dates in Europe.

SPS is an extremely rare progressive neurological disorder that affects the brain and spinal cord, according to the National Institute of Neurological Disorders and Stroke (NINDS).

It occurs in an estimated 1 in a million people, with the condition twice as common in women than in men.

“It’s quite rare. During their career, many neurologists will not have seen more than one or two patients with a diagnosis of stiff-person syndrome,” said Dr. Stacey Clardy, a neurologist at University of Utah Health in Salt Lake City, who specializes in autoimmune neurology.

“At the Autoimmune Neurology clinic at the University of Utah, we longitudinally care for over 50 patients with stiff-person syndrome,” she said. “And we’re a large, dedicated national referral center — so hopefully that gives perspective on the relative rarity of this condition.”

Symptoms of SPS may include stiff muscles in the torso, arms and legs, says NINDS. People with SPS may also have greater sensitivity to noise, touch and emotional distress.

“Changes in temperature (extreme cold or heat) can trigger [muscle spasms in] some patients, as well as large crowds, emotional stress, and generally any setting where there is a lot of simultaneous sensory input,” said Clardy.

People with SPS may eventually develop abnormal, hunched-over postures, or be too disabled to walk or move, the institute says.

In addition, falling is common because the condition can affect people’s ability to catch themselves. Serious injuries can result from these falls.

People with SPS may also avoid leaving the house because loud noises or stress can trigger spasms, leading to a fall.

For most people, SPS is a slowly progressive disease.

“As with any medical condition, the severity of symptoms fall along a spectrum — some people have very mild symptoms, others have quite severe symptoms,” said Clardy. “But in general, for most SPS patients, symptoms slowly progress over time.”

The cause of SPS not yet known but it is thought to be an autoimmune disorder. It is associated with more common systemic autoimmune conditions.

“It often occurs in an individual who has inherited a predisposition to certain types of more common systemic autoimmune conditions, such as type 1 (insulin-dependent) diabetes, autoimmune thyroiditis, pernicious anemia and Addison’s disease,” said Clardy.

“It very rarely would occur in someone who doesn’t have some sort of family or personal history of systemic autoimmune conditions,” she said.

“And even then, most people with a history of these more common autoimmune conditions will never have a family member who is diagnosed with stiff person syndrome,” she added.

Diagnosis of SPS can be made with a blood test that measures the levels of glutamic acid decarboxylase (GAD) antibodies. Most people with SPS have higher levels of GAD antibodies.

However, it may take some time before people receive an accurate diagnosis.

Because SPS is so rare, people with this condition may visit several doctors before seeing a neurologist who specializes in stiff-person syndrome.

Since there are more common causes of muscle spasms and cramps, people may have been, appropriately, treated with muscle relaxant or pain medications, said Clardy.

“This makes achieving the diagnosis even more challenging, ultimately, because the muscle relaxants or painkillers can interfere with our ability to diagnose SPS,” she said.

Another challenging aspect of diagnosis is the episodic nature of the symptoms.

“You can have a person with stiff-person syndrome in the exam room, and if they’re early in their condition, and having a good day, they can appear essentially normal at that one point in time when you are examining them,” said Clardy.

“But after they leave the clinic, they can have a very severe unprovoked muscle spasm,” she said.

In addition, existing systemic biases in medical practice related to gender may lead to delays in SPS diagnosis, she added, in particular for women.

Clardy said treatment for SPS involves a two-pronged approach, with treatments targeting symptom management, and treatments targeting the immune system.

“Symptomatic treatments lessen the muscle cramps and spasms. For that, we generally give a benzodiazepine such as diazepam (trade name Valium),” she said.

“The other half of our treatment approach involves dampening down the immune system attack on the body. That’s where IVIg [intravenous immune globulin therapy] falls. We also use some other immunosupressive medications off-label,” she said.

Dr. Marinos Dalakas, a neuromuscular medicine specialist at Thomas Jefferson University in Philadelphia, ran the clinical trial that initially showed that high-dose IVIg significantly improved stiffness, spasms, and gait over a three-month period in people with SPS.

Longer-term results from that trial were published this year in the journal Neurology Neuroimmunology & Neuroinflammation.

Dalakas told Clardy on a podcast of the American Academy of Neurology that his recent study showed that IVIg is beneficial for patients with SPS over the long term. The average follow-up period in the study was 3.3 years.

“We found that 67% of the patients improved,” he said. “The improvement was related to improved gait, better balance, reduced spasms and stiffness, reduced startle response and better ability to walk and appear in public spaces.”

However, for about 30% of people who initially responded to IVIG, the benefits diminished over time.

“This [diminishment] is related to disease progression,” he said, “and highlights the need [for] better therapies [and] more effective therapies over the long term.”

Clardy said more awareness of this disease is needed in the medical community, as are large, high-quality multicenter clinical trials. These trials will require additional funding.

“Those of us in autoimmune neurology who treat patients have been trying — and will continue trying — to attract funding agencies to work with us to study SPS,” she said.