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Stiff-Person Syndrome: What is it and is it Common?

Recently, Celine Dion announced that she has been diagnosed with a neurological disorder called Stiff-person syndrome (SPS). The singer revealed that she would be stepping away from music and performing because the disorder doesn’t allow her to sing to her normal standards.

How common is SPS?

SPS is an extremely rare autoimmune neurological disorder. About one in a million people are diagnosed with SPS.

“It’s like a lightning strike occurring within a family with susceptibility to autoimmunity,” says Stacey Clardy, MD, PhD, an Autoimmune Neurologist and associate professor in the Department of Neurology in the Spencer Fox Eccles School of Medicine at University of Utah and the VA Salt Lake City Health Care System. Clardy established the Autoimmune Neurology Clinic at University of Utah Health—one of the only clinics of its kind in the world—which takes care of about 50 patients with SPS.

What are the signs and symptoms?

A person with SPS usually experiences muscle spasms or muscle stiffness anywhere in the body. Symptoms can range from mild to severe. Patients often have a heightened sensitivity to noise, crowds, and emotional distress. The spasms can happen randomly or be triggered by an event like sudden movement, unexpectedly loud sounds, changes in temperature, or stress.

“Have you ever woken up in the middle of the night with a charley horse in your calf?” Clardy says. “Imagine that pain, but all the time, longer lasting, and much more severe. You can’t rub the cramp out or otherwise get the muscle spasm to let up either.”

According to the National Institutes of Neurological Disorders and Stroke (NINDS), severe cases of SPS can make it hard for people to walk or move and cause them to have hunched postures. The condition is often slowly progressive, and the severity of symptoms, along with which muscles are affected, varies from person to person. 

Clardy emphasizes that just because a person has muscles spasms or cramps doesn’t mean they have SPS. There are many more common causes of muscle spasms and stiffness.

How is SPS diagnosed?

SPS is often misdiagnosed as Parkinson’s disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia, according to NINDS.

Patients who have SPS usually have a higher level of glutamic acid decarboxylase (GAD) antibodies, glycine receptor antibodies, or amphiphysin antibodies. Patients can be tested for these antibodies through a blood test and also a test of cerebrospinal fluid. Clardy says that a person with SPS usually has 10 to 100 times the normal number of GAD antibodies.

What causes SPS?

It’s not known what causes SPS. Some research has shown that there may be a genetic connection with other autoimmune conditions that are either present in the person diagnosed with SPS or in other family members.

“Most patients inherit a genetic susceptibility to much more common autoimmune conditions,” Clardy says. “But the patient with SPS in a family is usually the only person over many generations that gets this very rare form of neurologic autoimmunity.” 

According to the National Organization for Rare Disorders (NORD), the most common associated condition is insulin dependent diabetes, commonly referred to as Type 1 diabetes. The disorder can also be associated with other autoimmune diseases such as thyroiditis, vitiligo, and pernicious anemia.

Who does SPS affect?

SPS is more common in women than men. In fact, NINDS says SPS affects at least twice as many women, and they are usually diagnosed in middle age, or between 30-60 years old.

Are there treatment options?

Clardy says there is a two-pronged approach to treatment to help slow down progression of SPS. This includes: 

  1. Managing symptoms using muscle relaxants and similar medications to help with muscle spasms.
  2. Immune system modulation that suppresses or distracts the immune system from attacking the body. 

Treatment is based on individual assessments and severity of symptoms. Those concerned about potential symptoms of SPS should discuss their symptoms with their primary care physician or a neurology specialist to see if referral to University of Utah Health’s Autoimmune Neurology Clinic or another specialty clinic might be necessary.

More research is needed

There is still much more that needs to be learned about SPS. Clardy stresses the need for research to better understand the cause of SPS, the role of antibodies, and, importantly, the need for better treatments for those who currently have SPS.