What Is Stiff Person Syndrome and Can You Still Have Sex?

Key Points

• Stiff person syndrome is very rare, the exact cause is unknown and there is no known cure.
• The primary symptoms of SPS are muscle stiffening and spasming, as well as problems with coordination, speech and vision.
• SPS is typically diagnosed by a combination of clinical symptoms and lab tests, including bloodwork to to test for specific antibodies.

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When Canadian singer Celine Dion, known as the "Queen of Power Ballads," revealed in December 2022 that she'd been diagnosed with stiff person syndrome, it brought widespread attention to a previously little-known autoimmune disease.

What is stiff person syndrome?

Stiff person syndrome (SPS) is a disorder that causes muscle spasms and rigidity. Among the rarest of all diseases, SPS impacts around 1 in 1 million people, according to a 2021 report.

However, the exact incidence of SPS is unknown, according to Amanda Piquet, M.D., the director of autoimmune neurology at the University of Colorado School of Medicine in Aurora, Colorado.

"We don't have large-scale epidemiology studies needed to know the true prevalence of the disease," she said. "It's a very rare disease that often goes unrecognized and misdiagnosed."

Stiff person syndrome is an autoimmune and neurological disorder that makes muscles in the torso and limbs alternate between rigidity and spasms. The severity of symptoms varies from person to person.

Researchers don't know the exact cause of stiff person syndrome. There is no known cure.

What are the symptoms of stiff person syndrome?

The primary symptoms of SPS are muscle stiffening and spasming, according to Kyle Blackburn, M.D., a neurologist at UT Southwestern Medical Center in Dallas. The rigidity and spasms are most prominent in the back, abdominal muscles and legs.

"People will describe trouble walking and will often struggle to bend their knees when they walk—a so-called 'Tin Man' gait," he said. "Sudden, uncontrolled muscle contractions called spasms are also common. These are often induced by startling sounds or events."

The episodic spasms can be extremely painful, explained James Weiss, M.D., a Pittsburgh-based advisory board chair member of the Stiff Person Syndrome Research Foundation.

"These terrible muscle spasms can last for hours and are completely debilitating," he said. "Spasms can be intense enough to induce falls and even trigger enough force to dislocate joints and break bones."

As well as alternating stiffness and spasms, people with SPS may experience problems with coordination, speech and vision, Blackburn added.

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What causes stiff person syndrome?

Scientists don't know the cause of stiff person syndrome. However, some researchers believe it may be the result of an autoimmune reaction, according to Blackburn.

"Stiff person syndrome is an autoimmune disease, where a misdirected immune response targets the nervous system," he said. "The prevailing thought is that specific cells in the brainstem and spinal cord that are responsible for muscle relaxation are being injured, causing the symptoms of the disorder."

Stiff person syndrome affects twice as many women as men.

"It often occurs in people who are predisposed to autoimmune diseases," Piquet said. "In addition to a genetic predisposition, SPS is likely caused by a combination of environmental triggers and a lot of bad luck."

How is stiff person syndrome diagnosed?

"Diagnosing SPS can be a challenge, and misdiagnosis is common," Piquet said. "There is no consensus on the criteria for diagnosis of the disorder, but doctors may rely on a combination of clinical symptoms and lab tests to diagnose SPS."

Neurologists will typically perform a thorough exam to identify symptoms and features consistent with the disorder, such as stiffness in the limb and axial muscles and painful muscle spasms, Blackburn explained.

The process of diagnosing SPS also includes bloodwork to test for certain antibodies.

"Most people with stiff person syndrome have really high levels of antibodies to glutamic acid decarboxylase, or GAD, a protein that is critical to synthesize neurotransmitters responsible for muscle relaxation in their blood and spinal fluid," he said.

The GAD antibody is present in up to 80 percent of SPS cases, and high levels of the antibody are strong indicators of the disease, a 2020 study suggested.

"Other tests commonly performed include a lumbar puncture, or spinal tap, to look for signs of inflammation, and tests of muscle and function," Blackburn said.

Is stiff person syndrome genetic?

"It doesn't appear to be genetic. Like many autoimmune disorders, there appear to be certain genes related to immune function that are more common in persons with stiff person syndrome," Blackburn said. "However, their role in the disease is not well understood, and they are probably just one of many factors that ultimately lead someone to develop the disease."

What are the first symptoms of stiff person syndrome?

The first symptoms of SPS may be different for different people. For some, the back, chest and stomach muscles are the first to stiffen.

"Over time, symptoms may grow worse or improve," Weiss said. "It progresses at variable rates in different people."

Can you still have sex with stiff person syndrome?

Most people who have stiff person syndrome may still be able to have sex.

"There isn't a lot of research into how SPS affects people's sexual behavior," Weiss said.

However, the condition may impact libido and compromise sexual desire.

"People with SPS are often in so much discomfort that it may inhibit their interest and ability to engage in sexual activity," he said. "They have these muscle spasms and cramps, and some people who are pretty far along in the disease may be bedridden."

The associated medications are another element that may impact sexual interest for people with SPS, Weiss explained.

Commonly prescribed benzodiazepines for stiff person syndrome, such as diazepam and clonazepam, have been linked to sexual problems such as decreased desire and difficulty achieving orgasm, a 2021 report suggested.

Can stiff person syndrome kill you?

It's unlikely that stiff person syndrome will kill you, Blackburn noted.

"Stiff person syndrome does not have a significant impact on lifespan in most cases," he said. "However, stiff person syndrome is a chronic disorder that can be disabling. There are rare, serious variants of the condition that can affect breathing and the body's ability to regulate blood pressure and heart rate that are potentially fatal."

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What is the life expectancy for someone with stiff person syndrome?

"Estimating the life expectancy of someone with SPS is tricky," Piquet said. "We don't have enough data on the natural history of the disease, so it's hard to make a blanket statement about life expectancy."

The disease is disabling but not necessarily deadly, she added. However, associated complications such as violent muscle spasms could lead to shortened life expectancy.

Is there a cure for stiff person syndrome?

"This is a disease that we do not have a cure for," Piquet said. "However, there are treatments we use to help in the management of the disease."

Treatment typically includes medications to address symptoms and therapies to target the underlying autoimmunity.

"Common symptomatic medications used for stiff person syndrome include diazepam, clonazepam and baclofen," Blackburn said. "These medications promote muscle relaxation and can help reduce spasms."

In addition to the therapies used to treat muscle spasms, doctors may prescribe immune therapies directed at the immune system, he added.

Scientists aren't sure how immune therapies work, according to Piquet. It's thought that immune therapies may help reduce the production of antibodies, but such therapies also help patients who are antibody-negative.

Is stiff person syndrome the same as scleroderma?

Scleroderma is a chronic autoimmune disorder that affects the connective tissue, according to the National Scleroderma Foundation. Although they are both chronic autoimmune diseases, SPS and scleroderma are different diseases.

"Stiff person syndrome is an autoimmune disorder that specifically targets the nervous system," Blackburn said. "Scleroderma tends to affect the skin and other organs and only rarely affects the nervous system."

The bottom line

"The diagnosis of SPS is a challenge and misdiagnosis is common," Piquet said. "It really requires a thorough neurologic evaluation by someone who is familiar with this disease."

The longer that stiff person syndrome goes undiagnosed and untreated, the more difficult it may be to get symptoms under control. If you or a loved one is experiencing symptoms associated with stiff person syndrome, consult with a medical professional who specializes in SPS or autoimmune disorders.

The good news? SPS is incredibly rare, and it's far more likely that any muscle rigidity or spasms are caused by stress, injury or extended sitting. Nevertheless, it's critical to detect SPS early to develop an effective treatment and symptom management plan, so don't hesitate to seek professional medical advice if you're concerned.