Stiff Person Syndrome Is Not What You Think It Is

It sounds like something most of us have experienced at one time or another, particularly as we age. But stiff person syndrome is among the rarest of diseases, affecting fewer than 5,000 people in the United States. 

People with stiff person syndrome are stiff, but it’s nothing like how you feel after extended time on the couch or a night with a bad mattress. People who have stiff person syndrome experience alternating rigidity and spasm in their muscles. Muscles can be so rigid that they feel like a board. And the muscle spasms, which are extremely painful and can be triggered by stress or other external factors, can create enough force to break bones. 

"The condition tends to worsen insidiously and have a profound impact on ease of movement, causing an awkward and uncomfortable gait,” says Columbia University neurologist Claire Riley, MD. “Particularly when it is not recognized, stiff person syndrome can be severe and life-altering or even life-threatening."

Stiff person syndrome is often misdiagnosed or overlooked until the symptoms are severe and the person’s gait is very impaired. Riley spoke with us about the disease, what causes it, and how it’s treated.

What causes stiff person syndrome?

The cause of stiff person syndrome is unknown, but scientists and doctors think that the syndrome may be an autoimmune disease, a type of disease that happens when the immune system mistakenly senses something in the body is a foreign, harmful substance and attacks it. In stiff person syndrome, it’s thought that antibodies of the immune system attack an enzyme (GAD) in the brain and central nervous system. That attack leads to a change in signals sent from the brain to the muscles, causing muscles to stiffen and spasm.

How does stiff person syndrome compare to other stiffness?

Stiff person syndrome is a degenerative condition. It is not a temporary stiffness caused by being in one position for a long time. It is not relieved by usual body stiffness interventions, like stretching and muscle relaxers.

Other medical conditions, like multiple sclerosis, can cause stiffness, but each condition has its own characteristics. When someone has stiffness in multiple sclerosis there is also significant weakness. When someone has stiffness and rigidity (sustained muscle contraction) after a stroke, it is more focal rather than distributed throughout the body. The body’s immune response to cancer can make the body stiff. Type 1 diabetes can make the body stiff.

Who gets stiff person syndrome?

Stiff person syndrome affects twice as many women as men. We still do not know why. Autoimmune diseases in general are more common in women than men.

Stiff person syndrome is typically diagnosed in people:

• between ages 30 to 50
• who have other autoimmune diseases, specifically others involving GAD65 antibodies, most commonly diabetes
• who are women or were assigned female at birth

It is possible people who have less severe manifestations of stiff person syndrome have been overlooked or possibly misdiagnosed with muscle tension. As more doctors learn to screen people, especially people sent to orthopedic clinics, more people will get the help they need for the long term.

How do I know if I have stiff person syndrome?

Stiff person syndrome can be suggested by findings on electromyography testing (EMG). EMGs assess muscles and the nerves that control them. There are also blood and spinal fluid tests to find GAD antibodies typically found in the disease.

Symptoms of Stiff Person Syndrome

• Extreme muscle stiffness and rigidity
  • Most often in the head, neck, back, chest, and limbs
  • Less often, but severe, in the leg
• Extreme spasms
  • Triggered by stress, loud noises, and other environmental stimuli
  • So severe the person can fall down in response
• Difficulty walking
• Anxiety and/or depression

Can stiff person syndrome be cured?

Not yet. Currently, the effects of immunotherapy on neurological syndromes associated with GAD antibodies are incomplete.

How do you treat stiff person syndrome?

The best way to treat stiff person syndrome is to address both the underlying immunologic problem and the symptoms themselves: Remove or reduce production of the antibodies and simultaneously treat symptoms with high doses of sedatives or muscle relaxers for stiffness, for example. But note these medications are not prescribed to reduce stress and promote relaxation. The medications are prescribed to control muscle spasms and disruptive motor symptoms.

You do not need to control symptoms to give immunotherapies, but you want to address both issues—the symptoms that distress patients and interrupt their lives as well as the underlying neurologic problems.

Stiff person syndrome can be quite resistant to treatment so it can take a long time to feel relief.  We see success in taking a combination approach to immunotherapy: combining steroids with things like intravenous immunoglobulin IVIG; broad spectrum immune modulators; B cell directed agents that reduce the levels of that antibody producing cells.

Patients are usually treated by neuroimmunologists—neurologists who specialize in disorders of the brain and central nervous system that are caused or impacted by the immune system. Other such conditions include multiple sclerosis, which involves an autoimmune attack on the nerves’ protective coating, and infections of the nervous system.