Stiff Person Syndrome

What is stiff person syndrome?

Stiff person syndrome (SPS) is a rare autoimmune neurological disorder that causes muscle stiffness in your trunk and abdomen (the middle part of your body). Over time, you may also develop stiffness (rigidity) and spasms in your legs and other muscles. Walking may be difficult, and you may become more prone to falls and injury.

Understanding and managing your stiff person syndrome diagnosis can be overwhelming. Your healthcare team will create a treatment plan that’s unique to you and your symptoms, as they vary from person to person. It’s important to make sure you’re getting the support you need to stay healthy by scheduling regular visits with your providers throughout your life.

Stiff person syndrome used to be called “stiff man syndrome,” but the name was updated to be more inclusive, as the condition can affect people of any age and sex.

What are the symptoms of stiff person syndrome?

The two main symptoms of stiff person syndrome are:

• Muscle stiffness or rigidity.
• Painful muscle spasms.

Symptoms can develop at any age, but they most often begin in your 30s and 40s.

Stiff person syndrome symptoms can spread to other areas of your body and/or get worse over time. Symptoms can take several months to a few years to develop. Some people’s symptoms remain the same for years. Others experience slowly worsening symptoms, including more severe spasticity/rigidity, which can limit their ability to perform activities of daily living.

Muscle stiffness

In most cases of stiff person syndrome, the first symptom you’ll experience is muscle stiffness in your trunk (abdomen, chest and back muscles). The rigidity causes pain and an aching discomfort. These symptoms can fluctuate (swing) in severity without a clear reason or trigger. They can also affect your arms and legs. As stiffness increases, some people develop an abnormal posture that can make it difficult to walk or move.

Muscle spasms

Painful muscle spasms are another symptom of stiff person syndrome. They can involve your entire body or only a specific area. These spasms can last a few seconds, minutes or, occasionally, a few hours.

What triggers stiff person syndrome?

Symptoms of stiff person syndrome, like muscle spasms, can trigger (happen) after:

• Unexpected or loud noises.
• Physical touch or stimulation.
• Changes in temperature, including cold environments.
• Stressful events.

Due to the unpredictable triggers of muscle spasms, some people with SPS develop anxiety and agoraphobia — an extreme fear of entering open or crowded places or of leaving their homes. This is because it’s more difficult to avoid the triggers of muscle spasms out in public.

What causes stiff person syndrome?

Researchers don’t know the exact cause of stiff person syndrome. But they think it’s an autoimmune condition. This is a condition in which your immune system attacks healthy cells for unknown reasons.

Studies suggest antibodies may play a role in SPS. Many people with stiff person syndrome make antibodies against glutamic acid decarboxylase (GAD). GAD makes a neurotransmitter called gamma-aminobutyric acid (GABA), which helps control muscle movement.

Researchers don’t yet understand the exact role that GAD plays in the development and worsening of stiff person syndrome. It’s important to note that the presence of GAD antibodies doesn’t mean that you have stiff person syndrome. In fact, a small portion of the general population has GAD antibodies without any adverse effects.

There are other antibodies associated with stiff person syndrome, including glycine receptor, amphiphysin and DPPX (dipeptidyl peptidase-like protein 6) antibodies. There are also some people with this condition who have no detectable known antibodies. Research is ongoing to discover if other potential antibodies may also cause symptoms.

What are the risk factors for stiff person syndrome?

Women and people assigned female at birth (AFAB) are twice as likely to have stiff person syndrome as men and people assigned male at birth (AMAB).

Stiff person syndrome may also happen with other autoimmune conditions, like:

• Type 1 diabetes.
• Autoimmune thyroid disease.
• Vitiligo.
• Pernicious anemia.
• Celiac disease.

How common is stiff person syndrome?

Stiff person syndrome is very rare. About 1 out of every 1 million people have this condition.

How is stiff person syndrome diagnosed?

A healthcare provider will diagnose stiff person syndrome by looking for specific signs of the condition with exams and testing. They’ll ask you questions about your symptoms during a physical exam and neurological exam.

If your provider suspects stiff person syndrome, they may offer tests, which could include:

• Antibody blood test: A blood test can check for the presence of antibodies to GAD (or other relevant antibodies) and for other signs that might indicate or rule out other diseases.
• Electromyography (EMG): This test measures electrical activity in your muscles and can help rule out other causes of your symptoms.
• Lumbar puncture (spinal tap): During a lumbar puncture, a healthcare provider uses a needle to draw fluid from your spinal canal to check for the presence of antibodies to GAD. They’ll also look for other signs that might indicate or rule out other conditions.

Stiff person syndrome can be difficult to diagnose, as it’s rare and its symptoms are similar to other conditions, like ankylosing spondylitis, multiple sclerosis or other autoimmune conditions.

Types of stiff person syndrome

There are several different subtypes or classifications for stiff person syndrome, including:

• Classic stiff person syndrome: This is the most common form. It’s associated with GAD (glutamic acid decarboxylase) antibodies, though studies have reported other antibody associations.
• Stiff person syndrome variants: There are several variants of stiff person syndrome that can involve specific parts of your body or involve more prominent incoordination (ataxia).
• Progressive encephalomyelitis with rigidity and myoclonus (PERM): PERM is a more severe variant of stiff person syndrome, causing decreased consciousness, eye movement issues, ataxia and autonomic dysfunction. PERM commonly requires management in a hospital due to autonomic dysfunction.

How is stiff person syndrome treated?

The two main treatment strategies for stiff person syndrome include:

• Medications and therapies for symptom management.
• Immunotherapy, or disease-modifying treatment.

Treatment for stiff person syndrome varies based on your symptoms. Treatment aims to manage how symptoms affect you and improve your mobility and comfort.

Your healthcare team may include several specialists, including:

• Neurologists, specifically, neuroimmunologists.
• Occupational and physical therapists.
• Physical medicine and rehabilitation specialists.
• Speech therapists.
• Mental health specialists, like psychologists.

Medications and therapies for stiff person syndrome

Medications can help decrease stiffness, rigidity and painful muscle spasms, including:

• Benzodiazepines: Benzodiazepines are a class of drugs that treat a variety of conditions, like anxiety, seizures and insomnia. They affect GABA signals. Healthcare providers often prescribe diazepam as a first-line treatment for stiff person syndrome.
• Muscle relaxants: Baclofen can help treat muscle spasms. It works by relaxing your muscles, which reduces muscle stiffness.
• Neuropathic pain medications: Medications like gabapentin and pregabalin also affect GABA signals and can help with stiff person syndrome symptoms.

Therapies that may also help manage symptoms include:

• Physical therapy or occupational therapy.
• Massage.
• Hydrotherapy (water therapy).
• Heat therapy.
• Acupuncture.

Immunotherapy for stiff person syndrome

There’s some evidence to suggest that intravenous immunoglobulin (IVIg) treatment (a type of immunotherapy) can improve stiff person syndrome symptoms.

IVIg contains immunoglobulins (natural antibodies your immune system produces) donated by thousands of people with healthy immune systems.

Can stiff person syndrome be cured?

There’s currently no cure for stiff person syndrome. Treatment can help you manage symptoms.

Can stiff person syndrome be prevented?

As stiff person syndrome is an autoimmune-related condition, there isn’t anything you can do to prevent it.

What’s the prognosis for stiff person syndrome?

Stiff person syndrome is a chronic (lifelong) condition. The prognosis (outlook) varies from person to person based on a few factors, including:

• Symptom severity.
• How quickly the condition progresses.
• How well treatment helps.

Starting treatment soon after symptoms begin is essential to prevent or lessen the syndrome’s progression and avoid long-term complications. Most people with stiff person syndrome improve with medications, but it can still be difficult to manage triggers that cause muscle spasms.

Over time, walking can become more and more difficult. Your ability to perform daily routine tasks may also decline over time. The increased risk of falls also becomes a growing concern as the condition worsens. You may need to use a cane, walker or wheelchair for assistance.

How do I take care of myself if I have stiff person syndrome?

If possible, try to find a healthcare provider who specializes in researching and treating stiff person syndrome. Because the syndrome is rare, this could be difficult. You may have to advocate for yourself to ensure you get the best medical care that can help you have the best quality of life.

It’s common for people with stiff person syndrome to experience anxiety or depression related to the condition. If you’re experiencing mental health symptoms, it’s important to talk to your provider or a mental health specialist, like a therapist or psychologist.

You and your family may also want to consider joining a support group to meet others who can relate to your experiences.

When should I see a healthcare provider?

If you have stiff person syndrome, you’ll need to see your healthcare team regularly to check if your treatment is working and to monitor the progression of your symptoms.

If you notice new symptoms or side effects of your medications, talk to your provider.

What questions should I ask my healthcare provider?

If you have stiff person syndrome, it may help to ask your healthcare provider the following questions:

• What treatment do you recommend based on my symptoms?
• What can I do at home to help my symptoms?
• What signs of complications should I look out for?
• What can I expect to happen to my health in the future?
• Are there any clinical trials for stiff person syndrome?