Stiff Person Syndrome

Stiff person syndrome (SPS) is a rare chronic condition that causes muscle stiffness and painful muscle spasms. The severity of symptoms varies from person to person. There’s no cure for SPS, but treatment can help manage symptoms and slow the progression of the syndrome.


What is stiff person syndrome?

Stiff person syndrome (SPS) is a rare autoimmune neurological disorder.

People with this condition usually experience muscle stiffness in their trunk and abdomen (the middle part of their body). Over time, they also develop stiffness (rigidity) and spasms in their legs and other muscles. Walking may become difficult, and people become more prone to falls and injury.

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

Types of stiff person syndrome

There are several different subtypes or classifications for SPS, including:

  • Classic SPS: This is the most common form. It’s associated with GAD (glutamic acid decarboxylase) antibodies, though studies have reported other antibody associations.
  • SPS variants: There are several variants of SPS 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 SPS causing decreased consciousness, eye movement issues, ataxia and autonomic dysfunction. PERM commonly requires management in a hospital due to autonomic dysfunction.

Who does stiff person syndrome affect?

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

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

SPS is also associated with the presence of other autoimmune conditions, such as:

How common is stiff person syndrome?

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


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Symptoms and Causes

What are the symptoms of stiff person syndrome?

The two main symptoms of stiff person syndrome are:

  • Muscle stiffness or rigidity.
  • Painful muscle spasms.

SPS 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, your trunk (abdomen, chest and back) muscles are the first to become stiff. The rigidity causes pain and an aching discomfort. These symptoms can fluctuate 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 SPS. They can involve your entire body or only a specific area. These spasms can last a few seconds, minutes or, occasionally, a few hours.

Spasms can be triggered by:

  • 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, a condition in which your immune system attacks healthy cells for unknown reasons.

Many people with SPS make antibodies against glutamic acid decarboxylase (GAD). GAD plays a role in making 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 SPS. It’s important to note that the presence of GAD antibodies doesn’t mean that someone has SPS. In fact, a small portion of the general population has GAD antibodies without any adverse effects.

There are other antibodies associated with SPS, including glycine receptor, amphiphysin and DPPX (dipeptidyl peptidase-like protein 6) antibodies. There are also some people with SPS who have no detectable known antibodies. Research is ongoing to see if there are other potential antibodies that haven’t yet been discovered.


Diagnosis and Tests

How is stiff person syndrome diagnosed?

Stiff person syndrome can be difficult to, as since it’s rare and its symptoms are similar to other conditions such as ankylosing spondylitis, multiple sclerosis or other autoimmune conditions. A healthcare provider may use several tests to rule out these conditions and look for specific signs of stiff person syndrome.

They’ll ask you questions about your symptoms and perform a physical exam and neurological exam. If your provider suspects stiff person syndrome, tests to confirm the diagnosis may 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.

Management and Treatment

What is the treatment for stiff person syndrome?

Treatment for stiff person syndrome is based on your symptoms. The goal of treatment is to manage symptoms and improve your mobility and comfort.

The two main treatment strategies include:

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

Your healthcare team may include several specialists, such as:

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

Medications and therapies for symptoms

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

  • Benzodiazepines: Benzodiazepines are a class of drugs that treat a variety of conditions, such as anxiety, seizures and insomnia. They affect GABA signals. Healthcare providers often prescribe diazepam as a first-line treatment for SPS.
  • 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 SPS symptoms.

Therapies that may also help manage symptoms include:


There’s some evidence to suggest that intravenous immunoglobulin (IVIg) treatment (a type of immunotherapy) can improve symptoms for some people with SPS.

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 involves managing symptoms.



Can I prevent stiff person syndrome?

As SPS is an autoimmune-related condition, there’s nothing you can do to prevent developing it.

Outlook / Prognosis

What is 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 SPS 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 SPS worsens. Some people may need to use a cane, walker or wheelchair for assistance.

Living With

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 may 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 SPS 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, such as 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 my 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 healthcare provider.

What questions should I ask my doctor?

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?

A note from Cleveland Clinic

Understanding your stiff person syndrome (SPS) diagnosis can be overwhelming. Your healthcare team will devise a management plan that’s unique to you and your symptoms. It’s important to make sure you’re getting the support you need and to stay attentive to your health. Know that your healthcare team will be there to support you and your family.

Medically Reviewed

Last reviewed on 12/13/2022.

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