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.
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.
There are several different subtypes or classifications for SPS, including:
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:
Stiff person syndrome is very rare. About 1 out of every 1 million people have the syndrome.
The two main symptoms of stiff person syndrome are:
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.
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.
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:
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.
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.
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:
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:
Your healthcare team may include several specialists, such as:
Medications that can help decrease stiffness, rigidity and painful muscle spasms include:
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.
There’s currently no cure for stiff person syndrome. Treatment involves managing symptoms.
As SPS is an autoimmune-related condition, there’s nothing you can do to prevent developing it.
Stiff person syndrome is a chronic (lifelong) condition. The prognosis (outlook) varies from person to person based on a few factors, including:
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.
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.
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.
If you have stiff person syndrome, it may help to ask your healthcare provider the following questions:
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.
Last reviewed by a Cleveland Clinic medical professional on 12/13/2022.
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