Stiff-Person Syndrome

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What is stiff-person syndrome?

Stiff-person syndrome (SPS) is a rare, progressive neurological disorder. Symptoms may include:

  • Stiff muscles in the trunk (torso), arms, and legs
  • Greater sensitivity to noise, touch, and emotional distress, which can set off muscle spasms  

Over time people with SPS may develop hunched over postures. Some people may be too disabled to walk or move. Many fall frequently because they do not have the normal reflexes to catch themselves. This can lead to serious injuries. People with SPS may be afraid to leave the house because street noises, such as the sound of a car horn, can trigger spasms and falls.  

Who is more likely to get stiff-person syndrome?

  • SPS affects twice as many females as males.
  • It is frequently associated with other autoimmune diseases such as type-I diabetes, thyroiditis, vitiligo, and pernicious anemia.
  • Scientists don't yet understand what causes SPS, but research indicates that it is the result of an autoimmune response gone awry in the brain and spinal cord.

How is stiff-person syndrome diagnosed and treated?

Diagnosing SPS

SPS is often misdiagnosed as Parkinson's disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia. A definitive diagnosis can be made with a blood test that measures the level of glutamic acid decarboxylase (GAD) antibodies.

Most people with SPS have elevated (higher) levels of GAD antibodies. Antibody titers are important for the diagnosis of SPS. A titer is a laboratory test that measures the presence and amount of antibodies in blood. Elevated GAD titers, up to 10 times above normal, also are seen in diabetes but in SPS the titers are very high (at least 10 times above the range seen in diabetes) or are present in the spinal fluid.

Treating SPS

With appropriate treatment, SPS symptoms may be kept under control. Several symptoms improve with oral diazepam (an anti-anxiety and muscle relaxant drug) or with drugs that alleviate muscle spasms, such as baclofen or gabapentin.

A study funded by the National Institute of Neurological Disorders and Stroke (NINDS) showed that intravenous immunoglobulin (IVIg) treatment is effective in reducing stiffness, sensitivity to noise, touch, and stress and for improving gait and balance for people with SPS. IVIg contains immunoglobulins (natural antibodies produced by the immune system) derived from thousands of healthy donors.

How can I or my loved one help improve care for people with stiff-person syndrome?

Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

Consider participating in a clinical trial so clinicians and scientists can learn more about SPS and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with SPS at

Where can I find more information about stiff-person syndrome?

The following organization may have resources that can help:

Genetic and Rare Diseases (GARD)

 Learn about related topics

Order publications from the NINDS Catalog
The NINDS Publication Catalog offers printed materials on neurological disorders for patients, health professionals, and the general public. All materials are free of charge, and a downloadable PDF version is also available for most publications.