What is stiff-person syndrome?
Stiff-person syndrome (SPS) is a rare neurological disorder. Symptoms may include:
- Stiff muscles in the torso, arms, and legs
- Greater sensitivity to noise, touch, and emotional distress, which can set off muscle spasms
Scientists believe SPS can range from just one area of a person’s body to a widespread syndrome that affects multiple parts of the body and involves the brain, brainstem, and spinal cord. SPS is progressive, meaning it gets worse over time.
A person’s immune system is very important in keeping them healthy. It consists of cells, tissues, and organs that work together to help fight infections and other diseases. SPS is thought to be an autoimmune condition, which happens when your immune system attacks the healthy cells of your body by mistake.
Over time, people with SPS may develop hunched postures. Some people may be too disabled to walk or move. They may fall and hurt themselves because their reflexes and muscles don’t work like they should. 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.
One type of SPS is known as paraneoplastic syndrome. Paraneoplastic syndrome happens when a person’s immune system has a reaction to a cancerous tumor. Scientists think this type of SPS happens when cancer-fighting cells (known as T cells) mistakenly attack normal cells in the nervous system. Symptoms such as difficulty walking or swallowing, loss of muscle tone, slurred speech, and memory loss may start before a doctor finds a tumor, or cancer-filled growth. In many patients, the immune response can cause nervous system damage that is worse than the damage done to the tumor.
There are several types of paraneoplastic syndromes, including Lambert-Eaton myasthenic syndrome, encephalomyelitis, and myasthenia gravis.
Who is more likely to get stiff-person syndrome?
SPS affects twice as many women as men. Most people develop symptoms between the ages of 20 and 60, most often in their thirties and forties. Only 5% of cases of SPS have been found in children. SPS is often associated with other autoimmune diseases, such as type 1 diabetes, thyroiditis, vitiligo, and pernicious anemia.
How is stiff-person syndrome diagnosed and treated?
Diagnosing SPS
- A doctor will usually diagnose SPS through a neurological exam alongside additional tests and procedures. Because it is rare and little understood, SPS is often misdiagnosed as Parkinson's disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia.
- A concrete diagnosis can be made with a blood test that measures the level of certain antibodies. Most people with SPS have higher levels of glutamic acid decarboxylase (GAD) antibodies and anti-amphiphysin 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, are also seen in diabetes. SPS can be distinguished by much higher GAD titers than even diabetes, and through GAD titer presence in the spinal fluid.
- A doctor may also do an electromyography test to diagnose SPS. An MRI (magnetic resonance imaging) of the brain and spinal cord may be done to rule out other causes of rigidity and stiffness.
Treating SPS
With the right treatment, SPS symptoms may be kept under control. Several symptoms improve with benzodiazepines, such as diazepam (an anti-anxiety and muscle relaxant drug). Symptoms can also improve with other medicines that relax muscles or alleviate muscle spasms, such as baclofen, gabapentin, dantrolene, and tizanidine.
For people with SPS cases that are part of paraneoplastic syndromes, treatment usually focuses on taking care of any tumor or cancer that is found in the body, followed by steps to decrease the body’s autoimmune response. The stage of cancer when a person is diagnosed often determines the outcome of recovery. Plasmapheresis, a process that cleanses antibodies from the blood, may ease symptoms in some people with paraneoplastic disorders.
People with SPS may benefit from speech and physical therapy to help them adapt to changes and maintain function.
What are the latest updates on SPS?
The National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health (NIH), is the leading federal funder of research on the brain and nervous system. NINDS supports new and innovative research to better understand, diagnose, and treat autoimmune conditions such as SPS.
A study funded by NINDS showed that intravenous immunoglobulin (IVIg) treatment is effective in reducing stiffness and sensitivity to noise, touch, and stress in people with SPS. It also works to improve gait and balance for people with SPS. IVIg contains immunoglobulins (natural antibodies produced by the immune system) that come from thousands of healthy donors.
Scientists supported by NINDS are exploring genetic variations that might contribute to the autoimmune response in paraneoplastic syndromes (including SPS), in order to develop better, more targeted treatments. They are also studying related disorders that affect how the nerves communicate with muscles. This will help them understand changes in the body over time, and how they can build better diagnosis and treatment options for people affected by these disorders.
For more information on research about SPS, check NIH RePORTER, a searchable database of current and past research projects funded by NIH and other federal agencies. RePORTER also has links to publications and resources from these projects.
How can I or my loved one help improve care for people with stiff-person syndrome?
Clinical trials increase our understanding of SPS and related disorders with the goal of improving how doctors treat them. Consider participating in a clinical trial so clinicians and scientists can learn more about SPS. Clinical research with human participants helps researchers learn more about a disorder and perhaps find better ways to detect, treat, or prevent disease safely.
All types of participants are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities. This helps make sure 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 Clinicaltrials.gov, a searchable database of current and past clinical studies and research results.
Where can I find more information about stiff-person syndrome?
Information is available from the following organizations:
Genetic and Rare Diseases (GARD)
888-205-2311
National Organization for Rare Diseases (Paraneoplastic Neurologic Syndromes)
National Organization for Rare Diseases (Stiff-Person Syndrome)
617-249-7300
Stiff-Person Syndrome Research Foundation
info@stiffperson.org