What is Stiff-Person Syndrome? 

Shandra Martinez

| 3 min read

A young woman got severe cramps in her foot at night while sleeping.
Have you ever heard details of a rare illness and realized you really don’t know much about it – or what causes it? Stiff-person syndrome is one of those infrequent neurological disorders that most people don’t know too much about. As testing and treatment methods continue to evolve for this condition, research is revealing more details about the possible cause, the symptoms of stiff-person syndrome, and how it can be initially confused with other health issues.

What is SPS?

Stiff-person syndrome, or SPS, is a rare autoimmune neurological disorder that affects a person’s nervous system and impacts their range of motion and how their body moves. It can cause muscles in the back – or other areas of the body – to feel very stiff or difficult to move, according to the Mayo Clinic. In extreme cases, it can give people the appearance of a hunched back and put them at such risk of injury that they do not want to leave their home.

Symptoms of SPS

Like its name implies, this progressive disorder affects the muscles. Symptoms of stiff-person syndrome include:
  • Severe stiffness in the back, lower torso, arms or legs.
  • Spasms in muscles in those areas.
  • There can be an exaggerated startle response, which can lead to falls or injury.
  • Sensitivity to touch, too-loud sounds or stress, which can lead to muscle spasms.
  • Developing a hunched posture, which can also lead to falls or injury.
  • In extreme cases, a person may not want to be in public or walk through crowds, as loud noises can cause a physical reaction, causing an injury.

What causes SPS? 

While researchers have not yet been able to pinpoint a specific cause for SPS, they do know it’s an autoimmune response likely triggered by mixed signals between the brain and spinal cord, according to the National Institutes of Health.

Who is most likely to develop SPS?

Twice as many women than men are diagnosed with SPS, with the earliest diagnosis coming in a person’s 40s or 50s. Also of note is that SPS often is not a stand-alone autoimmune illness. People with this progressive disorder also often have another autoimmune health issue, like Type 1 diabetes, thyroid issues or vitiligo.

Diagnosing SPS

Because of how the symptoms of SPS present themselves, many people who are ultimately diagnosed with this disorder are often initially misdiagnosed with another muscle-related health issue, like multiple sclerosis, fibromyalgia or even Parkinson’s disease. Some people with SPS are mistakenly told they have a genetic back problem, or even that the pain and stiffness they’re experiencing is a psychiatric issue. But there is a definitive blood test that can be used to diagnose SPS. It can detect a specific antibody that signals the presence of the disorder. These antibodies are also present in a person’s spinal fluid, when tested.

Treating SPS

The good news is there is treatment available for SPS. This treatment can lessen the severity and frequency of the symptoms and help control them. Treatments include:
  • Anti-anxiety medication
  • Muscle-relaxing drugs
  • Medication to reduce muscle spasms
  • IV immunoglobulin treatments, which contain antibodies from healthy donors
If you or a loved one are experiencing any symptoms of SPS, talk to your health care provider about testing and treatment.
Photo credit: Getty Images

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