This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Stiff person syndrome (SPS) is a rare, progressive syndrome that affects the nervous system, specifically the brain and spinal cord. Symptoms may include extreme muscle stiffness, rigidity and painful spasms in the trunk and limbs, severely impairing mobility. Spasms can generate enough force to fracture bone. People with SPS often have heightened sensitivity to noise, sudden movements, and emotional distress, which can set off muscle spasms. Persistent symptoms can lead to abnormal posturing of the spine, such as being hunched over. The syndrome affects twice as many women as men.
SPS is caused by increased muscle activity due to decreased inhibition of the central nervous system. It is thought to have an autoimmune component and is often associated with diabetes, as well as other autoimmune diseases such as thyroiditis, vitiligo, and pernicious anemia. It may be diagnosed after having various tests including blood tests (such as for glutamic acid decarboxylase (GAD) antibodies which is elevated in about 2 in 3 people with SPS), a lumbar puncture, and electromyography. Treatment aims to control symptoms and improve mobility. Examples of treatments that have been used for SPS, include benzodiazepines, muscle relaxants, intravenous immune globulin (IVIG) therapy, plasmapheresis (also called plasma exchange), and rituximab. While some people with SPS may maintain reasonable levels of activity with treatment, the majority become disabled over time.
For more information, visit GARD.