What is stiff-person syndrome and what causes it?
Stiff-person syndrome is a rare, progressive movement disorder characterized by muscle stiffness and cramps in the torso and limbs. It is thought to be an autoimmune disease, resulting from a person’s immune system mistakenly attacking the nerve cells that produce chemicals in our body that help control muscle movements.
Who is most at risk?
Stiff-person syndrome most often occurs in people between 30 and 60 years of age, and it is slightly more common in women than men. It is sometimes associated with diabetes and, less frequently, breast cancer.
What are the signs and symptoms of stiff-person syndrome?
The condition presents with muscle stiffness and spasms in the limbs and/or torso, and can come on slowly or be rapidly progressive. It can affect one or more areas of the body or become widespread. The symptoms can be aggravated by various stimuli, including noise or physical activity, and usually fluctuate, with exacerbations that can last hours to days.
How is it diagnosed?
The diagnosis is based on the symptoms, a clinical examination showing muscle stiffness, and results of electromyography (EMG) studies that measure the electrical activity of the muscles. In stiff-person syndrome, the EMG will show continuous activity in opposing muscles, explaining the stiffness or inability to relax the muscles. Blood tests can also show the presence of autoantibodies, most frequently to glutamic acid decarboxylase (GAD), a protein that your immune system uses to attack foreign objects. These are not specific to stiff-person syndrome, though, as they are also sometimes present in people with diabetes who don’t have any neurological complications.
Can stiff-person syndrome be misdiagnosed or mistaken for other movement disorders?
There are many medical conditions that can cause stiffness, such as arthritis, Parkinsonism, or spasticity from stroke, but these have clinically distinct features, which can usually be recognized in routine examination. If you think you might have stiff-person syndrome, talk to your physician to determine if you should be tested.
How is this condition treated?
Stiff-person syndrome can be managed, but it can’t be cured. Treatments to improve mobility and comfort will be based on an individual’s symptoms, and can include muscle relaxants, anti-seizure medications, and immune therapies such as intravenous immunoglobulin (IVIg) or rituximab, to suppress the autoimmune reaction. Physical therapy can also be effective when coupled with medication.
What should someone expect if they are diagnosed?
The condition is variable, ranging from mild to severe, so it’s unpredictable. In some cases, the symptoms can be debilitating, requiring the use of a cane, walker or wheelchair. But in most cases the symptoms can be managed, and the person will be able to go on with their daily routines and maintain their quality of life.