Stiff Person Syndrome

The main symptoms of SPS are progressive, fluctuating muscle rigidity and painful muscle spasms. Muscle spasms may occur spontaneously or be triggered by stimuli such as sudden noises, physical touch, temperature changes, or emotional distress. 

Most people start to experience symptoms between the ages of 30 and 60. The initial signs include muscle stiffness, aching discomfort, or pain, especially in the lower back and legs, which can lead to difficulty walking and performing daily activities. The severity and progression of symptoms can vary from person to person. In many cases, the symptoms slowly progress over several months or years.

People with SPS have a limited range of movement and impaired reflexes, so intense spasms can make them prone to falls and injuries. Individuals with more severe symptoms may develop a hunched, stiffened posture or require the use of a wheelchair. They are also more likely to experience anxiety and depression. Researchers have found that many people with SPS also have another autoimmune disease, such as type 1 diabetes, pernicious anemia, thyroiditis, or vitiligo. SPS also seems to be more common in people with certain types of cancer, including lymphomas, breast cancer, lung cancer, thyroid cancer, colon cancer, and kidney cancer.

Because SPS is rare and has numerous symptoms that overlap with those of other brain diseases, it is often misdiagnosed as multiple sclerosis, Parkinson’s disease, or fibromyalgia. Doctors may order an antibody blood test that measures a person’s level of GAD antibodies in order to get a more accurate diagnosis. In addition to an antibody test, doctors may use an electromyography (EMG) test to measure electrical activity in the muscles throughout the body. This can aid in diagnosis as well as help monitor a person’s response to treatment.

SPS is a chronic condition, and there is no known cure. Because symptoms can vary in their type and degree of severity, treatment plans require a personalized approach. Treatments focus on managing pain, relaxing muscles, and suppressing the overactive immune response responsible for SPS.

Doctors may prescribe a variety of medications to treat SPS symptoms, including pain relievers, muscle relaxants, anti-seizure and anti-anxiety drugs, sedatives, and steroids. Non-medication treatments may include stretching, heat therapy, water therapy, and massage and physical therapy. With appropriate treatment, symptoms can be well-managed.

When medications don’t effectively control symptoms, doctors may use Botox to reduce muscle spasms. Intravenous immunoglobulin (IVIg) treatment and other immunotherapies like stem cell treatment have also shown promise in improving symptoms by suppressing the autoimmune reaction suspected to cause SPS.

More research is needed to fully understand what causes SPS, including learning more about the specific role of anti-GAD antibodies. Researchers are also working to develop more effective treatments and ultimately find a cure for the disease.

Research on other brain diseases with overlapping symptoms—such as multiple sclerosis—will help us better understand the causes and symptoms of SPS and reduce the chances of misdiagnosis. Discoveries and research advancements for other autoimmune diseases and movement disorders will also lead to insights that will improve the diagnosis and treatment of SPS.