By Steven Vernino, M.D., Ph.D.
Vice Chair for Education & Faculty Affairs
Neurology
Pop superstar Celine Dion’s announcement that she was canceling her 2023 tour due to a diagnosis of stiff person syndrome (SPS) has focused the spotlight on this extremely rare autoimmune neurologic disorder.
SPS causes progressive muscle stiffness and severe muscle spasms that can lead to chronic pain, falls, and loss of mobility over time. In some cases, spasms are so severe they can cause falls, broken bones, and dislocated joints. While this rare condition is not fatal, its symptoms can dramatically affect a person’s quality of life.
When we say stiff person syndrome is rare, that is an understatement; it affects one in a million people.
UT Southwestern is one of about 20 referral centers in the entire country for SPS, which means our neurologists see a higher volume of cases than the average health center. To put that in perspective, we provide ongoing care for about 20 patients with SPS and see many other patients for neurological consultation for SPS or possible SPS.
It is possible more people have SPS than reported. The condition can go unrecognized or be misdiagnosed as back injury, multiple sclerosis (MS), muscular dystrophy, Parkinson’s disease, or fibromyalgia.
Because SPS is so rare, its complexities are still somewhat mysterious. Research indicates that SPS is associated with high levels of antibodies (blood proteins that are produced to protect the body against infections). However, in the case of SPS, these antibodies are autoantibodies that target normal parts of the body. In the majority of SPS patients, the autoantibodies target an enzyme called glutamic acid decarboxylase (GAD or GAD65). Other autoantibodies have also been reported in SPS.
Up to 80% of people with stiff person disorder have GAD autoantibodies in their blood. The GAD enzyme is found in many cells of the body, but it is also found in certain nerve cells where the GAD enzyme helps make gamma-aminobutyric acid (GABA), a neurotransmitter that helps slow down brain activity. One theory is that the immune system and autoantibodies causes less GABA to be available – causing overactive nerves that signal the muscles to become stiff, rigid, and continuously contract.
SPS is more common in women, and symptoms generally begin between the ages of 30 and 60. These features are common in other autoimmune diseases, too. People with SPS often have other autoimmune conditions including diabetes, thyroiditis, vitiligo, myasthenia gravis, and pernicious anemia. In some cases, symptoms of SPS can occur in patients with certain cancers including breast, lung, kidney, thyroid, colon, and lymphoma.
Though there is no cure for stiff person syndrome, medications to help relax the muscles – and in more severe cases, immunotherapy – can help patients manage their symptoms and return to regular activities – whether that’s returning to work, playing with the grandkids, or singing on stage.
Symptoms of stiff person syndrome
SPS is characterized by dramatically stiff muscles in the back, chest, abdomen, or arms and legs. These are not your garden variety back spasms or muscle aches that we all experience from time to time. SPS patients’ back muscles can feel as hard and inflexible as steel rods.
On top of this, muscle spasms in SPS can occur unexpectedly and can last for seconds or hours. They are often triggered by cold temperatures, unexpected loud noises, physical touch, or emotional stress. In the most severe cases, the spasms can dislocate joints, break bones, or cause a patient to fall.
Also in more severe cases, the muscle spasms and stiffness can spread to other muscle groups (especially the legs), and patients may develop difficulty walking. Some patients also develop anxiety or depression, or agoraphobia (fear of going outside), which is not uncommon for patients with rare, complex conditions.
Diagnosis and treatment of SPS
The exact role of the GAD enzyme and GAD antibodies in stiff person syndrome isn’t fully understood – approximately 20% of patients with the condition do not have GAD antibodies. Conversely, many people with GAD antibodies don’t have SPS (for example, millions of people with Type 1 diabetes in the U.S. likely have GAD antibodies).
There are specific tests and exams a health care provider can order to rule out other more common conditions, such as MS or fibromyalgia. Some of these include:
- Blood test to check for antibodies to GAD.
- Lumbar puncture (spinal tap) to check for antibodies to GAD in the cerebral spinal fluid or signs of inflammation.
- Electromyography (EMG) to measure electrical activity in the muscles – SPS decreases muscle relaxation, not muscle strength.
Treatment for SPS focuses on managing symptoms, reducing pain, and improving mobility. Neurologists usually start by prescribing muscle relaxants, such as diazepam o lorazepam (which help activate the GABA receptor) or baclofen. In SPS, very high doses of muscle relaxants are sometime required.
Some patients do well with muscle relaxants alone. For more severe cases, patients may need immunotherapy or immunosuppressant medications to reduce GAD antibodies. These could include intravenous immunoglobulin (IVIG), plasmapheresis, or rituximab. However, because SPS is rare, very few clinical trials have been done to prove the benefits of these treatments.
Non-medication treatments such as physical therapy, occupational therapy, aqua therapy, and acupuncture may provide relief from muscle pain. Cognitive behavioral therapy may help patients avoid or better handle the emotional triggers that can cause muscle spasms. It also can help them develop skills for living with a chronic condition like SPS.
Treatment is very personalized, and many patients can function well and get back to many, if not all, of their normal activities once an optimal combination or therapies is found.
What to do if you suspect you have SPS
Primary care physicians and most neurologists rarely see cases of stiff person syndrome, so it’s not uncommon for a diagnosis to take a while. Celine Dion noted in an emotional Instagram post that she had “been dealing with problems with my health for a long time.”
If you’re experiencing persistent muscle spasms or severe stiffening of the muscles in your back, abdomen, arms, legs, or face, talk with a doctor about whether you should get a GAD antibody test. And if you have another autoimmune disorder, mention it in your conversation. If you and your doctor think you might have SPS, ask for a referral to an academic medical center like UT Southwestern, where you will find specialists with expertise in rare disorders.
UT Southwestern’s O’Donnell Brain Institute offers one of a handful of autoimmune neurology fellowships in the U.S. to train the next generation of neuroimmunologists. Specialized centers such as ours also conduct clinical trials to improve treatment for autoimmune neurological disorders. For example, we participated in a multicenter study in which we identified the pressing need for stringent diagnosis criteria and testing for neuroimmunological conditions. These diseases are typically rare and can easily be misdiagnosed, leading to ineffective treatment and continued brain inflammation.
The media coverage of Celine Dion’s announcement has increased attention to SPS and could potentially accelerate research efforts. While SPS can affect almost every aspect of daily life, we can help you find a personalized treatment plan to get back to doing what you love with less stiffness and pain.
Talk with your doctor about getting a referral, or call 214-645-8300 or request an appointment online.
