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Celine Dion is canceling and rescheduling her 2023 tour dates after revealing that she had been diagnosed with a rare neurological autoimmune condition called stiff person syndrome (SPS). Dion shared in an emotional Instagram video in December 2022 that she had been struggling for some time with vague symptoms before receiving the diagnosis.
SPS is quite rare, affecting about one in 1 million people. Since 2017, our system has only seen approximately 100 people with a suspected SPS diagnosis.
While SPS itself is not fatal, it can be debilitating. Patients experience severe spasms that make the muscles—often in the back and sometimes the limbs—tense up so much that they feel like wood or steel. Muscle spasms can occur spontaneously or because of a trigger, such as:
- Loud noises
- Being touched
- Cold temperature
- Stress
Symptoms can range from mild spasms that hinder social and physical quality of life to severe spams that cause chronic pain, slumped posture, inflammation, and limited mobility. In the worst cases, intense or prolonged spasms can dislocate a patient’s joints or break their bones. It’s not unusual for patients with SPS to develop anxiety or depression.
Because SPS is rare and its symptoms overlap with more common conditions such as Parkinson’s disease, patients can be misdiagnosed for years before finding their true diagnosis.
However, rare as it is, SPS can be diagnosed through a few specific tests. And while there is not a cure, effective treatment from a neurologist or with a rheumatologist with expertise in autoimmune disorders can help manage patients’ debilitating muscle spasms.
What causes stiff person syndrome?
SPS is an autoimmune disease that that affects the nervous system. This means that the patient has antibodies that attack the patient’s body, rather than having an infection or another disease.
Researchers have found that SPS is associated with high levels of an autoantibody that attacks an enzyme called serum antiglutamic acid decarboxylase (GAD-65). That enzyme helps make GABA, which is a neurotransmitter that slows brain activity. A high level of those autoantibodies leads to less GAD-65 and therefore less GABA, which researchers think results in overactive nerves that signal the muscles to contract too much and stiffen. There is also another form that can be associated with breast cancer.
How we diagnose SPS.
One of the first steps is to talk about symptoms—when they happen, what triggers them, and what they feel like. This can help us rule out other conditions with similar symptoms, such as Parkinson’s disease, fibromyalgia, or multiple sclerosis.
The doctor will order a blood test to check for a high level of GAD-65 autoantibodies. About 80% of patients with SPS have a high reading—but that doesn’t automatically mean they have SPS. Patients with diabetes often have high GAD-65 autoantibodies levels, and very few will have SPS.
Our specialists can also order an electromyography (EMG) to check the electrical activity in the muscles. We look for muscles tightening when they should relax. For example, when you flex your bicep, the triceps should relax. If both tense up, it could be a sign of a muscle or nerve problem.
Combined, these tests can give us enough information to diagnose SPS. But it is possible to have SPS and another medical condition. So, some patients might need more tests or exams. For example, patients who have or had breast cancer may also get a blood test for amphiphysin antibodies, which are associated with breast cancer and SPS.
Frustrating, yet treatable.
SPS symptoms alone can be debilitating; the overlapping psychosocial implications make it harder to manage. Patients who are triggered by noise or touch may develop depression or feel anxious about leaving home.
But with expert treatment, most patients with SPS do very well. Many can go back to work in the right environment.
Most patients start with benzodiazepine, a muscle relaxant. But people with SPS may need up to five times the typical dose to lower their muscle tension and relieve symptoms. Despite the high dose, patients usually adjust well and can function well. In some cases, patients may benefit from baclofen, a pill or spinal injection to relax the muscles.
Some patients benefit from monthly intravenous immune globulins (IVIG), which clears out the antibodies that cause SPS. A study published in Neuroimmunology and Neuroinflammation in July 2022 found that about 67% of patients responded to IVIG treatment over 3.3 years, with improvements in gait, posture, painful spasms, and startle response.
Another option is Rituximab, which is more potent that IVIG but acts similarly to clear the antibodies that cause SPS.
Because SPS symptoms and autoantibody levels can vary, it’s possible that more people have it than current estimates suggest. By the same token, some people diagnosed with SPS may have another neurological condition characterized by stiffness and rigidity, such as Parkinson’s disease or muscle dystonia.
With such a small number of patients, it is difficult to conduct big clinical trials to study SPS. But as we learn more about genetic and autoimmune disease drivers, we will better understand how to treat—and maybe even cure—neuroimmune conditions such as stiff person syndrome.
