What is Stiff-Person Syndrome?

Since the announcement that singer Celine Dion had been diagnosed with a rare neurological disorder called stiff-person syndrome (SPS), online discussion of the disorder has skyrocketed.

Fewer than 5,000 people are living with the disorder in the United States, according to the Genetic and Rare Diseases Information Center. Of the people who are diagnosed with SPS, women are twice as likely to be diagnosed as men.

We asked James Shou, MD, a neurology specialist with Rochester Regional Health, to discuss the disorder, how it is diagnosed, and what treatments are currently available.

What is stiff-person syndrome?

Stiff-person syndrome (SPS) is a rare progressive disease that affects the body’s nervous system – specifically the spinal cord and brain. Adults are most often diagnosed with this syndrome.

Symptoms of SPS display as:

• Extreme muscle stiffness or rigidity
• Painful spasms in the torso and limbs
• Heightened sound sensitivity
• Abrupt movements
• Emotional distress & anxiety
• Increased falls
• Atypical spinal posture

While an exact cause is not yet known, the National Institute of Neurological Disorders and Stroke suggests a faulty autoimmune response in the brain and spinal cord may be related, causing the body to attack nerve cells that control muscle movement. Stiff-person syndrome is often associated with other autoimmune diseases such as Type 1 diabetes, thyroiditis, vitiligo, and pernicious anemia.

Diagnosing stiff-person syndrome

A patient’s primary care provider will often refer them to a specialist based on their symptoms.

Since the disorder is so rare, stiff-person syndrome is typically diagnosed by first ruling out other, more common disorders or illnesses such as anxiety and phobia, fibromyalgia, multiple sclerosis, Parkinson’s disease, or psychosomatic illness, according to the National Institute of Neurological Disorders and Stroke.

A neurological specialist can definitively diagnose SPS using a combination of techniques, including a comprehensive physical and neurological exam, an electromyography (EMG) of the muscles to help rule out look-alike conditions, as well as a blood test to measure levels of a special protein called a glutamic acid decarboxylase (GAD) antibody. GAD antibodies are often significantly elevated in diabetic patients; for SPS patients, GAD antibody levels are at least 10 times above the range seen in diabetes. However, the antibodies may not be present in up to a third of patients.

“With rare disorders, finding an exact diagnosis may prove challenging because one or two symptoms may point to several potential illnesses,” Dr. Shou said. “Our neurologists collaborate with patients and their primary care providers to take in as much information as possible in order to identify and treat their symptoms.”

Treatment and research

While there is no cure for stiff-person syndrome, therapies and treatments are available to ease some of the symptoms and manage pain.

Drugs such as oral diazepam can be prescribed to relieve anxiety and relax muscles, while others such as baclofen or gabapentin ease muscle spasms. A recent National Institute of Neurological Disorders and Stroke-funded study showed intravenous immunoglobulin (IVIg) treatment helps to reduce stiffness, noise and touch sensitivity, and improving gait and balance for SPS patients.

There are currently a small number of clinical trials underway in the U.S. and France related to stiff-person syndrome.