Stiff Person Syndrome Awareness Day Date in the current year: March 15, 2025

Stiff person syndrome (SPS) is an extremely rare disorder that affects approximately one or two in a million people. It causes muscle stiffness (hence the name) and painful muscle spasms that come and go and get worse over time. It most often develops in middle age.

SPS was first described in 1956 by American neurologists Henry Woltman and Ferderick Moersch, who had observed 14 cases of the syndrome over three decades. They originally named it “stiff-man syndrome”. Diagnostic criteria for the syndrome were adopted in 1989, and two years later it was renamed stiff person syndrome to make the name gender-neutral.

SPS has three subtypes. Approximately 70% of people with SPS have classic SPS, which is characterized by muscle stiffness and spasms that begin in the trunk and eventually progress to the limbs. Partial SPS, also called stiff limb syndrome, is characterized by stiffness and spasms in the limbs or a single limb. It progresses to full SPS in about 25% of cases. The third subtype of SPS is progressive encephalomyelitis with rigidity and myoclonus, which involves inflammation of the brain and spinal cord.

There is no cure and no evidence-based treatment for SPS because the condition is too rare to conduct large, controlled trials and establish treatment guidelines. Treatment strategies typically include benzodiazepines and other medications to control spasms, immunotherapy for patients who do not respond well to anticonvulsant medications, and physical therapy.

Even with early diagnosis and treatment, SPS generally leads to an eventual decline in quality of life. Approximately two-thirds of patients with SPS are unable to function independently, and approximately 10% require of intensive care at some point. Muscle stiffness and spasms eventually begin to affect a person’s posture, balance, and gait and to consistently impair mobility, leaving some patients unable to bend or walk. Most patients also experience chronic pain, and some develop vision or speech issues.

Stiff Person Syndrome Awareness Day has been observed since the mid-2010s, but it gained widespread attention in 2024, when Canadian singer Céline Dion shared an Instagram post in honor of SPS Awareness Day. Dion was diagnosed with SPS in August 2022 and went public with her diagnosis in December. She has been open about her struggles, saying the disease has affected all aspects of her life, including her ability to sing. A documentary about Dion’s life, including her battle with SPS, titled I Am: Céline Dion, was released in 2024.

The main goal of SPS Awareness Day is to raise awareness of this rare and complex condition, support patients with SPS and rare families, and highlight the importance of research into the syndrome to find a cure.