Stiff person syndrome (SPS) is a rare autoimmune neurological disorder that causes muscle spasms and stiffness. SPS affects the way your brain and spinal cord control muscle movements.

On December 8, 2022, Canadian singer Celine Dion revealed that she has been diagnosed with SPS.

“While we’re still learning about this rare condition, we now know this is what’s been causing all of the spasms that I’ve been having. Unfortunately, these spasms affect every aspect of my daily life, sometimes causing difficulties when I walk and not allowing me to use my vocal cords to sing the way I’m used to,” Dion said in her announcement on Instagram.

What is SPS exactly? Read on to learn about the causes and treatment for this condition.

An autoimmune disorder occurs when your immune system incorrectly identifies healthy body tissues as harmful and attacks them.

SPS causes you to experience uncontrolled episodes of muscle spasms and stiffness. It is a progressive disorder that can ultimately impede walking and other basic daily functioning skills.

SPS can significantly interfere with your quality of life without proper treatment. However, it is a rare disorder affecting only about 1-2 people per million. It has been described as starting between the ages of 30 and 60 and appears to be more common in females.

Most notably, SPS causes muscle stiffness. The symptoms include:

  • limb stiffness
  • stiff muscles in the trunk
  • posture problems from rigid back muscles that can cause you to hunch over
  • painful muscle spasms
  • walking difficulties
  • sensory issues such as sensitivity to light, noise, and sound

SPS spasms can be very strong and may cause you to fall if standing. They can sometimes be strong enough to break bones. The spasms may be worse when you’re anxious or upset. Sudden movements, loud noise, or touching can also trigger involuntary spasms.

When you’re living with SPS, you may also have depression or anxiety. This may be caused by other symptoms you might be experiencing or a decrease in neurotransmitters in the brain.

The potential for emotional distress can increase as SPS progresses. You may notice the spams worsen when you’re out in public. This may lead you to develop anxiety about going out in public.

You may experience increased muscle stiffness and rigidity in the later stages of SPS. Muscle stiffness can also affect other body parts, such as your face. This can include muscles used for eating and talking. Muscles involved in breathing may also be affected, causing life threatening breathing problems.

People with SPS have antibodies that attack proteins in the brain neurons that control muscle movements. These proteins can be glutamic acid decarboxylase (GAD), gephyrin, or gamma-aminobutyric acid (GABA).

The reason some people develop SPS is unknown. There are some risk factors, but not everyone who develops SPS has the associated risk factors.

SPS may co-exist with other autoimmune diseases such as pernicious anemia, vitiligo, type 1 diabetes, celiac disease, and autoimmune thyroid disease.

Your symptoms may vary depending on the type of SPS you have. Other than its classic presentation, which affects 70% to 80% of people with SPS, SPS can present as:

  • Focal stiff person syndrome: This typically affects only one limb.
  • Jerking stiff person syndrome (progressive encephalomyelitis with rigidity). This can affect the control of your eye and head muscles.
  • Progressive encephalomyelitis with rigidity and myoclonus (PERM): Similar to classic stiff person syndrome but can be associated with cancerous tumors.
  • Paraneoplastic-related stiff person syndrome: This variant is associated with breast cancer, colon cancer, thyroid cancer, lung cancer, as well as Hodgkin and non-Hodgkin lymphomas. However, it tends to manifest before the cancer itself and is caused by a different antibody than classic SPS.

To diagnose SPS, your doctor will examine your medical history and perform a physical exam. Signs of SPS are:

  • stiffness in your limbs or the axial muscles
  • spasms that are triggered by things like noise or your mental state

They will consider other causes of movement problems with muscle spasms, such as multiple sclerosis (MS) and Parkinson’s disease, which have their own diagnostic criteria. SPS might be considered when the signs and symptoms don’t fit with more common neurological conditions.

The doctor may also do electromyography (EMG) to measure your muscular electrical activity.

Your doctor may also order a blood test to detect the GAD or other antibodies. Not everyone with SPS has these antibodies. However, up to 80% of people living with SPS do have elevated GAD antibodies.

There’s no cure for SPS. However, treatments are available to help you manage your symptoms. Certain treatments may also stop the condition from getting worse. Muscle spasms and stiffness may be treated with one or more of the following medications:

  • muscle relaxers such as baclofen
  • benzodiazepines such as diazepam(Valium) or clonazepam (Klonopin).
  • anti-seizure medications like gabapentin (Neurontin)
  • anticonvulsants such as pregabalin (Lyrica)

You may also need to take medications for pain and discomfort. Antidepressants like selective serotonin reuptake inhibitors (SSRIs) may also help with depression and anxiety.

Additional treatments have been shown to help prevent the disease process of SPS. These include:

  • Autologous stem cell transplant: Thisis the process where your blood and bone marrow cells are collected and multiplied before transferring back to your body. This promotes the creation of immune cells that do not causes the SPS autoimmune process. This is an experimental treatment, but it has shown some success.
  • Intravenous immunoglobulin: This treatment can decrease the number of antibodies that attack healthy tissues.
  • Plasmapheresis: This is a procedure in which your blood plasma is traded with new plasma to reduce the number of antibodies in the body.
  • Immune-suppressing drugs: This includes rituximab (Rituxan) and tacrolimus.

In addition to medications, your doctor may refer you to a physical therapist. Physical therapy alone can’t treat SPS. However, the exercises may significantly help with your:

  • emotional well-being
  • walking
  • independence
  • pain
  • posture
  • overall day-to-day function
  • range of motion

Depending on your symptoms, your physical therapist will guide you through mobility and relaxation exercises. With the help of your therapist, you may even be able to practice some movements at home.

If you’re living with this condition, you’re more prone to falls because of a lack of stability and reflexes. This can increase your risk for severe injuries and even permanent disability.

Occasionally, SPS can progress and spread to other areas of your body.

There’s no cure for SPS. However, treatments are available to help you manage your symptoms. Your overall outlook depends on how well your treatment plan works.

There are different treatments, and it isn’t possible to predict with certainty which treatments will be most effective for you.

Discuss your symptoms with your doctor. It’s especially important to discuss any new symptoms you’re experiencing or if you aren’t seeing any improvements. This information can help them choose the best treatment plan for you.