What you need to know about stiff person syndrome (SPS)

Celine Dion posted an emotional video to her Instagram account on December 8, announcing she has been living with stiff person syndrome (SPS) for some time. 

"While we are still learning about this condition, we know now it's been causing all the spasms I've been having… it's been really difficult to face these challenges," she said in the video.

But what is SPS? DW has the answers.

1) How rare is SPS?

SPS is very rare, affecting roughly one in one million people. While it is more prevalent in women, the risk factors for being diagnosed with SPS are unknown

2) What are the symptoms?

SPS causes painful muscle spasms as well as rigidity and stiffness in the muscles of the body. SPS symptoms usually begin to appear in adulthood. Over time, the stiffness gets progressively worse, leading to hunched posture and, in some cases, severe disabilities in moving and walking.

Spasms can occur randomly or in response to sudden noise, light or physical contact. The spasms can last for minutes or even hours. Chronic pain is also common.

3) What's it like to live with SPS?

Dion said in her video that spasms affect her ability to walk. She also said the disease impacts her vocal cords, making it impossible to sing as she once could.

SPS patients often become severely disabled and lose their ability to walk. Muscle spasms can be severely painful and debilitating, leading many with the disorder to fear leaving their homes, out of worry over unanticipated outbreaks of severe spasms.  As such, depression, anxiety and phobias are common.

Dion's video has prompted people on social media to share their own experiences of living with SPS.

4) What causes SPS?

Scientists don't yet understand what causes SPS, but research indicates that it is the result of an autoimmune response gone wrong in the brain and spinal cord.

Patients with SPS often have high levels of an antibody called glutamic acid decarboxylase (GAD) in their blood. Experts think the antibodies cause a blockade of the neurotransmitters inhibiting electrical excitability in the brain.

This causes the neurons controlling muscle movement (motor neurons) to activate involuntarily, causing uncontrolled muscle contraction and spasms.

5) Is there a cure or treatment?

There are no known ways to cure SPS, but the symptoms of the disease can be treated with a variety of different drugs.

Medications  like diazepam and benzodiazepines are the primary treatment for SPS. These drugs have a muscle relaxant and anticonvulsant effect. They work by increasing the effectiveness of inhibitory neurotransmitters in the brain, helping it control involuntary motor neuron action.

Some therapies also target autoimmune responses in patients with the aim of stopping the patient's own GAD antibodies from blocking neurotransmitters in the brain.

Edited by: Clare Roth