What is stiff person syndrome?

Stiff person syndrome is a rare autoimmune movement disorder that affects the central nervous system (the brain and spinal cord). People with this condition first experience a stiffening of the muscles of their trunk followed, over time, by the development of stiffness and rigidity in the legs and other muscles in the body.

Stiff person syndrome, also called Moersch-Woltman syndrome and formerly stiff man syndrome, can also cause painful muscle spasms. The muscle spasms occur randomly or can be triggered by noise, emotional distress and light physical touch.

Over time, stiff person syndrome can lead to an altered posture. Severe cases can limit your ability to walk or move. Some people with this disorder need ongoing treatment for years to manage symptoms and maintain quality of life.

Stiff person syndrome is thought to be part of a wide range of similar diseases that involve one area of the body and then spread throughout the body.

Who might get stiff person syndrome?

Stiff person syndrome is extremely rare. Only about one out of every one million people have been diagnosed this syndrome. Twice as many women have stiff person syndrome as men. Symptoms can occur at any age but usually develop between ages 30 and 60.

Stiff person syndrome is more likely seen in people with certain types of diseases including:

  • Autoimmune disorders including diabetes, thyroiditis, vitiligo and pernicious anemia.
  • Certain cancers including breast, lung, kidney, thyroid, colon and Hodgkin’s lymphoma.

What causes stiff person syndrome?

Researchers are not sure of the exact cause stiff person syndrome. However, they believe it to be an autoimmune disorder, a condition where your immune system attacks healthy cells. Many people with this disorder make antibodies that attack an enzyme called glutamic acid decarboxylase (GAD). GAD plays a role in making a neurotransmitter called gamma-aminobutyric acid (GABA), which helps control muscle movement. It is thought that the immune system in people with stiff person syndrome mistakenly attacks GAD enzyme, which decreases the amount of GABA in the body.

Antibodies to another protein called amphiphysin is a less common finding in people with this syndrome. This protein is found in nerve terminals and is involved in helping nerve cells communicate with each other.

The exact role that GAD plays in the development and worsening of stiff person syndrome is not totally understood. In fact, there are people with the syndrome that do not have detectable antibodies to GAD.

What are the symptoms of stiff person syndrome?

Symptoms of stiff person syndrome can take several months to a few years to develop. Some patients remain stable for years; other slowly worsen.

In most people with stiff person syndrome, the trunk and abdomen muscles are the first to become stiff and enlarged. Symptoms include pain, muscle stiffness and aching discomfort. Early on, stiffness may come and go but eventually the stiffness remains constant. Over time, leg muscles become stiff and more muscles throughout your body become stiff including the arms and even the face. As stiffness increases, some people developed a hunched posture. In severe cases, this stiffness can make it hard to walk or move.

Painful muscle spasms also occur. These spasms can last a few seconds, minutes or occasionally a few hours. Sometimes, the spasms can be severe enough to dislocate a limb, break a bone or cause uncontrolled falls. The spasms usually worsen the muscle stiffness. Spasms can occur for no reason or can be triggered when you’re exposed to an unexpected or loud noise, physical touch, cold environment or stressful event that causes an emotional response. The muscle spasms can involve the entire body or only a specific area. Sleep usually reduces the number of spasms.

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