Which are the causes of Stiff Person Syndrome?

Causes of Stiff Person Syndrome

Stiff Person Syndrome (SPS) is a rare neurological disorder characterized by muscle stiffness and spasms. The exact cause of SPS is not fully understood, but several factors have been identified as potential contributors to the development of this condition.

Autoimmune Dysfunction

One of the leading theories regarding the cause of Stiff Person Syndrome is an autoimmune dysfunction. The immune system, which is responsible for protecting the body against harmful substances, mistakenly attacks the body's own cells and tissues. In the case of SPS, it is believed that the immune system targets specific proteins involved in the communication between nerve cells and muscles, leading to the characteristic muscle stiffness and spasms.

Autoantibodies: Researchers have discovered the presence of autoantibodies in individuals with Stiff Person Syndrome. These autoantibodies target an enzyme called glutamic acid decarboxylase (GAD), which plays a crucial role in the production of gamma-aminobutyric acid (GABA), a neurotransmitter that inhibits nerve activity. The presence of these autoantibodies suggests an autoimmune response against GAD, disrupting the normal functioning of GABA and leading to muscle stiffness and spasms.

Genetic Predisposition

While Stiff Person Syndrome is not considered a hereditary disorder, there is evidence to suggest a genetic predisposition to developing the condition. Certain genetic variations may increase an individual's susceptibility to autoimmune dysfunction or make them more prone to developing SPS. However, it is important to note that having these genetic variations does not guarantee the development of the syndrome, as other factors likely play a role in its onset.

Environmental Triggers

Environmental factors may also contribute to the development of Stiff Person Syndrome. These triggers can potentially activate or exacerbate the autoimmune response in susceptible individuals. Some possible environmental triggers include:

• Infections: Infections, particularly viral or bacterial infections, have been linked to the onset of Stiff Person Syndrome. It is believed that the infection may trigger an autoimmune response, leading to the development of the condition.


• Physical or Emotional Stress: Stressful events, whether physical or emotional, can potentially trigger or worsen symptoms in individuals with SPS. Stress is known to have an impact on the immune system, and in susceptible individuals, it may contribute to the autoimmune dysfunction underlying the syndrome.


• Trauma: Traumatic events, such as physical injury or surgery, have been reported to precede the onset of Stiff Person Syndrome in some cases. The exact mechanisms by which trauma may trigger the condition are not fully understood, but it is thought to involve the activation of the immune system.

Other Factors

While the aforementioned factors are considered the primary causes of Stiff Person Syndrome, there are other potential contributors that require further research. These include hormonal imbalances, such as those associated with diabetes or thyroid disorders, as well as certain medications that may trigger or worsen symptoms in susceptible individuals.

Conclusion: Stiff Person Syndrome is a complex disorder with multiple potential causes. Autoimmune dysfunction, specifically the presence of autoantibodies targeting GAD, is considered a significant factor in the development of this condition. Genetic predisposition and environmental triggers, such as infections, stress, and trauma, may also play a role. Further research is needed to fully understand the underlying causes of Stiff Person Syndrome and develop more effective treatments for individuals affected by this rare neurological disorder.