Stiff-person syndrome (SPS) is a rare neurological disorder with features of an autoimmune disease.
SPS affects twice as many women as men. It is frequently associated with other autoimmune diseases such as diabetes, thyroiditis, vitiligo, and pernicious anemia.
SPS is characterized by:
- Fluctuating muscle rigidity in the trunk and limbs
- A heightened sensitivity to stimuli, which can set off muscle spasms. Stimuli include:
- Emotional distress
- Abnormal postures, often hunched over and stiffened
People with SPS can be too disabled to walk or move, or they are afraid to leave the house because street noises, such as the sound of a horn, can trigger spasms and falls.
Most individuals with SPS have frequent falls and because they lack the normal defensive reflexes. Injuries can be severe. With appropriate treatment, the symptoms are usually well controlled.
Scientists don’t yet understand what causes SPS, but research indicates that it is the result of an autoimmune response gone awry in the brain and spinal cord. The disorder is often misdiagnosed as Parkinson’s disease, multiple sclerosis, fibromyalgia, psychosomatic illness, or anxiety and phobia.
A definitive diagnosis can be made with a blood test that measures the level of glutamic acid decarboxylase (GAD) antibodies in the blood. People with SPS have elevated levels of GAD, an antibody that works against an enzyme involved in the synthesis of an important neurotransmitter in the brain.
There is no cure for SPS at this time. Treatment is aimed at reducing symptoms and includes:
- Medications, including:
- Anti-anxiety drugs
- Muscle relaxants
- Pain relievers
- Intravenous immunoglobulin (IVIg) treatment – reduces stiffness and lowering sensitivity to noise, touch, and stress in people with SPS