By Michelle Greer, RN, MBA

How many of you have heard of stiff-person syndrome (SPS)? SPS is believed to be an autoimmune disorder. It’s also known as stiff-man syndrome and Moersch Woltman syndrome, named for the physicians who discovered the condition. In an autoimmune disorder, the immune system malfunctions and creates antibodies that attack and cause damage to a part of the body. In SPS, an enzyme in the brain called GAD, or glutamic acid decarboxylase, is attacked. This enzyme is important in the synthesis of a neurotransmitter in the brain that causes nerve signals to send a message to the muscles to relax.   

Symptoms of SPS include muscle rigidity in the trunk and limbs, which frequently occur in response to some stimulus such as noise, touch, including heat or cold, and other physical and emotional stressors. The rigidity, caused by contracted muscles, can interfere with posture, balance and walking. People with SPS become anxious by the increased rigidity, which also interferes with their ability to complete everyday tasks. Rigidity can be mild or so severe that it causes pain and an inability to walk.

Diagnosing SPS is difficult because presenting symptoms can mimic other conditions such as Parkinson’s disease, multiple sclerosis or anxiety. Many cases are brushed off as psychosomatic. It may take years to definitively diagnose SPS. There is also some thought that some forms of SPS may be so mild, they may simply be diagnosed as a back or leg strain.

Diagnostic testing may include:

• Electromyography (EMG) to measure muscle activity

• Nerve conduction studies (NCS) to measure efficiency and speed of nerve signals

• Blood work to test for the anti-GAD antibody that may be present in SPS

Treatment of SPS may involve anti-seizure medications, muscle relaxants, anti-anxiety medications and/or intravenous immune globulin (IVIG). IVIG treatment should result in decreasing the attack on self and increased synthesis of GAD, allowing the muscles to relax. Muscle rigidity will subside and function will improve. A doctor will assess the response to therapy and determine how long a patient will be on it.

Tell us about your experience with SPS.

Additional Resources

• National Organization for Rare Disorders

• American Autoimmune Related Diseases Association