====== Stiff person syndrome ======

//Stiff Person Syndrome// (SPS) is a progressive neurological autoimmune disorder which leads to  involuntarily muscle contractions (and subsequently rigidity) which can severely affect range of motion.

It's classed as a rare disease, nevertheless at any one time, it's estimated that around 1 million people are affected by the syndrome - and many more are mis-diagnosed as suffering from other problems such as [[content:medicine:diseases:m-q:ms]], [[content:medicine:diseases:m-q:parkinsons]], [[content:medicine:diseases:a-f:fibromyalgia]], psychosomatic illness, anxiety and phobia.

It was first described in the mid 1950s and is frequently associated with other autoimmune diseases such as type-I diabetes, thyroiditis, vitiligo, and pernicious anemia.

The cause is not known.

One significant (though unexplained) factor is that sufferers often have very elevated levels of antibodies to an enzyme known as glutamic acid decarboxylase or GAD. (GAD is an important component of the mammalian nervous system, with a crucial role in the nerve signalling process). Although these high GAD antibody levels are quite rare in the general population, most of those who //do// have them //do not go on to develop SPS. //Suggesting that the levels of antibodies might be a symptom of the disease rather than a cause.

Further information: [[https://www.ninds.nih.gov/health-information/disorders/stiff-person-syndrome|US NIH]]