Stiff-person syndrome (SPS), also known as stiff-man syndrome, is a rare neurological disorder characterized by progressive muscle stiffness and rigidity, affecting primarily the trunk and limbs. It can also cause involuntary spasms, impaired balance, and difficulty walking. SPS is caused by a loss of inhibitory function in the central nervous system, leading to excessive muscle activity.
SPS has no specific cause, but it is thought to be an autoimmune condition. Autoimmune illnesses develop when the immune system of the body targets healthy tissues. The immune system assaults the component of the neurological system that regulates muscular action in SPS.
SPS is an uncommon illness that affects around one in a million people. Women are more likely to be affected than men. SPS symptoms often appear in maturity and intensify over time.