Stiff-person syndrome is a rare progressive neurological disorder characterized by constant painful contractions and spasms of voluntary muscles, particularly the muscles of the back and upper legs. Symptoms may occur gradually, spreading from the back and legs to involve the arms and neck. Symptoms may worsen when the affected individual is anxious or exposed to sudden motion or noise. Affected muscles may become twisted and contracted, resulting in bone fractures in the most severe cases.
Sleep usually suppresses frequency of contractions.
Researchers theorize that stiff-person syndrome may be an autoimmune disorder. The drug diazepam, which relaxes the muscles, provides improvement in most cases. Baclofen, phenytoin, clonidine, or tizanidine may provide additional benefit. Physical and rehabilitation therapy may also be needed. There is no cure for stiff-person syndrome.