Stiff-person syndrome is a rare neurological disorder involving muscle stiffness and spasms, according to WebMD. Other names for stiff-person syndrome include stiff-man syndrome or Moersch-Woltman syndrome.
As of 2015, doctors don't know the cause of stiff-person syndrome, but they believe it is an autoimmune disorder, says WebMD. Those with the disorder experience episodes of muscle stiffness and spasms, which occur spontaneously or in response to a stimuli such as a light touch or a loud noise. Stiff-person syndrome affects more women than men. Benzodiazepine medications, which relax muscles and which doctors usually prescribe for anxiety, are the most common treatment for the syndrome according to Wikipedia.