A rare stiff person spectrum disorder characterized by painful episodic spasms (which are often precipitated by touch, pain, cold, movement, or negative emotions), increased stimulus sensitivity including hyperekplexia, as well as stiffness, in a lower or upper limb, typically with insidious onset and progression over months or years. The condition may eventually progress into classic stiff person syndrome. Fear of leaving the house and walking unaided is characteristic. Most patients have autoantibodies in serum and CSF, in particular anti-glutamic acid decarboxylase (GAD) antibodies. In rare cases, the syndrome is of paraneoplastic origin. [from
ORPHANET]