[Stiff-person syndrome: a case report].

Introduction: Stiff-person (stiff-man) syndrome is characterised by symptoms of muscular rigidity and spasms, which are generally of an axial nature. Involuntary contractions of the agonist and antagonist muscles caused by activity of the motor units during rest are the main clinical and electrophysiological marker of the disease. The nature of the syndrome is considered to be autoimmune, with positive glutamic acid decarboxylase (anti-GAD) antibodies in most patients.