[Stiff person syndrome associated with thymoma].

Stiff-person syndrome is a rare neurological condition characterized by muscular rigidity of the trunk and extremities and muscle spasms triggered by sensory or emotional stimuli, which progresses towards prostration. It has a pathophysiogenic mechanism with an immunological basis, in which autoantibodies, such as antiGAD65, play a central role. Likewise, the detection of these antibodies corroborates the diagnosis in a patient with a suggestive clinical picture. Four to 6% of cases have underlying neoplasms. Treatment is based on symptomatic, immunomodulatory, and underlying disease management in paraneoplastic cases. We report a case of classic stiff person syndrome associated with thymoma and review the main characteristics of this entity.