[Two stiff person cases misdiagnosed as conversion disorder].

Modern psychiatric diagnostic systems classify neurological symptoms that cannot be explained by a physical disease or another psychiatric disorder as conversion disorder (CD) or dissociative motor disorder. It is a well-known fact that the overall rate of misdiagnosis of conversion symptoms is high. The most common presenting symptoms of misdiagnosed patients are gait and movement disturbances. Stiff-person syndrome (SPS) is a rare progressive autoimmune neurological disorder. The identification of antibodies against glutamic acid decarboxylase (GAD) in association with SPS provided an important contribution to the understanding of the pathophysiology of this syndrome. Patients may present with severe muscle rigidity and sudden contractions. Simultaneous contraction of agonist and antagonist muscles produces gait disturbance. SPS can be exacerbated by emotional stressors, and sudden auditory, visual, and tactile stimuli. Herein we present 2 patients that were referred for psychiatric assessment, because their neurological symptoms initially could not be explained by a neurological disease, and subsequently diagnosed as SPS. The aim of this case report is to draw attention to the psychiatric presentations of SPS and to emphasize the importance of complete psychiatric and neurological examination, including brain imaging and electrophysiological studies, in the differential diagnosis of CD.