Dementia-Like Presentation of Striatal Hypermetabolic State with Antistriatal Antibodies Responsive to Steroids

Background: Hypermetabolic lesions of the striatum are rare. They usually involve autoimmunity and are associated with choreatic disorders such as Sydenham chorea, lupus, and the antiphospholipid antibody syndrome. Patient: A 48-year-old woman was initially seen with a 1-year history of progressive changes in personality and attention. There were minor associated involuntary movements. Negative routine investigation results, including regular autoimmune serologies and magnetic resonance imaging, led to the diagnosis of a frontal dementia. Positron emission tomographic results demonstrated hypermetabolism in the left striatum. Western blot technique results demonstrated plasma antistriatal antibodies. Treatment with corticosteroids induced a resolution of her attentional deficits and a return of her personality to its premorbid state. The repeated positron emission tomographic scan results were near normal, and the titer of antistriatal antibodies was significantly reduced. Conclusion: Autoimmune striatal dysfunction can initially appear with a clinical picture suggestive of a degenerative dementia. Recognition of the underlying etiology and treatment was possible because of abnormalities uncovered on positron emission tomographic images.