Antiphospholipid-Related Chorea: Two Case Reports and Role of Metabolic Imaging

Background: Antiphospholipid syndrome (APS) is a complex acquired autoimmune disease with a wide clinical spectrum. Chorea is a rare neurological manifestation of APS. Cases: We report two elderly patients with APS-related chorea in whom functional imaging (18F-FDG positron emission tomography, FDG-PET) supported the diagnosis and compare our findings with existing literature. Literature Review: Among 142 clinical cases of antiphospholipid-related chorea found in literature, only 10 had undergone brain metabolic imaging. Striatal hypermetabolism was evident in all cases (6) that underwent FDG-PET cerebral imaging. Cerebral perfusion single photon emission computed tomography (SPECT) was normal in two cases, while the other two presented with basal ganglia hypoperfusion. Conclusions: Brain FDG-PET usually shows striatal hypometabolism in neurodegenerative types of chorea as opposed to striatal hypermetabolism observed in most cases of chorea from reversible etiologies, such as APS-related chorea. When a patient's clinical presentation is not clearly suggestive of either a neurodegenerative or autoimmune chorea, and first-line investigations are normal, FDG-PET may help in the differential diagnosis, especially in the presence of striatal hypermetabolism. SPECT data are less numerous and show either normal scans or basal ganglia hypoperfusion.