A Metabolic Brain Pattern Associated With Anti-N-Methyl-D-Aspartate Receptor Encephalitis

Background: Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis causes substantial neurological disability. Autoantibodies causing encephalitis directed against the neuronal cell surface or synapse are of diagnostic importance giving the possibility of successful immunotherapy. Objective: In this study, we aim to provide supporting evidence that brain 18F-FDG-PET may be helpful in identifying likely patterns of regional brain glucose metabolism. Methods: Thirty-three patients (18 men and 15 women; age range of 17-55 y) with positive NMDA receptor antibody encephalitis that underwent an 18F-FDG-PET imaging examination were prospectively selected and compared with a reference group of 14 brain 18F-FDG-PET scans from healthy volunteers using voxel-based statistical analysis. Clusters of hyper- and hypo-metabolism were reported for the whole sample of patients (FWE-corrected P < 0.05), and uncorrected at P < 0.005 for a group of relapsed patients. Results: Mixed metabolic patterns (focal 1 bilateral hypermetabolism in the temporal lobe, insula, and cerebellum; associated with severe bilateral hypometabolism in the occipital and parietal lobes) were found. Conclusions: Our findings suggest that 18F-FDG-PET should be included as an imaging tool when assessing affected patients in the clinical workup to rule out anti-NMDA encephalitis and help determine the most effective treatment.