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

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.

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.

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.

Mixed metabolic patterns (focal/bilateral hypermetabolism in the temporal lobe, insula, and cerebellum; associated with severe bilateral hypometabolism in the occipital and parietal lobes) were found.

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.