Anti-NMDAR encephalitis: demonstration of neuroinflammation and the effect of immunotherapy.

A 35-year-old man presented with perceptual difficulties and delusions. At presentation, there were orofacial dyskinesias, catatonia, and autonomic instability. Anti–NMDA receptor (NMDAR) antibodies were detected in CSF. Cerebral MRI was unremarkable. At the start of immunotherapy (methylprednisolone and plasmapheresis), [I]CLINDE-SPECT demonstrated a strongly increased binding to TSPO in cortical and subcortical brain regions similar to the distribution of NMDAR in the brain and different from FDG-PET changes reported in the literature (figure, A). TSPO is present on activated microglia and used as a measure of regional neuroinflammation. After 7 weeks of immunotherapy (figure, B), TSPO binding was close to normal values (figure, C) and the patient was back to work part time as a computer scientist despite mild cognitive problems.