Electroencephalographic and fluorodeoxyglucose-positron emission tomography correlates in anti-N-methyl-d-aspartate receptor autoimmune encephalitis

Abstract

ImportanceAnti-N-methyl-d-aspartate receptor (anti-NMDAR) autoimmune encephalitis is an increasingly recognized cause of limbic encephalitis (LE). Prolonged LE and limbic status epilepticus (LSE) share many features. The ability to distinguish between the two is crucial in directing appropriate therapy because of the potential iatrogenesis associated with immunosuppression and anesthetic-induced coma.ObservationsA 34-year-old woman with recurrent LE developed behavioral changes, global aphasia, and repetitive focal and generalized tonic–clonic seizures. Because asymmetric rhythmic delta patterns recurred on electroencephalography (EEG) despite treatment with nonsedating antiepileptic drugs followed by anesthetic-induced coma, an investigation to distinguish LSE from LE was undertaken. Implanted limbic/temporal lobe depth electrodes revealed no epileptiform activity. Brain single-photon emission computerized tomography (SPECT) showed no hyperperfusion, and brain fluorodeoxyglucose-positron emission tomography (FDG-PET) showed hypermetabolism in the left frontal, temporal, and parietal cortices. Anti-N-methyl-d-aspartate receptor autoimmune encephalitis was diagnosed based detection of anti-NMDAR antibody in the cerebrospinal fluid (CSF). With chronic immunosuppression, the resolution of brain FDG-PET abnormalities paralleled clinical improvement.Conclusions and relevanceThis case of anti-NMDAR autoimmune encephalitis illustrates the challenges of distinguishing prolonged LE from LSE. We discuss the parallels between these two conditions and propose a management paradigm to optimize evaluation and treatment.

Diagnostic Value of18F-FDG PET/CT Versus MRI in the Setting of Antibody-Specific Autoimmune Encephalitis

“…However, a heterogeneous pattern of brain metabolism has been reported on the brain 18 F-FDG PET/CT of patients with AE so far (34)(35)(36)(37)(38). Some previous case reports described hypermetabolism of cerebral cortices or striatum as a predominant feature of autoimmune encephalitides (35,(37)(38)(39). This may in part be due to the fact that we are measuring the metabolic activity of entire lobes/predetermined regions by Cortex ID.…”

FDG-PET hyperactivity pattern in anti-NMDAr encephalitis

“…Although this pattern appears to be highly suggestive of NMDAr encephalitis, some cases showing different abnormalities such as lateralised/focal areas of hyper-or hypometabolism were also reported 7 . This discrepancy seems not to be explained by parenchymal lesions in cases with focal alteration of metabolism.…”

“…There are suggestions that the intensity of the PET abnormalities correlates with the severity of the disease at least within the course of a single episode 5,7 . This may render FDG-PET a useful addition to the diagnostic of relapses.…”

Common EEG Patterns in Autoimmune Encephalitis and Paraneoplastic Neurological Syndromes

“…ise tekrarlayıcı limbik ensefalit atakları olan BOS bakısında anti-NMDAR antikorları saptanan bir hastada yüzeyel EEG'de afazi ve sağ kol güçsüzlüğü ile korele sol temporal bölgede, epileptifom deşarjların eklenmediği aralıklı delta aktivitesi izlemişlerdir. [35] Antiepileptik ve immünsupresif tedaviye dirençli bu EEG aktivitesi sol amigdala ve hipokampus yerleşimli derinlik elektrodları ile değerlendirildiğinde yüzeyel EEG aktivitesi ile korele neredeyse devamlı semi-ritmik ya da ritmik delta aktivitesi izlenmiştir. Bu aktivitenin anti-NMDAR ensefalitinde NKSE'ye işaret edebileceği belirtilmiştir.…”

“…Bu aktivitenin anti-NMDAR ensefalitinde NKSE'ye işaret edebileceği belirtilmiştir. [35] Sakakibara ve ark. status epileptikus sonrası 14 aydan uzun süren sağ hemisferik periyodik lateralize epileptiform deşarjlar (PLED) ve eşlik eden hafif sol hemiparezisi ve sol hemispasyal ihmali olan bir hastada BOS'ta NMDAR antikorları saptamışlardır.…”