Abstracts

Rationale: Autoimmune encephalitis such as anti-NMDA receptor encephalitis is rare disorder with limited data that often has delayed diagnosis. Earlier recognition and initiation of treatment has been shown to have improved outcomes. Current diagnostic modalities include testing for the antibodies that has a long turnaround time. Seizures and also altered mental status may prompt evaluation with EEG. Two series had shown adult patients and one pediatric patient with anti-NDMA receptor encephalitis had the “extreme delta brush” pattern (delta with superimposed bursts of rhythmic beta activity) and also had worse outcomes. We present 5 cases of anti-NMDA encephalitis, and the early EEG changes that could potentially help make earlier diagnosis and initiate treatment earlier.Methods: We reviewed EEGs of five pediatric patients with anti-NMDA receptor. We also reassessed the raw data for the EEGs that were available. Specifically, normal patterns, focal or generalized slowing, “extreme Delta brushes and seizures were noted. Time course of the evolution of abnormalities were also noted.Results: Of the five patients reviewed, extreme delta brushes were noted in 4 of 5 patients to have appeared early on in the recordings almost within a week of symptom onset. The next most common abnormality noted was focal slowing and evolution into generalized slowing and disorganization in all of these patients. Focal Spikes and multifocal seizures were noted in 3 of the 5 patients. One patient had absent sleep spindles noted throughout most of her EEG recordings.Conclusions: The EEG abnormalities noted in anti-NMDA encephalitis patients are not specific to the disease. When considered in combination with clinical presentation and the spectrum of abnormalities noted on EEG, the diagnostic workup and thereby treatment may be streamlined, thereby improving outcomes. The significance of abnormalities present in the studies was not recognized until recently and we are trying to assess this further.