P.010 Extreme delta brush in anti-NMDAR encephalitis correlates with poor functional outcome and death

Background: The electroencephalography (EEG) pattern extreme delta brush (EDB) is felt to be highly specific for anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. This study aimed to characterize EEG findings in anti-NMDAR encephalitis patients looking for the proportion of abnormal EEGs, presence of EDB, and to relate EDB to clinical outcomes (Glasgow Outcomes Scale (GOS) at 6 months, need for ICU admission, and death). Methods: This retrospective single centre study included anti-NMDAR encephalitis patients who had ≥1 EEGs obtained from 2014-2021. EEGs were retrospectively analyzed by 2 reviewers. Clinical outcomes of interest were extracted through hospital and clinic chart review. Results: Twenty-one patients with anti-NMDAR encephalitis were included. Sixty-four EEGs were analyzed. Four EEGs (6.3%) were within normal limits. Focal or generalized slowing (without EDB) was seen on 44 EEGs (68.8%). EDB was seen on 16 EEGs (25.0%) in 9 of 21 patients. The presence of EDB was significantly associated with need for ICU admission (p=0.02), poorer outcome at 6 months as per the GOS (p=0.002), and with death (p=0.02) Conclusions: The presence of EDB on EEG in anti-NMDAR encephalitis patients is associated with increased need for ICU admission, risk of death, and worse functional outcomes at 6 months.