Abstracts

Rationale: To describe the progression of initial EEG changes during the early stages of anti-NMDA receptor encephalitis (anti-NMDARE). Anti-NMDARE is an autoimmune syndrome caused by antibody against NMDA receptor. Patients present with encephalopathy, psychiatric symptoms, and/or seizures. Early initiation of therapy portends better prognosis. Therefore, early biomarkers and tracking their evolution through disease progression is critical. The EEG pattern of extreme delta brush (EDB) is a finding specific to anti-NMDARE; however, little is known about its temporal features.

Methods: Retrospective chart review was performed.

Results: A previously healthy 20 year-old woman developed flu-like symptoms 4 days prior to presentation. Three days later (Day 0, onset of symptoms), she developed psychosis and was admitted to psychiatry ward. Neurology was consulted on Day 6 when she developed intermittent staring episodes with lip smacking.

EEG on Day 6 showed normal 9-10 Hz background (Fig 1A). After several hours, mixed frequency alpha-theta activities emerged with preserved sleep architecture (Fig 1B) and no epileptiform abnormalities. CSF studies showed WBC 46 (92% lymphocytes), RBC 1, glucose 63, and protein 41. CSF NMDA Ab IgG was 1:320. On exam, patient followed commands and answered simple questions.

On Day 9, she no longer followed commands. EEG showed diffuse persistent semi-rhythmic delta frequency activities with superimposed overriding beta-frequency components consistent with EDB pattern (Fig 2A).

She received IVIG and IV steroids on Days 9-17, and an ovarian teratoma was resected. Her exam continued to worsen and she lost interactivity with the environment. EEG on Day 19 continued to show EDB and poorly formed sleep architecture. There were also bursts of rhythmic notched delta activity followed by 1-second attenuations consistent with seizures (Fig 2B).

She received Rituximab on Days 26 and 43 but her mental status remained unchanged. She also developed severe orofacial dyskinesia. Serial EEGs continued to show EDB pattern, but no sleep architecture or epileptiform abnormalities.

On Day 46, she received her first dose of Bortezomib. Repeat lumbar puncture on Day 65 showed improvement of CSF profile (WBC 3 (93% lymphocyte), RBC 1, glucose 58, protein 28, and NMDA Ab IgG 1:40). Her mental status improved with continued Bortezomib treatment. EEG on Day 69 showed 5-6 Hz theta frequency background intermixed with low voltage beta waves and occasional bursts of alpha frequency waves in posterior head regions (Fig 2C), but no sleep architecture.

Her mental status continued to improve and she was discharged to subacute facility while continuing her Bortezomib infusions as outpatient. She demonstrated good attention and followed all commands at 2-month follow-up.

Conclusions: EEG abnormality correlates with disease severity and is a useful biomarker of disease progression and treatment response in anti-NMDA receptor encephalitis. Extreme delta brush pattern may develop later in the disease course; hence, its absence, especially in earlier stages, should not exclude this diagnosis.

Funding: Please list any funding that was received in support of this abstract.: None.