Abstracts

Rationale: Extreme delta brush (EDB) is a rare pattern on EEG which has been reported in adults and children with anti-NMDA receptor autoimmune encephalitis. We report a case of Subacute Sclerosing Panencephalitis (SSPE) without periodic high-amplitude complexes in which extreme delta brush was identified on electroencephalography (EEG). Methods: A retrospective chart review was performed for one patient receiving care at this author’s institution. Clinical history, demographic, MRI, EEG, and laboratory data was obtained according to IRB-approved protocol. Results: A 26 year old pregnant woman at 36 weeks’ gestation was admitted to the inpatient neurology service with subacute progressive neurologic decline. At 11 months of age while living in Mexico, the patient developed a rash and encephalitis from measles infection which required hospitalization. At age 14, she experienced a generalized convulsive seizure and she was managed with anti-epileptic medication. Brain MRI revealed multiple non-enhancing foci of T2/FLAIR hyperintensity in the subcortical white matter of the left temporal, bilateral frontal, and bilateral occipital lobes and diffuse cerebral, cerebellar, and brainstem atrophy. Routine EEG at that time was remarkable for re-current, pseudo-periodic one-second bursts of delta, theta, and sharp waves most prominent in the centrocephalic region. Anti-epileptic therapy was maintained until two years prior to the current presentation after the patient remained seizure free for several years.Two weeks before admission, she developed progressive memory impairment, anhedonia, headache, and abnormal limb movements. Contrast-enhanced MRI of the brain revealed increased T2/FLAIR white matter hyperintensities in bilateral frontal, temporal, parietal, and occipital lobes compared to prior imaging. There was bilateral thalamic swelling with diffusion restriction. Rubeola IgG and IgM antibodies were present in her CSF and elevated CSF globulin levels, consistent with a diagnosis of SSPE.Video EEG demonstrated moderate generalized background slowing and periodic posterior-predominant delta activity with overlying low amplitude 20-30 Hz fast activity most consistent with EDB (Figure 1). No epileptiform activity was present. No sedative medication had been administered for 72 hours prior to the EEG. The patient developed progressive neurologic decline and she was discharged to a long-term care facility in a comatose state. Conclusions: In this case, we describe a patient with SSPE with EDB on EEG; the classic periodic high-amplitude complexes typically associated with SSPE were absent. These findings suggest that, in the appropriate clinical setting, alternative diagnoses to anti-NMDAR encephalitis should be considered when EDB is present on the EEG. Funding: None.