Sleep EEG patterns in infants with congenital Zika virus syndrome.

Objectives: To describe sleep EEG patterns of neonates, and infants with microcephaly due to congenital Zika virus (ZikV) syndrome.

Methods: A descriptive case series of EEGs performed in a cohort of neonates with microcephaly monitored from October 2015 to February 2016 at a University Hospital in Northeast Brazil. Infants were investigated following an established protocol that includes EEG, neuroimaging studies, PCR and specific antibodies for ZikV detection.

Results: EEGs (n=37) from 37 infants were reviewed. Age at investigation varied from 1 to 5months (mean=2.6). Diffuse low voltage (n=7), background asymmetry (n=6) and modified hypsarrhythmia with or without burst-suppression (n=11), were the main background abnormalities identified. Interictal EEG abnormalities were identified in 23 recordings (62%) and localized as focal frontal (n=8) or occipital (n=2) spikes/sharp, multifocal spikes/sharp waves (n=13). Electrographic seizures without clinical manifestation were identified in 4 recordings and characterized as focal pseudo rhythmic pattern. Further findings were focal high amplitude slow waves that were registered in the frontal (n=3) or occipital (n=1) regions.

Conclusions: Different types of EEG abnormalities were encountered with a predominance of interictal epileptogenic activity and hypsarrhythmia.

Significance: Sleep EEGs in congenital Zika virus syndrome are consistently abnormal even in infants who have not yet developed epilepsy.