Sleep EEG of Microcephaly in Zika Outbreak.

Microcephaly (MC), previously considered rare, is now a health emergency of international concern because of the devastating Zika virus pandemic outbreak of 2015. The authors describe the electroencephalogram (EEG) findings in sleep EEG of epileptic children who were born with microcephaly in areas of Brazil with active Zika virus transmission between 2014 and 2017. The authors reviewed EEGs from 23 children. Nine were females (39.2%), and the age distribution varied from 4 to 48 months. MC was associated with mother positive serology to toxoplasmosis (toxo), rubella (rub), herpes, and dengue (1 case); toxo (1 case); chikungunya virus (CHIKV) (1 case); syphilis (1 case); and Zika virus (ZIKV) (10 cases). In addition, 1 case was associated with perinatal hypoxia and causes of 9 cases remain unknown. The main background EEG abnormality was diffuse slowing (10 cases), followed by classic (3 cases) and modified (5 cases) hypsarrhythmia. A distinct EEG pattern was seen in ZIKV (5 cases), toxo (2 cases), and undetermined cause (1 case). It was characterized by runs of frontocentrotemporal 4.5-13 Hz activity (7 cases) or diffuse and bilateral runs of 18-24 Hz (1 case). In ZIKV, this rhythmic activity was associated with hypsarrhythmia or slow background. Further studies are necessary to determine if this association is suggestive of ZIKV infection. The authors believe that EEG should be included in the investigation of all newly diagnosed congenital MC, especially those occurring in areas of autochthonous transmission of ZIKV.

Extreme Spindles and Leukoencephalopathy after Acute Lymphoblastic Leukemia Treatment: An Undescribed Association.

We report a case of a child whose EEG demonstrated extreme spindles (ES) after acute lymphoblastic leukemia treatment. This finding has not been reported previously. In 1962, Gibbs and Gibbs described the ES EEG pattern due to its high amplitude (200 to 400 µV). ES are a rare spindle variant that is found in EEGs of 0.05% of normal children (average age, 3 years, with a range of 1 to 12 years), and are even rarer after 11 years. Moreover due to changes in the white matter of the frontal lobe, ES have been associated with such conditions as cerebral palsy and mental retardation, residual brain damage, undefined infections, infantile neuroaxonal dystrophy, Menkes' kinky-hair syndrome, congenital muscular dystrophy, hydrocephalus, porencephaly, epilepsy, progressive cerebellar degeneration, and mycoplasma encephalitis. Methotrexate has a notably toxic effect on the central nervous system, with leukoencephalopathy being the most common form. In our case, frontocentral ES were associated with hyperintense lesions in the white matter of the frontal lobe. Lesional deafferentation can be the substrate for an almost continuous ES, since both initiation and termination of spindle oscillations are thought to originate in thalamocortical neurons. Thus, we postulate that in some cases a partial functional cortical differentiation could generate ES.