Background: Zika virus infection during pregnancy is linked to birth defects, most notably, microcephaly, which in its turn, is associated with neurodevelopmental delays. Objective: The goal of the study is to propose a method for severity classification of congenital microcephaly based on neuroradiological findings of MRI scans, and to investigate the association of severity with neuropsychomotor developmental scores. We also propose a semiautomated method for MRI-based severity classification of microcephaly. Methods: Cross-sectional investigation of 42 infants born with congenital Zika infection. Bayley-III developmental evaluations and MRI scans were carried out at ages 13-39 months (mean: 24.8, SD: 5.8). The severity score was generated based on neuroradiologist evaluations of brain malformations. Next, we established a distribution of Zika virusmicrocephaly severity score into mild, moderate, and severe and investigated the association of severity with neuropsychomotor developmental scores. Finally, we propose a simplified semi-automated procedure for estimating the severity score, based only on volumetric measures. Results: Results showed a correlation of r = 0.89 (p < 0.001) between the Zika virus-microcephaly severity score and the semi-automated method. The trimester of infection did not correlate with the semi-automated method. Neuropsychomotor development correlated with the severity classification based on radiological readings and with the semi-automated method; the more severe the imaging scores, the lower neuropsychomotor developmental scores. Conclusion: The severity classification methods may be used to evaluate severity of microcephaly and possible association with developmental consequences. The semi-automated methods thus may be an alternative for prediction of severity of microcephaly using only one MRI sequence.

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Objectives: We propose and evaluate a system for assessing severity of ZikV-related microcephaly brain abnormalities called RaRe (Radiological Reading score). The system is a combination of neuroradiologist evaluation scores; we also propose and evaluate its semi-automated version, which is generated from MRI indices. Design: We carried out a cross-sectional study with retrospective data collection at birth and 13-39 months; data collection includes radiologists evaluation of MRI images and a semi-automated system for analyzing MRI images from ZikV-related microcephaly patients; we also evaluated the association of severity and RaRe scores with developmental outcomes. Setting: Brain Institute of Rio Grande do Sul and Memorial Hospital Arthur Ramos, both in Brazil. Participants: 42 infants with ZikV-related congenital microcephaly (age at second evaluation M = 24.83 months; SD = 5.82). Mothers were infected by Zika Virus during pregnancy and were symptomatic or asymptomatic. Main outcome measures: Clinical and radiological outcomes (blindly reviewed); severity classification system (semi-automated - RaRe-Auto or based on neuroradiological evaluation - RaRe-Clin) and association with developmental outcomes (Bayley-III scales). Results: RaRe-Clin positively correlated with RaRe-Auto (r = 0.892; p < 0.001). Severity negatively associated with neurodevelopment scores assessed by Bayley-III scales in all three domains: cognition, language and motor skills. There was no association between trimester of infection and head circumference at birth (r = 0.160; p = 0.338) but there was an association between trimester of infection and RaRe-Clin (r = -0.355; p = 0.029). Conclusions: The clinical and semi-automated RaRe scores predicted Bayley scores. RaRe-Clin and RaRe-Auto can predict the trimester of infection and severity of outcomes and should be investigated in their further application with other congenital and infection-related brain abnormalities.