Cortical vision, MRI, and developmental outcome in preterm infants

Abstract

Objective: We tested two measures of visual cortical function in the first year of life as early markers for functionally significant brain damage in infants born preterm: orientation-reversal visual event-related potentials (OR-VERP), and a behavioural test of cortically controlled visual attention - fixation shifts under competition (FS). We examine how these measures relate to (1) perinatal brain insults identified from MRI , and (2) later neurodevelopmental status.

Patients and methods: Following neonatal and term age equivalent MRI, 26 preterm infants, (< 32 weeks GA, mean 28.1 weeks) had the OR-VERP and FS tests before 12 months post-term age, and a neurodevelopmental assessment (Griffiths Scales) at 2 years. MRI images, examined for parenchymal lesions, intraventricular haemorrhage, ventricular dilatation and Diffuse Excessive High Signal Intensity (DEHSI) were classified into three categories of severity. Cortical visual test results were compared across these categories and examined as predictors of developmental status at 2 years.

Results: 26 infants (mean GA at birth 28.1 weeks) were studied. 15/25 infants showed significant OR-VERP responses. 11/26 had normal FS performance. On both tests, the proportion of infants meeting these criteria decreased significantly with MRI severity. As predictors of Griffiths developmental quotient ¡Ü80, the FS test had sensitivity 100%, specificity 61%, and positive and negative predictive values of 50% and 100% respectively; corresponding figures for OR-VERP were 86%, 63%, 50% and 91%.

Conclusions: Visual cortical tests can provide early indicators of the functional impact of perinatal brain damage in the preterm infant.