Brain lesions in preterms: origin, consequences and compensation

Twenty-nine high-risk preterm born children, from a cohort with cerebral bl ood flow (CBF) measurements in the first 2d of life, were examined prospect ively at the age of 5.5-7 y neurologically, neuropsychologically and by mag netic resonance imaging (MRI). They were compared to 57 control children in terms of neurology and neuropsychology. Abnormal MRT was found in 19 child ren. Low oxygen delivery to the brain was found in 63% of them, in contrast to 12.5% in those with normal MRI, indicating neonatal hypoxia-ischemia as an important factor. The MRT abnormalities were mainly periventricular les ions (n = 19), especially periventricular leucomalacia (PVL, n=17). Three o f the very preterm children had severe cerebellar atrophy in addition to re latively mild periventricular abnormalities. MRI showed specific morphologi cal correlates for the major disabilities, e.g. spastic CP (involvement of motor tracts), mental retardation (bilateral extensive white matter reducti on or cerebellar atrophy) and severe visual impairment (severe optic radiat ion involvement). A morphological correlate for minor disabilities, i.e. fu nctional variations in motor performance or intelligence, was not found, wi th the exception that symptoms of attention deficit hyperactivity disorder were related to mild MRI abnormalities. This could mean that with respect t o cognitive functions, mild or unilateral periventricular MRI lesions could be compensated. However, as among preterms without mental retardation (n = 19), IQ was generally and significantly lower than in the control group; o ther, more chronic pathogenetic factors, not detectable by MRI alone, may p lay a role.