Brain lesions in preterms: origin, consequences and compensation.

Abstract

Twenty-nine high-risk preterm born children, from a cohort with cerebral blood flow (CBF) measurements in the first 2 d of life, were examined prospectively at the age of 5.5-7 y neurologically, neuropsychologically and by magnetic resonance imaging (MRI). They were compared to 57 control children in terms of neurology and neuropsychology. Abnormal MRI was found in 19 children. 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 MRI abnormalities were mainly periventricular lesions (n = 19), especially periventricular leucomalacia (PVL, n = 17). Three of the very preterm children had severe cerebellar atrophy in addition to relatively mild periventricular abnormalities. MRI showed specific morphological correlates for the major disabilities, e.g. spastic CP (involvement of motor tracts), mental retardation (bilateral extensive white matter reduction or cerebellar atrophy) and severe visual impairment (severe optic radiation involvement). A morphological correlate for minor disabilities, i.e. functional variations in motor performance or intelligence, was not found, with the exception that symptoms of attention deficit hyperactivity disorder were related to mild MRI abnormalities. This could mean that with respect to 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; other, more chronic pathogenetic factors, not detectable by MRI alone, may play a role.