Differences in vulnerability between the hemispheres in early childhood and adulthood

There are more left hemisphere damaged (LHD) than right hemisphere damaged (RHD) children and adults, if one relies on studies of congenital hemiparesis, as well as on those done on groups with radiologically demonstrated perinatal and postnatal unilateral stroke, hemispherectomy or unilateral epilepsy in childhood or adulthood. The main pathogenetic factor seems to be a hemodynamic one, responsible for insufficient blood supply to the left hemisphere (LH). Since adults show a difference in the same direction as children, the blood supply factor to the left internal carotid artery would seem to be the crucial factor. Around birth, an open ductus arteriosus may play an additional role. The hemodynamic asymmetry does not exclude an intrinsic maturational hemispheric tissue factor, making the left hemisphere more vulnerable than the right to detrimental influences around birth and during the early postnatal period. Immature white matter is especially vulnerable to asphyxia.