EFFECT OF UNILATERAL PERINATAL HYPOXIC-ISCHEMIC BRAIN-DAMAGE ON THE GROSS DEVELOPMENT OF OPPOSITE CEREBRAL HEMISPHERE

The effect of unilateral perinatal cerebral hypoxic-ischemic damage on the gross development of the opposite hemisphere was investigated in immature rats. Eight-day-old rats underwent unilateral common carotid artery ligation followed by exposure to hypoxia (8% oxygen) ranging fr om 1 to 2 h at 37 degrees C. The animals were sacrificed 3 weeks later , and brain damage was assessed histologically, by weighing the cerebr al hemispheres, and by measuring hemispheric cross-sectional area and diameter as well as the thickness of neocortex. There were no signific ant differences in either the size or cortical thickness of the cerebr al hemisphere contralateral to the damaged hemisphere compared to thos e of controls. The results are comparable to the effect of unilateral perinatal hemispheric decortication and hemispherectomy on the growth of the contralateral hemisphere and suggest that: (1) perinatal damage to one cerebral hemisphere does not significantly alter the size of t he other hemisphere, and (2) the contralateral hemisphere may be used as a 'normal' reference in evaluating the extent of atrophy or infarct ion of a cerebral hemisphere damaged earlier by perinatal hypoxia-isch emia.