Brain Swelling in the Asphyxiated Term Newborn: Pathogenesis and Outcome

The role of brain swelling following acute hypoxic-ischemic insult in the genesis of brain injury in the term newborn is controversial. Recent experimental animal studies suggest that it may result from prior irreversible cerebral necrosis and therefore represents a consequence as opposed to a cause of major brain injury. In this study, 32 asphyxiated term newborns were studied during the first week of life with serial intracranial pressure measurements. A total of 26 infants had scans during the first five days of life. Seven patients had two CT scans within this period. These investigations were correlated with outcome at 18 months of age. Seven infants had increased intracranial pressure (> 10 mm Hg) that reached a maximum between 36 and 72 hours of age. Cerebral perfusion pressures remained normal, which makes ongoing ischemic injury unlikely as a cause. The seven patients with increased intracranial pressure had decreased attenuation on CT that was generalized in six infants and patchy in one infant. Of the infants with increased intracranial pressure and severe CT abnormalities, three died and four had severe neurologic sequelae. In seven infants, a second CT scan at three to four days of life demonstrated progression of the decrease in tissue attenuation. Most of the infants with normal intracranial pressure (23/25) had no or had only minor neurologic abnormalities at follow-up. These data suggest that brain swelling is relatively uncommon in the asphyxiated term newborn. The temporal profile of increased intracranial pressure and CT abnormalities, with maximum abnormalities at 36 to 72 hours of age, is most consistent with cerebral necrosis as a cause that, in turn, implies a poor prognosis.