Hypoxic ischaemic encephalopathy: correlation between ultrasound and computed tomography.

Hypoxic ischaemic encephalopathy (HIE) is a major cause of motor and mental retardation. There ist no doubt that the haemorrhagic form of HIE can be detected by cerebral sonography, but it is of great interest to recognize non-haemorrhagic HIE as well. We demonstrate the follow-up of three patients with different types of non-haemorrhagic HIE: Periventricular leukomalacia in a critical ill premature infant 35 weeks gestational age, multicystic encephalopathy in a term newborn with severe perinatal asphyxia and circumscript ischaemic leukomalacia in a five month old infant with near miss event for sudden infant death. Correlation between ultrasound and computed tomography proved that non-haemorrhagic HIE produces global or circumscript high echogenicity in the first week after the hypoxic event whereas computed tomography shows pathologic hypodensity in the same areas. Cerebral sonography is a very helpful and harmless method for the difficult diagnosis HIE. In the case of periventricular leukomalacia, CT scan gives no further information and can be avoided. Concerning HIE of term newborns and small infants, CT scan remains necessary, to evaluate the extension of cerebral injury.