[Significance of intrapartum asphyxia for the onset of fetal brain damage].

The prevalence of cerebral palsy is around 0.2% and has remained constant during the last 30 years. Retrospective case-control studies do not show a clear correlation between perinatal asphyxia and the development of cerebral palsy. Less than 10% of all cerebral palsy cases show signs of severe asphyxia during labour and delivery as the major pathological and likely cause for the brain damage. Severe cases of birth asphyxia with multiorgan defects and signs of hypoxic-ischaemic encephalopathy have a high mortality and the risk of permanent brain damage is increased by a factor of 10 to 30. Inspite of this, 90% of the survivors show normal development. The association between perinatal asphyxia and neuromotor developmental disturbances does not provide proof of a causal connection. Intrapartal abnormalities of foetal heart rate monitoring are not specific for foetal asphyxia and show only a limited correlation with the apgar and the cord blood pH. Foetal heart rate recording with pathological changes does not imply an elevated risk of later problems with neuromotor development and the widespread use of foetal heart rate monitoring during labour and delivery did not result in a significant reduction in the frequency of cerebral palsy. In addition to malformations, various forms of antinatal pathology like prematurity, intrauterine growth retardation and congenital infections are related to the development of brain damage. In each case of birth asphyxia, additional pathology like congenital infections or malformations in addition to changes in brain structure as a result of asphyxia must be ruled out using specific diagnostic methods like ultrasound, computed tomography and magnetic resonance. Furthermore, a careful documentation of the developmental phases is of fundamental importance for a final evaluation. In otherwise unremarkable deliveries at term, four conditions must be fulfilled to postulate a causal relationship between asphyxia and the development of cerebral palsy: The asphyxia must be severe. During the early neonatal period, clinical symptoms of moderate to severe hypoxic-ischaemic encephalopathy with functional impairment of other organs must be present. The neurological symptoms must be typical for intrapartal asphyxia. Documentation of diagnostic evaluation to rule out other forms of pathology must be complete (21).