A bootstrap approach to testing for an association between bursts in the neonatal EEG and changes in cerebral blood flow

In normal premature neonates, a pattern of EEG, known as trace discontinu, is common, which contains bursts of relatively high voltage, in an otherwise lower voltage background. The current work investigates whether these bursts are associated with changes in the velocity of blood, measured by transcranial Doppler ultrasound in the middle cerebral artery. A measure of consistency in the response from repeated bursts is proposed, and in order to test its significance, a bootstrap method was devised. With this method signals that are interrupted by ´missing samples´, where segments of the signal are lost due to excessive noise or artifact (as was the case in our recordings), can also be analysed. Monte Carlo simulation studies demonstrate the potential of this approach. In tests on 12 recordings from premature babies it was found that 3 had significantly consistent responses, with a peak in cerebral blood flow velocity some 5-12 seconds after the onset of the bursts. Overall, the results suggest that there is an association between bursts and blood-flow, at least in some subjects, but the causal mechanisms require further studies.