[Anomalies in brain haemodynamics in pre-eclamptic expectant mothers]

Transcranial Doppler (TCD) is being used more and more frequently in the study of brain haemodynamics in pre-eclampsia/eclampsia. It has received less attention in the puerperium of these patients.

The aim of our study was to compare pre-eclamptic (PE) and normotensive (NT) patients at the end of gestation, using a Doppler velocimeter, and also to compare the results from PE women in two consecutive periods of time: at the end of gestation and in early puerperium (EP).

TCD was performed with bilateral evaluation of the anterior, middle and posterior cerebral arteries (ACA, MCA and PCA, respectively). Average speed (AS) and the pulsatility index (PI) were used as Doppler parameters. Arterial blood pressure (BP) and haematocrit were also measured. The AS, PI, average BP (ABP) and haematocrit were used as variables in the statistical analysis. At the end of gestation (33 weeks to full term) we compared the average values of these variables in PE (n=38) against those of NT (n=44). We also compared the results obtained for PE (n=30) in two consecutive periods: at the end of gestation and EP (the first five days following childbirth).

At the end of gestation, AS were significantly higher in the PE than in the NT in all the arteries that were examined. The ABP was higher in the first group but there was no significant correlation between ABP and AS. PI were lower in the first group, with statistical signification in four of the six arteries. The AS rose significantly in the EP of the PE women, in spite of the existence of a drop in the ABP. Conversely, the PI remained unaltered.

A pattern of high AS and low PI was found in PE women at the end of gestation and may be due to a primary failure of the brain's capacity to regulate itself. Anomalies in the TCD increased in the EP, despite a drop in the ABP, and this could account for the predominance of the neurological symptoms that are reported in the later forms of the syndrome.