Maternal cerebral circulation in normal and abnormal pregnancies

Abnormal pregnancies are usually associated with an impairment of maternal cerebral circulation which is mainly a consequence of generalized vasospasm and cerebral edema. The pathogenesis of vasospasm has still been a matter of controversy. The aim of this study was to evaluate maternal cerebral blood flow velocity (CBFV) changes in normal and abnormal pregnancies, and to correlate CBFV findings with the severity of symptoms in abnormal pregnancies.

A group of 40 gravidas (aged between 25 and 32 years) with pre-eclampsia were analyzed by Transcranial Doppler (TCD), Color Doppler Flow Imaging of carotid arteries and Transcranial Color Coded System once a week, starting from 32nd week of pregnancy and followed 2 months after delivery. The study was performed from the January 1996 to June 1996.

The results showed 70% of abnormal pregnancies to have impaired TCD findings, mostly increased CBFV. The degree of toxemia measured by Goecke's index significantly correlated with abnormal CBFV Nine gravidas with increased CBFV on the first examination developed vasospasm during 34 to 36 weeks of gravidity. No statistically significant difference of the M1 segment of MCA diameters was found between normal (3.8 +/- 0.7 mm) and abnormal pregnancies (4.1 +/- 0.9 mm).

The increase in the maternal CBFV was the most frequent observation in abnormal pregnancies. It was progressive during late pregnancy, when vasospasm may develop, although the presence of vasospasm is still the matter of controversy. The most important observation was that significant changes in CBFV preceded neurologic symptoms, emphasizing the predictive role of TCD in abnormal pregnancies.