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Eclampsia's Neurologic Damage May Be Permanent


 

DALLAS — Several years after a pregnancy complicated by eclampsia, significantly more women demonstrate subcortical cerebral white matter lesions on MRI, compared with women with a normotensive pregnancy.

In a study of 103 women, white matter lesions were observed in 16 of 39 (41%) formerly eclamptic women, in 10 of 35 (29%) formerly preeclamptic women, and 5 of 29 (17%) women who had a normotensive pregnancy, lead investigator Annet Aukes and associates reported at the annual meeting of the Society for Maternal-Fetal Medicine.

The average time from index pregnancy was not significantly different between the formerly eclamptic and normotensive groups (7 years vs. 5 years), who were the focus of the analysis. Their mean age was 38 years.

The findings are remarkable because the predominant opinion holds that eclampsia is a one-time event from which women can expect a full clinical recovery.

“We conclude that the paradigm that eclampsia is reversible should be revised,” said Ms. Aukes, an MD/PhD student at the University of Groningen (the Netherlands).

The researchers also observed that the number of eclamptic seizures appeared to be related to the presence and severity of the brain matter lesions. In all, 19 eclamptic women had one grand mal seizure, 10 had two, and 10 had three or more. Women who reported three or more eclamptic seizures were three times more likely to have white matter lesions than were women with no seizures, she said.

The total volume of the lesions was significantly greater among formerly eclamptic women than controls (0.04 mL vs. 0.004 mL).

The neurologic disturbances in eclampsia and preeclampsia are thought to represent a form of posterior reversible encephalopathy syndrome (PRES), which is recognized as a complication in various non-pregnancy-related disorders, including several of iatrogenic or neurotoxic origin, connective tissue disease, and acute glomerulonephritis. It can be reversed by lowering blood pressure and/or discontinuing the offending drug.

In PRES, it is thought that an acute elevation of systemic blood pressure exceeds the upper limit of cerebral autoregulation. This causes forced dilation of cerebral arteries, disruption of the blood-brain barrier, and formation of vasogenic cerebral edema, Ms. Aukes explained.

More recently, it has been hypothesized that when vasogenic edema becomes severe enough, it can result in reduced tissue perfusion and cytotoxic edema because of irreversible ischemic changes that lead to white matter lesions.

The theory is supported by studies, she said, including one in which persistent brain white matter lesions, consistent with the appearance of cerebral tissue loss, were demonstrated in nearly one-fourth of 27 eclamptic women when imaged 6 weeks after delivery (Am. J. Obstet. Gyn. 2004;190:714–20).

A study by Ms. Aukes and associates presented at last year's Society for Maternal-Fetal Medicine meeting demonstrated that formerly eclamptic women reported significantly more disruptions in cognitive function 7.6 years after the index pregnancy than did healthy parous controls (Am. J. Obstet. Gynecol. 2007;197; 365.e1–6).

An audience member asked if baseline imaging data were available on the women who seized to determine if the lesions were predisposing to eclampsia or if they were a result of eclampsia. Ms. Aukes responded that very few women had imaging at the time of their seizures, and thus they had not linked the data. “We're not sure if these lesions were preexisting or occurred during or after the seizures,” she said.

The investigators did not report any conflicts of interest and did not receive funding for the study.

A fluid-attenuated inversion-recovery MRI of a formerly eclamptic patient reveals white matter lesions (arrows). Neuro-Imaging Center of the School of Behavioural and Cognitive Neurosciences in Groningen

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