Invited Review: The Brain in Eclampsia

Abstract

The occurrence of a convulsion marks the transition of preeclampsia to eclampsia. Although many women who experience eclamptic convulsions recover without neurologic sequelae including epilepsy, the mortality of eclampsia, much due to cerebral lesions, increases with the number of convulsions. A review of the character of the neurological manifestations of toxemia is followed by proposals for their pathogenesis. The author exposes that the neurologic manifestations of eclampsia are those of hypertensive encephalopathy in previously normotensive young women. Hypertensive encephalopathy occurs if sustained mean arterial blood pressure exceeds the upper limit of autoregulation of cerebral perfusion. Thus, the pathophysiological event which compromises the brain is not a convulsion but rather the point at which a preeclamptic woman's blood pressure exceeds her upper limit of the autoregulation of cerebral perfusion.

A convulsion has been the traditional dividing line between preeclampsia and eclampsia. The danger of convulsions during childbirth was known to ancient Egyptians, Greeks, and Chinese (1,2). Mauriceau (1668) is credited with understanding that delivery usually leads to the cessation of seizures. In 1739 de Sauvages differentiated eclampsia from epilepsy. In 1888, in almost the last treatment of eclampsia in an English-language textbook of neurology for almost one century, Gowers