Widespread cerebral ischaemia treated with nimodipine in a patient with eclampsia

Posterior Reversible Encephalopathy Syndrome: A Review

Radiologists may be the first to suggest the diagnosis of posterior reversible encephalopathy syndrome (PRES). PRES is associated with many diverse clinical entities, the most common of which are eclampsia, hypertension, and immunosuppressive treatment. Radiologists should be aware of the spectrum of imaging findings in PRES. When promptly recognized and treated, the symptoms and radiological abnormalities can be completely reversed. When unrecognized, patients can progress to ischemia, massive infarction, and death. In this review, we present an overview of the unique signs observed on computed tomography and magnetic resonance images in PRES that can help in the early diagnosis and treatment that is highly effective in this syndrome.

The role of calcium channel blockers in the treatment of women with preeclampsia

Preeclampsia was originally known as a process whereby an unknown “toxin” was responsible for a variety of responses. While this toxin has yet to be determined, many theories have prevailed as to the appropriate therapy for this condition.

Recently, antihypertensive therapy has become increasingly regarded as an important component of the medical management of women with preeclampsia. Initially, the ideal therapy for peripartum acute hypertensive emergencies was felt to be a smooth muscle relaxant and the most commonly prescribed agent was hydralazine. This drug was felt to be beneficial because of its action on vascular smooth muscle, decreasing vasospasm. Outside of the United States diazoxide was also used for this purpose, although this drug has been replaced because of the high incidence of fetal distress. Another agent that was frequently used was α-methyldopa which was initially considered to be the treatment of choice in the treatment of patieats with moderate and severe preeclampsia. Recently, α-methyldopa has been reserved for the outpatient management of gestational hypertension, especially in women with mild preeclampsia or chronic hypertension.

Overlapping features of eclampsia and postpartum angiopathy

INTRODUCTION

Postpartum cerebral angiopathy (PPA) is considered one of a diverse group of rare conditions termed "reversible cerebral vasoconstriction syndromes". Existing literature suggest considerable overlap in the manifestations of eclampsia and PPA.

METHODS

Retrospective case series review of PPA and eclampsia from a single neurosciences intensive care unit patient log identified over a consecutive 18-month period. A MEDLINE search (using OVID) of the English literature from 1950 through October 2008 was also performed.

RESULTS

Four patients who meet the obstetrical criteria for eclampsia and four patients whose clinical and radiographic features were consistent with PPA were identified. Twenty-eight patients with PPA were identified from the literature and showed significant clinical and radiographic overlap without cohort.

CONCLUSION

Given the overlapping clinical, laboratory, and radiographical features of eclampsia and PPA, it is probable they share a similar underlying pathophysiological mechanism and represent different clinical expressions of the same pregnancy-related disorder. The obstetrical definition of eclampsia may be to strict when applied in the neurosciences intensive care unit.

Intérêt du sulfate de magnésium dans la prise en charge de la prééclampsie

In case of eclampsia, and especially in case of preeclampsia, no consensus exist in order to treat or to prevent convulsions by routine use of magnesium sulphate, at least in France. However, a large, multicentre, randomised trial compared the efficacy of magnesium sulphate with diazepam or phenytoin in eclamptic women. In this trial, magnesium sulphate was associated with a significantly lower rate of recurrent seizures and lower rate of maternal death than that observed with other anticonvulsants. The primary objective of magnesium sulphate prophylaxis in women with preeclampsia is to prevent or reduce the rate of eclampsia and complications associated with eclampsia. There are 3 large randomised controlled trials comparing the use of magnesium sulphate to prevent convulsions in patients with severe preeclampsia: the first one was vs phenytoin, the second vs placebo, and the third vs nimodipine. Patients receiving magnesium sulphate presented a significant lower risk of eclampsia than that observed with other comparison groups, probably by decreasing the cerebral perfusion pressure, thus avoiding a cerebral barotrauma. However, several arguments balance a wide use of magnesium sulphate: the prevalence of eclampsia in the Western world is very low, the use of magnesium sulphate does not affect the neonatal morbidity and mortality, and it is associated with a high rate of side effects, sometimes severe, such as respiratory depression. Thus, the benefit to risk ratio has to guide the use of magnesium sulphate and is directly correlated to the prevalence of eclampsia according to the risk of considered group. 1) The rate of seizures in women with mild preeclampsia not receiving magnesium sulphate is very low. Magnesium sulphate may potentially be associated with a higher number of adverse maternal effects. Therefore, the benefit to risk ratio does not support routine use of magnesium sulphate prophylaxis in this group. 2) On the other hand, the higher rate of seizures in women with severe preeclampsia (2.0%), especially in those who have imminent eclampsia, justifies prophylaxis with magnesium sulphate.

A comparison of magnesium sulfate and nimodipine for the prevention of eclampsia

OBJECTIVE

Magnesium sulfate may prevent eclampsia by reducing cerebral vasoconstriction and ischemia. Nimodipine is a calcium-channel blocker with specific cerebral vasodilator activity. Our objective was to determine whether nimodipine is more effective than magnesium sulfate for seizure prophylaxis in women with severe preeclampsia.

METHODS

We conducted an unblinded, multicenter trial in which 1650 women with severe preeclampsia were randomly assigned to receive either nimodipine (60 mg orally every 4 hours) or intravenous magnesium sulfate (given according to the institutional protocol) from enrollment until 24 hours post partum. High blood pressure was controlled with intravenous hydralazine as needed. The primary outcome measure was the development of eclampsia, as defined by a witnessed tonic-clonic seizure.

RESULTS

Demographic and clinical characteristics were similar in the two groups. The women who received nimodipine were more likely to have a seizure than those who received magnesium sulfate (21 of 819 [2.6 percent] vs. 7 of 831 [0.8 percent], P=0.01). The adjusted risk ratio for eclampsia associated with nimodipine, as compared with magnesium sulfate, was 3.2 (95 percent confidence interval, 1.1 to 9.1). The antepartum seizure rates did not differ significantly between groups, but the nimodipine group had a higher rate of postpartum seizures (9 of 819 [1.1 percent] vs. 0 of 831, P=0.01). There were no significant differences in neonatal outcome between the two groups. More women in the magnesium sulfate group than in the nimodipine group needed hydralazine to control blood pressure (54.3 percent vs. 45.7 percent, P<0.001).

CONCLUSIONS

Magnesium sulfate is more effective than nimodipine for prophylaxis against seizures in women with severe preeclampsia.

Diffuse metabolic abnormalities in reversible posterior leukoencephalopathy syndrome

Two cases of reversible posterior leukoencephalopathy syndrome were examined with proton MR spectroscopic imaging. Widespread metabolic abnormalities, consisting of increased choline and creatine levels and mildly decreased N-acetylaspartate, occurred in regions with both normal and abnormal MR imaging appearances. In one case for which proton MR spectroscopic imaging follow-up was available, all metabolite levels had returned to normal by 2 months. Proton MR spectroscopic imaging may be helpful for the diagnosis and investigation of the underlying pathophysiology of reversible posterior leukoencephalopathy syndrome.

The maternal cerebral circulation in pre-eclampsia: investigations using Laplace transform analysis of Doppler waveforms

OBJECTIVE

To compare the maternal cerebral circulation in pre-eclampsia and normal pregnancy using an alternative method of Doppler waveform analysis called the Laplace transform analysis, which provides haemodynamic data additional to standard Doppler indices.

DESIGN

A prospective cross-sectional study.

SETTING

Department of Obstetrics and Gynaecology, Nottingham University Hospital.

SAMPLE

The study involved 17 women in the third trimester of a normal pregnancy, 11 with pregnancy-induced hypertension and 26 with pre-eclampsia.

METHODS

Doppler recordings were obtained from the internal and external carotid and middle cerebral arteries, with the measurements in hypertensive women being carried out before any treatment was given. The waveforms were then subjected to Laplace transform analysis which provides information on vessel wall stiffness and upstream and downstream flow conditions.

MAIN OUTCOME MEASURES

The determination of the Laplace transform analysis parameters, including alpha, the natural frequency of oscillation and real pole, and pulsatility index.

RESULTS

Laplace transform analysis demonstrated a significant increase in vessel wall stiffness in all the arteries in hypertensive pregnancies, but this was more marked in pre-eclampsia. The data were also consistent with, but do not prove, increased downstream resistance in the middle cerebral artery in women with pre-eclampsia but not in those with pregnancy-induced hypertension.

CONCLUSIONS

The Laplace transform analysis of Doppler waveforms yields important physiological information concerning the cerebral circulation in pre-eclampsia, not detected using conventional Doppler indices. The results suggest that both pre-eclampsia and pregnancy-induced hypertension are associated with increased cerebral arterial wall stiffness and that, in addition, there may be cerebral vasoconstriction in pre-eclampsia.

Change in estimated cerebral perfusion pressure after treatment with nimodipine or magnesium sulfate in patients with preeclampsia

OBJECTIVE

Data are accumulating to suggest that cerebral perfusion pressure may be either abnormally high or low in preeclampsia and eclampsia. Little is known of the cerebral perfusion pressure effects of magnesium sulfate or nimodipine. Our objective in this study was to compare the change in cerebral perfusion pressure in patients with severe preeclampsia randomly selected to receive nimodipine or magnesium sulfate.

STUDY DESIGN

Patients with severe preeclampsia were randomly selected to receive magnesium sulfate (6 g bolus and 2 g/hr intravenous infusion) or nimodipine (60 mg taken orally every 4 hours). Transcranial Doppler ultrasonography was used to measure flow velocities in the right and left middle cerebral arteries, and the results were averaged. Measurements were obtained before treatment (baseline) and 30 minutes after the magnesium sulfate bolus was completely infused or 30 minutes after the nimodipine was ingested. Studies were performed before any other intervention. The person performing the ultrasonography was unaware of the patient's group assignment. Estimated cerebral perfusion pressure was calculated with the following formula: Estimated cerebral perfusion pressure = Velocity(mean) x [(Blood pressure(mean ) - Blood pressure(diastolic ))/(Velocity(mean) - Velocity(diastolic ))]. The difference between estimated cerebral perfusion pressure at baseline and after treatment was compared between the 2 groups by means of the Mann-Whitney rank sum test.

RESULTS

Nine patients were randomly selected to receive nimodipine and 12 to receive magnesium sulfate. Patient demographics and severity of condition were not significantly different between the 2 groups. The change in estimated cerebral perfusion pressure was significantly different between the groups. Estimated cerebral perfusion pressure increased after nimodipine use and decreased after magnesium sulfate use.

CONCLUSION

Shortly after administration to patients with severe preeclampsia, nimodipine resulted in increased cerebral perfusion pressure in comparison with magnesium sulfate.

Prevention of eclampsia

Eclampsia continues to be a major cause of maternal morbidity and mortality rates, especially in underdeveloped nations. Our data indicate that eclampsia may represent the end stage of at least two very different pathophysiological pathways: one in which cerebral perfusion is low because of vasospasm and another in which cerebral perfusion is increased because of abnormal autoregulation and a failure of the normal protective mechanisms. Magnesium sulfate has been extensively used in the management and prevention of eclamptic seizures in the United States and has been recently shown to be superior to both diphenylhydantoin and diazepam. We have shown that magnesium sulfate is a potent vasorelaxant and that its action may depend on improving cerebral perfusion. Nimodipine, a calcium channel blocker with selective cerebrovascular effect, is currently under investigation in severe preeclampsia. The data show that it is as effective as magnesium sulfate in preventing eclampsia, with less maternal and fetal side effects. Magnesium sulfate and nimodipine have opposite effects on the estimated cerebral perfusion pressure as determined with the Doppler ultrasound. We speculate that the estimated cerebral perfusion pressure may be used to determine the type of cerebrovascular abnormality and the most appropriate treatment in each individual patient with preeclampsia.

The effect of nifedipine and methyldopa on maternal cerebral circulation

OBJECTIVE

To study how the treatment of severe gestational hypertension affects maternal middle cerebral artery velocimetry.

DESIGN

Prospective, clinical, descriptive study.

SETTING

John Radcliffe Maternity Hospital, Oxford, England.

PARTICIPANTS

Pregnant and puerperal women who required acute or chronic antihypertensive treatment with nifedipine (n = 46) or methyldopa (n = 26), respectively.

METHODS

Transcranial Doppler ultrasound examinations of maternal middle cerebral arteries were performed before and 45 min after nifedipine; and before and 48 hours after the onset of methyldopa therapy. Blood pressure and heart rate were also recorded.

MAIN OUTCOME MEASURES

Clinical and transcranial Doppler changes induced by the antihypertensive medication.

RESULTS

Blood pressure and middle cerebral artery velocities decreased significantly following both short- and long-acting antihypertensive therapy. Nifedipine-induced changes were more pronounced and uniform than those found after methyldopa (16.7% and 6.4% decrease in middle cerebral artery mean velocity, respectively). The middle cerebral artery mean velocity decrease was independent of changes in the blood pressure or heart rate.

CONCLUSIONS

Maternal cerebral haemodynamics are influenced by antihypertensive treatment. The reduction of middle cerebral artery flow velocities following administration of nifedipine and methyldopa may suggest that cerebral vasodilatation is occurring, which is consistent with the concept that cerebral vasospasm is present in women with pre-eclampsia. The cerebral vasodilatation could result from a direct effect of the medication on the arteries in question.

The haemodynamic and respiratory effects of intravenous nimodipine used in the treatment of eclampsia

OBJECTIVE

To establish the antihypertensive properties of intravenous nimodipine used to treat eclamptic patients. To assess the effects of intravenous nimodipine on oxygen delivery and consumption.

DESIGN

A prospective observational study.

SETTING

The Maternity Centre Obstetric Intensive Care Unit, Groote Schuur Hospital.

PARTICIPANTS

Four unselected patients presenting with proteinuric hypertension and seizures.

METHODS

Haemodynamic observations were obtained by a radial artery catheter and right heart catheterisation with a pulmonary artery flow directed thermodilution catheter. Observations were obtained prior to and after the administration of nimodipine.

RESULTS

A significant reduction in mean arterial pressure occurred in all patients after administration of nimodipine. This was due to a significant reduction in systemic vascular resistance. Neither oxygen delivery to the tissues nor peripheral oxygen consumption changed significantly during nimodipine infusion. No adverse effects related to the use of nimodipine were documented.

CONCLUSIONS

Nimodipine is an effective vasodilator. There may be a role for nimodipine as a single agent for the management of eclampsia.

The role of serotonin in preeclamptic hypertension. A review and case report

Generalized arteriolar vasospasm and subsequent damage to vascular endothelium are fundamental to the development of preeclampsia. A possible mechanism underlying this involves increased deportation of trophoblast cells into maternal venous circulation with 5-hydroxytryptamine (serotonin, 5-HT) release as a consequence of platelet aggregation onto these fragments. Ketanserin, a 5-HT(2) receptor blocker, has been used successfully to treat preeclampsia. An examination of the therapeutic role of ketanserin indicates that there should now be a much more detailed assessment of serotonin antagonists in the treatment and prophylaxis of preeclampsia and eclampsia.

The feasibility of a control population for a randomized control trial of seizure prophylaxis in the hypertensive disorders of pregnancy

OBJECTIVE

To document the feasibility of a control population for a randomized controlled trial, we report our experience in managing hypertensive pregnancies without seizure prophylaxis.

STUDY DESIGN

An 8-year cross-sectional study in one institution was performed of all hypertensive patients.

RESULTS

Of 467 patients with preeclampsia or superimposed preeclampsia managed without seizure prophylaxis, 18 had seizure activity, 3.9% (95% confidence interval 2.3% to 6.0%). There was no seizure-related maternal mortality or major morbidity, and the perinatal mortality rate after 28 gestational weeks was the same in patients with or without seizures. By logistic regression seizures were 17.4 times more likely in preeclampsia and 8.1 times more likely in chronic hypertension with superimposed preeclampsia, compared with gestational or chronic hypertension alone.

CONCLUSION

The rate of seizures in patients with preeclampsia or superimposed preeclampsia managed without seizure prophylaxis was low and unassociated with an increase in maternal or perinatal mortality. A control arm is feasible in a randomized, controlled trial to address the issue of whether antiseizure medication can prevent eclampsia.

Electroencephalogram and computerised cerebral tomography findings in eclampsia

OBJECTIVE

To define more clearly the neuropathophysiology of eclampsia.

DESIGN

A prospective study relating to computerised cerebral tomography (CAT) scan and electroencephalogram (EEG) findings in eclampsia.

SETTING

A large referral centre in a developing society.

SUBJECTS

Thirty-two women with eclampsia.

MAIN OUTCOME MEASURES

Abnormalities in EEG and CAT scan findings.

RESULTS

Approximately 45% of the women studied had CAT scan abnormalities, while 90% had EEG abnormalities. A burst suppression pattern on EEG examination was found in four women suggesting a temporary dissolution of cerebral function to the midbrain level as the cause of seizures.

CONCLUSIONS

EEGs are probably more sensitive than CAT scans in detecting the extent of the pathology in the brain in women with eclampsia.

The use of nimodipine in a patient with eclampsia: color flow Doppler demonstration of retinal artery relaxation

Color flow Doppler ultrasonography was used to demonstrate a significant and sustained reduction in the central retinal artery pulsatility index after administration of the calcium antagonist nimodipine to a patient with eclampsia. Nimodipine is an effective cerebral vasodilator and may be useful in the management of eclamptic patients with severe vasospasm.