Maternal transcranial Doppler in pre-eclampsia and eclampsia

Assessment of transcranial Doppler indices after MgSO4 administration in severe preeclamptic women with neurologic symptoms

PURPOSE

To investigate the effect of intravenous MgSO4 on maternal cerebral hemodynamics as well as the association between altered Doppler indices of the ophthalmic arteries and ocular lesions in patients with preeclampsia.

METHODS

After each of the 15 included patients was diagnosed with preeclampsia, MgSO4 was infused followed by transcranial Doppler tests of the indices of the ophthalmic, anterior, middle, posterior cerebral, vertebral, and basilar arteries, followed by a second MgSO4 infusion. The peak, mean, diastolic velocity, and pulsatile and resistance indices of each artery were automatically measured during testing. Based on the emergent data, the cerebral perfusion pressure, resistance-area product, and cerebral flow index were calculated.

RESULTS

The cerebral perfusion pressure of the posterior cerebral arteries significantly decreased following the infusion of MgSO4 (p < 0.05). Before the infusion of MgSO4, cerebral perfusion pressure and cerebral flow index of the ophthalmic arteries were significantly increased (p < 0.05) in the preeclamptic pregnant patients with ocular lesions compared those without ocular lesions. After the infusion of MgSO4, the cerebral perfusion pressure and cerebral flow index of both ophthalmic arteries were slightly decreased, but the difference was not significant.

CONCLUSIONS

Altered Doppler indices following the infusion of MgSO4 suggest significant changes in the hemodynamics of the posterior cerebral and ophthalmic arteries that are particularly related to the neurological signs and symptoms of women with preeclampsia. These findings may improve the understanding of the mechanism of the cerebral complications of preeclampsia. Advancing comprehension of these underlying mechanisms is postulated to play a pivotal role in the mitigation of hypertensive encephalopathy associated with preeclampsia.

Cerebral hemodynamics and vasoconstriction in preeclampsia: From diagnosis to resolution

OBJECTIVES

To evaluate maternal cerebral hemodynamics in patients with preeclampsia (PE) from diagnosis to clinical resolution using transcranial Doppler (TCD) and compare these findings with those of healthy pregnant women. Furthermore, we sought to describe the prevalence of vasoconstriction (VC) and related clinical parameters in PE.

STUDY DESIGN

Case-control study including consecutive patients with PE at diagnosis and healthy pregnant women at week 36 of pregnancy. We prospectively collected clinical and neuroimaging data. TCD was repeated at inclusion and on days 1, 7, and 30 postpartum.

MAIN OUTCOME MEASURES

Evolution of intracranial arteries hemodynamics (mean velocities (MV), resistance index). VC diagnosis and related features are described.

RESULTS

A total of 165 patients (80 with PE) underwent 467 TCD procedures. Patients with PE presented higher MAP. Intracranial arteries MV were significantly higher in patients with PE (at diagnosis and days 1 and 7 postpartum) but were normalized by day 30, without correlation with MAP evolution or treatment. VC was present in 32.5% of patients with PE (p < 0.001) and was mainly mild according to the Lindegaard index. Severe PE was associated with VC (50.0% vs. 22.6%; odds ratio 3.484; 95% confidence interval 1.425-8.520; p = 0.014). No other independent risk factors for reversible VC were identified.

CONCLUSIONS

Patients with PE presented significantly higher MV in the anterior circulation compared to healthy controls, which worsened by day 7 and reverted by day 30 after delivery. VC was present in one-third of PE but was mainly mild and asymptomatic. Severe PE was associated with VC development.

Transcranial Doppler role in prediction of post-dural puncture headache in parturients undergoing elective cesarean section: prospective observational study

PURPOSE

Post-dural puncture headache (PDPH) may be resulted from significant changes in cerebral blood flow, which could be visualized by Transcranial Doppler (TCD). This study was performed to investigate if TCD can be used to predict the occurrence of PDPH in high-risk patients.

METHODS

This prospective observational study was conducted on ninety ASA I and II pregnant females undergoing elective cesarean section (CS) under spinal anesthesia. TCD was performed to all patients within 24 h before the operation, at 24 h and 48 h in the post-operative period to measure mean velocity (MV) and Gosling pulsatility index (PI) in the right middle cerebral artery. For 5 days postoperatively, all patients were assessed and the PDPH patients were identified, their pre- and post-puncture TCD measurements were compared with the corresponding measurements of PDPH-free patients and ROC analysis was done to evaluate the predictive value of TCD parameters.

RESULTS

17 patients (18.8%) developed PDPH. PDPH group was significantly higher regarding MV and significantly lower with regard to PI at all times except for the pre-spinal PI. The MV values in all patients showed statistical significant increase within the first 48 h after CS as compared with those before delivery. In PDPH group there was high statistical significant decrease in PI values at 24 h and 48 h compared to the pre-puncture values. The pre-puncture MV was the parameter of the best accuracy for predicting PDPH with a cutoff of MV > 68.4 cm/s and the post-puncture PI at 24 h was the best predictive of PDPH with a cutoff value of < 0.75.

CONCLUSION

TCD might prove a useful tool in predicting PDPH suggesting that higher pre-puncture MV with a cutoff value > 68.4 cm/s and post-puncture lower PI at 24 h with a cutoff < 0.75 are the best predictive parameters.

TRIAL REGISTRATION

This clinical trial was registered with ClinicalTrials.gov (NCT03464253).

Effects of perinatal blood pressure on maternal brain functional connectivity

Perinatal hypertensive disorder including pre-eclampsia is a systemic syndrome that occurs in 3–5% of pregnant women. It can result in various degrees of brain damage. A recent study suggested that even gestational hypertension without proteinuria can cause cardiovascular or cognitive impairments later in life. We hypothesized that perinatal hypertension affects the brain functional connectivity (FC) regardless of the clinical manifestation of brain functional impairment. In the present study, we analyzed regional global connectivity (rGC) strength (mean cross-correlation coefficient between a brain region and all other regions) using resting-state functional magnetic resonance imaging to clarify brain FC changes associated with perinatal blood pressure using data from 16 women with a normal pregnancy and 21 pregnant women with pre-eclampsia. The rGC values in the bilateral orbitofrontal gyri were negatively correlated with diastolic blood pressure (dBP), which could not be explained by other pre-eclampsia symptoms. The strength of FC seeding at the left orbitofrontal gyrus was negatively correlated with dBP in the anterior cingulate gyri and right middle frontal gyrus. These results suggest that dBP elevation during pregnancy can affect the brain FC. Since FC is known to be associated with various brain functions and diseases, our findings are important for elucidating the neural correlate of cognitive impairments related to hypertension in pregnancy.

Cerebrovascular Reactivity and Vascular Activation in Postmenopausal Women With Histories of Preeclampsia

Cerebrovascular reactivity (CVR) is reduced in patients with cognitive decline. Women with a history of preeclampsia are at increased risk for cognitive decline. This study examined an association between pregnancy history and CVR using a subgroup of 40 age- and parity-matched pairs of women having histories of preeclampsia (n=27) or normotensive pregnancy (n=29) and the association of activated blood elements with CVR. Middle cerebral artery velocity was measured by Doppler ultrasound before and during hypercapnia to assess CVR. Thirty-eight parameters of blood cellular elements, microvesicles, and cell-cell interactions measured in venous blood were assessed for association with CVR using principal component analysis. Middle cerebral artery velocity was lower in the preeclampsia compared with the normotensive group at baseline (63±4 versus 73±3 cm/s; P=0.047) and during hypercapnia (P=0.013-0.056). CVR was significantly lower in the preeclampsia compared with the normotensive group (2.1±1.3 versus 2.9±1.1 cm·s·mm Hg; P=0.009). Globally, the association of the 7 identified principal components with preeclampsia (P=0.107) and with baseline middle cerebral artery velocity (P=0.067) did not reach statistical significance. The interaction between pregnancy history and principal components with respect to CVR (P=0.084) was driven by a nominally significant interaction between preeclampsia and the individual principal component defined by blood elements, platelet aggregation, and interactions of platelets with monocytes and granulocytes (P=0.008). These results suggest that having a history of preeclampsia negatively affects the cerebral circulation years beyond the pregnancy and that this effect was associated with activated blood elements.

Assessment of maternal cerebral blood flow velocity by transcranial Doppler ultrasound before delivery and in the early postpartum period

OBJECTIVE

This prospective observational study aimed to identify the effects of labor on cerebral hemodynamics by measuring the middle cerebral artery (MCA) blood flow velocity by transcranial Doppler ultrasound (TCD), and the related factors just before delivery and within the 24 h after delivery.

METHODS

The study included 35 healthy pregnant women with a gestational age of >37 weeks who were in labor and a control group including healthy, age-matched, nonpregnant women (n = 24). Demographic characteristics and significant clinical information of pregnant women were recorded. The MCA blood flow velocity was assessed by TCD just before and within 24 h after delivery. The parameters assessed by TCD were mean cerebral blood flow velocity (MCBFV), peak systolic velocity (PSV), pulsatility index (PI), resistance index (RI), and systolic/diastolic ratio.

RESULTS

There was no significant difference between the pregnant and nonpregnant women regarding age (27 ± 5 years versus 28 ± 7 years; p = .751). The MCBFV, PSV, PI, and RI showed a significant increase within the 24 h after delivery as compared with those before delivery. Comparison of the pregnant women with the control group in terms of the values of all parameters related to the MCA blood flow velocity revealed that the values that were significantly low before delivery reached to the level of the control group after delivery Conclusion: The findings of this study demonstrated that the blood flow velocity of the MCA decreased during the late pregnancy period and increased in the early postpartum period to the level similar to that of the nonpregnant group.

Cerebral haemodynamics in early puerperium: A prospective study

AIM

Prospective study on 900 consecutive puerperae to assess normal values and range of the blood flow velocity in the middle cerebral artery in both hemispheres.

MATERIAL AND METHOD

M1 and M2 segments of both middle cerebral arteries were assessed in all subjects within 96 hours of delivery. Mean flow velocity was recorded after adjusting for insonation angle. Lindegaard index (LI = middle cerebral artery-Internal Carotid Artery mean flow velocity ratio) was calculated whenever the mean flow velocity exceeded 100 cm/second. Asymmetry indexes were calculated inter hemispherically for M1 and M2 segments separately.

RESULTS

Mean flow velocities were 74 ± 17 and 72 ± 17 in right and 73 ± 17 and 72 ± 17 cm/second in the left M1 and M2, respectively. A total of 136 subjects (12.1%) exceeded the threshold of 100 cm/second, but LI was consistently <3 in all of them. Mean flow velocity was inversely and independently correlated to haemoglobin levels and to parity. Mean asymmetry indexes were 0.25 ± 23 in M1 and 0.45 ± 25 in M2.

CONCLUSION

Mean flow velocity in the middle cerebral artery of healthy subjects in early puerperium is higher than in age-matched non-puerperal women and may exceed the threshold of 100 cm/second with no evidence of intracranial spasm, because of blood loss during delivery. Mean flow velocity is independently correlated with parity. Right-to-left mean flow velocity asymmetry may reach 50% as a consequence of a transient imbalance in vascular tone regulation.

Near-infrared spectrometry in pregnancy: progress and perspectives, a review of literature

Near-infrared spectroscopy (NIRS) allows continuous noninvasive monitoring of in vivo oxygenation in selected tissues. It has been used primarily as a research tool for several years, but it is seeing wider application in the clinical arena all over the world. It was recently used to monitor brain circulation in cardiac surgery, carotid endarteriectomy, neurosurgery and robotic surgery. According to the few studies used NIRS in pregnancy, it may be helpful to assess the impact of severe forms of preeclampsia on brain circulation, to evaluate the efficacy of different treatments. It may also be used during cesarean section to detect earlier sudden complications. The evaluation of placental function via abdominal maternal approach to detect fetal growth restriction is a new field of application of NIRS.

Late postpartum eclampsia complicated with posterior reversible encephalopathy syndrome: a case report and a literature review

Posterior reversible encephalopathy syndrome (PRES) is a rare but serious clinical-neuroradiological entity characterized by headache, vomiting, visual disturbances, altered mental status, seizures, and unconsciousness associated with the characteristic imaging findings including sub-cortical vasogenic edema at the bilateral parietal and occipital lobes. We describe a case of 28-year-old PRES patient secondary to delayed maternal postpartum eclampsia. This patient was not initially diagnosed with pre-eclampsia and PRES. The diagnosis was established after magnetic resonance imaging. After treatment this patient's PRES resolved. Early diagnosis and treatment are the keys to reverse PRES. A literature review for PRES is provided in this report.

Cerebral oximetry assessed by near-infrared spectrometry during preeclampsia: an observational study: impact of magnesium sulfate administration

OBJECTIVES

To determine the regional cerebral oxygen saturation of hemoglobin (rcSO2) in severe preeclamptic parturients exhibiting neurologic symptoms compared with healthy pregnant women (control) and to describe the effects of MgSO4 infusion on rcSO2 and cerebral and systemic hemodynamic variables.

DESIGN

Prospective, observational study.

SETTING

Obstetric critical care unit in a university-affiliated hospital.

PATIENTS

Twenty severe preeclamptic parturients presenting with neurologic signs before any administration of MgSO4, and 20 control parturients.

INTERVENTION

Infusion of MgSO4 in severe preeclamptic patients.

MEASUREMENTS AND MAIN RESULTS

We measured rcSO2 using near-infrared spectroscopy, blood flow velocities of the middle cerebral artery, and cardiac output at baseline, 5 minutes, 1 hour, and 6 hours after the MgSO4 bolus (4 g), followed by continuous MgSO4 infusion (1 g/h). These measurements were also obtained in 20 control parturients at baseline and 6 hours. Baseline rcSO2 was significantly lower in the severe preeclamptic group: 61% (56-69) vs 66% (63-71) (p = 0.037). At inclusion, blood pressures were significantly higher in the severe preeclamptic group compared with the control group, whereas cardiac output and transcranial Doppler readings were similar. Five minutes after the MgSO4 bolus infusion, a median increase of 8.6% (3.2-18.1) in rcSO2 was observed (p = 0.007), reaching values of the control group that were maintained up to 6 hours. Blood pressures and systolic velocities of the middle cerebral artery significantly decreased (p < 0.01) after the MgSO4 bolus, whereas cardiac output did not change. The percentage increase in rcSO2 was negatively correlated to the mean blood pressure (r = 0.60, p < 0.0001).

CONCLUSION

Cerebral oxygenation impairment can be detected by near-infrared spectroscopy monitoring in severe preeclamptic parturients. These results suggested the presence of disorders in cerebral microcirculation and/or changes in cerebral oxygenation. MgSO4 infusion in patients with severe preeclampsia restored rcSO2 to control levels with no systemic side effects. Further studies are needed to confirm the usefulness of near-infrared spectroscopy monitoring in patients with preeclampsia and to assess the action of other antihypertensive therapies on rcSO2.

Power M-mode transcranial Doppler examination of the ophthalmic artery in pregnancy: standard operating procedure and review of the literature

Our aim was to describe the standard operating procedure for transcranial Doppler investigation of the ophthalmic artery in pregnancy, determine the interobserver and intraobserver variability using power M-mode technology, and review the existing literature. Accordingly, 27 healthy pregnant or immediately postpartum women were enrolled and underwent transcranial Doppler investigation of the ophthalmic artery using power M-mode technology. Good interobserver and intraobserver variability was observed for both, especially with respect to the clinically important indices. Transcranial Doppler power M-mode examination of the ophthalmic artery is easy and reproducible and holds a great deal of potential for investigation in pregnancy.

Cerebro vascular reactivity (CVR) of middle cerebral artery in response to CO2 5% inhalation in preeclamptic women

OBJECTIVE

To compare the cerebro vascular reactivity (CVR) of middle cerebral artery (MCA) in response to CO2 5% inhalation between preeclamptic and normotensive pregnant women, also, between mild and severe preeclampsia.

STUDY DESIGN

A comparative study was performed on 61 women with preeclampsia and 65 normotensive pregnant women who were in the third trimester of gestation. MCA transcranial Doppler ultrasound was used to measure CVR in response to CO2 5% inhalation. Pulsatility index (PI), resistance index (RI), blood pressure, maternal age, gestational age and gravidity were also recorded.

RESULTS

Baseline PI and RI were lower in the preeclamptic group (p < 0.05). Inhalation of CO2 5% caused significant increase in CVR among normotensive pregnant women in comparison with preeclamptic group (1.006 ± 0.229 versus 0.503 ± 0.209, p = 0.0001). Significantly, more cerebral vasodilatation was found among mild preeclamptic women in comparison with severe preeclamptic women (0.583 ± 0.193 versus 0.383 ± 0.173, p = 0.0001). The receiver operating characteristics curve analysis revealed acceptable difference between CO2 stimulation test of preeclamptic and normotensive women (Area under curve = 0.973, p = 0.0001).

CONCLUSION

CVR in response to CO2 5% is less in preeclamptic pregnant women than normotensives, also, in severe preeclampsia, it is less than mild preeclampsia.

Doppler sonography of maternal cerebral arteries in pregnancy: side-to-side differences

BACKGROUND/AIMS

To study side-to-side differences in blood flow of the common and internal carotid arteries, and the vertebral arteries (VAs) in women with uncomplicated pregnancies as a first step to build a reference values chart.

METHODS

A total of 155 healthy pregnant women between 20 and 40 weeks' gestation were included. Doppler sonography of the common and internal carotid arteries and VAs was performed on both sides. Parameters measured included diameter, peak systolic velocity, systolic-diastolic ratio, end-diastolic velocity, pulsatility index and resistance index. Statistical analysis was performed using the S-Plus 8.0 program. Normality was determined using the Kolmogorov-Smirnov test. Differences between sides were tested using Student's paired t test, association using linear correlation, and agreement using the Bland-Altman method.

RESULTS

Mean values were equal between sides for all parameters with the exception of the end-diastolic velocity in the VAs. The association and agreement between the measurements taken from the right and left sides were poor. Bland-Altman plots also indicated low agreement between sides. All parameters showed significant right-to-left differences.

CONCLUSION

Despite the equality between means, right and left flows through the vessels studied differed as there was poor association and agreement.

Maternal cerebral blood flow during normal pregnancy: a cross-sectional study

OBJECTIVE

Pregnancy is associated with substantial changes in the maternal circulatory physiology. Our aim was to investigate maternal cerebral blood flow (CBF) during normal pregnancies.

STUDY DESIGN

We prospectively measured maternal CBF in 210 low-risk pregnant women at different gestational ages, and in 15 nonpregnant women. CBF was assessed by measuring blood flow volume in the internal carotid artery (ICA) by dual-beam angle-independent digital Doppler ultrasound.

RESULTS

ICA blood flow volume increased during pregnancy from 318 mL/min ± 40.6 mL/min in the first trimester to 382.1 mL/min ± 50.0 mL/min during the third trimester, corresponding to CBF values of 44.4 and 51.8 mL/min(-1)/100 g(-1), respectively (P < .0001). CBF changes were associated with progressive decrease in cerebral vascular resistance and moderate increase in ICA diameter.

CONCLUSION

Maternal CBF is gradually increasing during normal pregnancy. Vasorelaxing impact of estrogens and other factors on cerebral vessels may explain the changes in CBF during pregnancy.

Eclampsia: a neurological perspective

Eclampsia is a poorly understood disorder characterized by seizures or unexplained coma in setting of gestational hypertension. Its neurological manifestations are varied and are an important cause of the morbidity and mortality associated. We present a comprehensive prospective study of forty women recruited over four years describing neurological symptoms and signs, neuroimaging and laboratory studies as well as prognosis including 3-6 months follow-up. The seizures occurred in the postpartum period in majority of women (55%), while 45% had seizures before labor, and the rest (5%) during labor. Interestingly, one third of the women suffered their first seizures more than 48 h postpartum (late postpartum eclampsia). A sizable minority suffered more than one seizure and some had documented partial seizures. Headache preceded seizures by more than a day and was described as throbbing or pounding pain by most. The visual symptoms in decreasing frequency were blurring, blindness, scotoma and visual processing deficits. The most common finding during the neurological exam was memory deficits, followed by increased deep tendon reflexes (asymmetric in some), visual perception deficits, visual information processing deficits, altered mental status and cranial nerve deficits. Intracranial or intraspinal pressure when examined was elevated. Among neuroimaging studies, MRI was more sensitive compared to CT scan. The MRI abnormalities included both white as well as gray matter and the most common location of abnormalities was high frontal/parietal lobe. The laboratory studies revealed proteinuria in majority, but not in all. The liver function tests were abnormal in many, while few patients had HELLP syndrome. The neurological deficits resolved by the time of discharge in all. At follow-up, some patients developed new neurological problems such as recurrent headaches or seizures.

Neuropsychological performance in normal pregnancy and preeclampsia

OBJECTIVE

The objective of the study was to evaluate neurocognitive function in preeclampsia and normal pregnancy.

STUDY DESIGN

Three groups (each n = 15) were studied before and after delivery using standard neurocognitive test techniques. Group A consisted of normal laboring patients; group B, preeclamptics receiving magnesium; and group C, women in preterm labor receiving MgSO4 tocolysis (Mg control). The tests, examining attention, working memory, explicit memory, auditory comprehension, and measures for emotional distress, pain, and fatigue were analyzed via 4-way multivariate analysis of variance and multiple t tests.

RESULTS

Preeclamptics receiving MgSO4 had better attention and working memory (P = .05), compared with normal laboring women and the preterm patients. Explicit memory was impaired in all groups, and this could not be accounted for by pain or emotional distress.

CONCLUSION

We could detect no cognitive defects in preeclamptics, compared with normotensive gravidas, at least while the cerebral vasodilator MgSO4 is being infused.

Increased cerebral blood flow in preeclampsia with magnetic resonance imaging

OBJECTIVE

The purpose of this study was to compare third trimester and nonpregnant cerebral blood flow of women with preeclampsia to normotensive control subjects with the use of magnetic resonance imaging techniques.

STUDY DESIGN

Nine normotensive pregnant women and 12 untreated women with preeclampsia underwent velocity-encoded phase contrast magnetic resonance imaging of the bilateral middle and posterior cerebral arteries in the third trimester and at 6 to 8 weeks after delivery. The Student t test was used for comparison, with a probability value of <.05 considered significant.

RESULTS

Third-trimester large cerebral artery blood flow was significantly higher in preeclampsia. Mean vessel diameter was unchanged, except for the left posterior cerebral artery. There was no difference in mean vessel diameter or cerebral blood flow between the 2 groups while the women were not pregnant.

CONCLUSION

Cerebral blood flow is increased significantly in preeclampsia. We hypothesize that increased cerebral blood flow ultimately could lead to eclampsia through hyperperfusion and the development of vasogenic edema.

A case of reversible postpartum cytotoxic edema in preeclampsia

We report on a 32-year-old woman who developed reversible cortical blindness and right-sided weakness after cesarean section at 36 weeks of gestation, due to preeclampsia. An initial brain MRI demonstrated high signal intensity lesions in the bilateral occipito-parietal and left frontal lobes on T2-weighted and diffusion-weighted imaging. All of the lesions showed low signal intensity on apparent diffusion coefficient (ADC) map, which were compatible with cytotoxic edema, and MR angiography (MRA) showed diffuse vasospasm of the intracranial vessels. A follow-up brain MRI showed that most of the lesions disappeared and the vasospasm also resolved. This case suggests that the cytotoxic edema in preeclampsia may evolve differently from the pattern in cerebral infarction and explains the relatively benign course of the neurological signs in preeclampsia.