Posterior Reversible Encephalopathy Syndrome in severe preeclampsia: case report and literature review

Preeclampsia history and postpartum risk of cerebrovascular disease and cognitive impairment: Potential mechanisms

Hypertensive disorders of pregnancy such as preeclampsia, eclampsia, superimposed preeclampsia, and gestational hypertension are major causes of fetal and maternal morbidity and mortality. Women with a history of hypertensive pregnancy disorders have increased risk of stroke and cognitive impairments later in life. Moreover, women with a history of preeclampsia have increased risk of mortality from diseases including stroke, Alzheimer's disease, and cardiovascular disease. The underlying pathophysiological mechanisms are currently not fully known. Here, we present clinical, epidemiological, and preclinical studies focused on evaluating the long-term cerebrovascular and cognitive dysfunction that affect women with a history of hypertensive pregnancy disorders and discuss potential underlying pathophysiological mechanisms.

Preeclampsia pathophysiology and adverse outcomes during pregnancy and postpartum

Background

Preeclampsia is a disease with far-reaching consequences that extend beyond the immediate postpartum period and have a significant impact later in life. Preeclampsia exerts an effect on most organ systems in the body. These sequelae are mediated in part by the incompletely elucidated pathophysiology of preeclampsia and the associated vascular changes.

Content

Current research focuses on unraveling the pathophysiology of preeclampsia with the goal of implementing accurate screening and treatment modalities based on disease development and progression. Preeclampsia causes significant short- and long-term maternal morbidity and mortality, not only in the cardiovascular system but also in other organ systems throughout the body. This impact persists beyond pregnancy and the immediate postpartum period.

Summary

The goal of this review is to discuss the current understanding of the pathophysiology of preeclampsia as it relates to the adverse health consequences in patients impacted by this disease, along with a brief discussion of ways to improve overall outcomes.

The Serotonin-Immune Axis in Preeclampsia

PURPOSE OF REVIEW

To review the literature and detail the potential immune mechanisms by which hyperserotonemia may drive pro-inflammation in preeclampsia and to provide insights into potential avenues for therapeutic discovery.

RECENT FINDINGS

Preeclampsia is a severe hypertensive complication of pregnancy associated with significant maternal and fetal risk. Though it lacks any effective treatment aside from delivery of the fetus and placenta, recent work suggests that targeting serotonin systems may be one effective therapeutic avenue. Serotonin dysregulation underlies multiple domains of physiologic dysfunction in preeclampsia, including vascular hyporeactivity and excess platelet aggregation. Broadly, serotonin is increased across maternal and placental domains, driven by decreased catabolism and increased availability of tryptophan precursor. Pro-inflammation, another hallmark of the disease, may drive hyperserotonemia in preeclampsia. Interactions between immunologic dysfunction and hyperserotonemia in preeclampsia depend on multiple mechanisms, which we discuss in the present review. These include altered immune cell, kynurenine pathway metabolism, and aberrant cytokine production mechanisms, which we detail. Future work may leverage animal and in vitro models to reveal serotonin targets in the context of preeclampsia's immune biology, and ultimately to mitigate vascular and platelet dysfunction in the disease. Hyperserotonemia in preeclampsia drives pro-inflammation via metabolic, immune cell, and cytokine-based mechanisms. These immune mechanisms may be targeted to treat vascular and platelet endophenotypes in preeclampsia.

Cerebral Blood Flow Regulation in Pregnancy, Hypertension, and Hypertensive Disorders of Pregnancy

The regulation of cerebral blood flow (CBF) allows for the metabolic demands of the brain to be met and for normal brain function including cognition (learning and memory). Regulation of CBF ensures relatively constant blood flow to the brain despite changes in systemic blood pressure, protecting the fragile micro-vessels from damage. CBF regulation is altered in pregnancy and is further altered by hypertension and hypertensive disorders of pregnancy including preeclampsia. The mechanisms contributing to changes in CBF in normal pregnancy, hypertension, and preeclampsia have not been fully elucidated. This review summarizes what is known about changes in CBF regulation during pregnancy, hypertension, and preeclampsia.

Postpartum Posterior Reversible Encephalopathy Syndrome (PRES): Three Case Reports and Literature Review

Posterior reversible encephalopathy syndrome is a rare complication generally associated with headache and acute changes in blood pressure. Delay in the diagnosis and treatment may result in death or in irreversible neurological sequelae. We present three cases of PRES occurring in young women during puerperium. We report a literature review ranged from January 1990 to June 2015 describing clinical features, diagnostic and medical approach, and maternal outcome.

Post-partum posterior reversible encephalopathy syndrome requiring decompressive craniectomy: case report and review of the literature

Posterior reversible encephalopathy syndrome (PRES) is an uncommon but potentially devastating syndrome if not recognized and treated appropriately. As the name implies, recognition of the condition and proper management may reverse the clinical and radiological findings. However, diagnosis is not always straightforward. We present the case of a 24-year-old female who was 4 days post-partum and presented with headache, neck pain, and new-onset seizures. She had undergone epidural anesthesia during labor, and initial imaging was suggestive of intracranial hypotension versus pachymeningitis. Despite initial conservative therapy including anti-epileptic drugs, magnesium therapy, empiric antibiotics, and Trendelenburg positioning, the patient continued to deteriorate. Follow-up imaging was suggestive of PRES with signs of intracranial hypertension. The patient underwent a decompressive suboccipital craniectomy for refractory and severe PRES and later fully recovered. This case highlights the sometimes difficult diagnosis of PRES, possible association with pregnancy, eclampsia/preeclampsia and/or cerebrospinal fluid drainage, and the rare but life-saving need for decompression in severe cases.

Magnesium Sulfate Prevents Placental Ischemia-Induced Increases in Brain Water Content and Cerebrospinal Fluid Cytokines in Pregnant Rats

Magnesium sulfate (MgSO₄) is the most widely used therapy in the clinic to prevent the progression of preeclampsia, a hypertensive disorder of pregnancy, to eclampsia. Eclampsia, manifested as unexplained seizures and/or coma during pregnancy or postpartum, accounts for ~13% of maternal deaths worldwide. While MgSO₄ continues to be used in the clinic, the mechanisms by which it exerts its protective actions are not well understood. In this study, we tested the hypothesis that MgSO₄ protects against placental ischemia-induced increases in brain water content and cerebrospinal fluid cytokines. To test this hypothesis, MgSO₄ was administered via mini-osmotic pump (60 mg/day, i.p.) to pregnant and placental ischemic rats, induced by mechanical reduction of uterine perfusion pressure, from gestational day 14–19. This treatment regimen of MgSO₄ led to therapeutic level of 2.8 ± 0.6 mmol/L Mg in plasma. MgSO₄ had no effect on improving placental ischemia-induced changes in mean arterial pressure, number of live fetuses, or fetal and placental weight. Placental ischemia increased, while MgSO₄ prevented the increase in water content in the anterior cerebrum. Cytokine and chemokine levels were measured in the cerebrospinal fluid using a multi-plex assay. Results demonstrate that cerebrospinal fluid, obtained via the cisterna magna, had reduced protein, albumin, interleukin (IL)-17A, IL-18, IL-2, eotaxin, fractalkine, interferon gamma, vascular endothelial growth factor (VEGF), and macrophage inflammatory protein (MIP)-2 following MgSO₄ treatment. These data support the hypothesis that MgSO₄ offers neuroprotection by preventing placental ischemia-induced cerebral edema and reducing levels of cytokines/chemokines in the cerebrospinal fluid.

A global amnesia associated with the specific variant of posterior reversible encephalopathy syndrome (PRES) that developed due to severe preeclampsia and malignant hypertension

A case is reported of a 26-year-old primiparous woman in the 32nd week of gestation who presented to the emergency department with the symptoms of a severe headache, nausea and vomiting. The patient was diagnosed with preeclampsia that later progressed to eclampsia. This state was characterized by a sudden onset of a headache and diplopia that advanced to cortical blindness and precipitated significant alterations in mental status, most notable being global amnesia that resolved within 48 h. A post-partum magnetic resonance imaging of the brain in FLAIR mode revealed multiple cortico-subcortical areas of hyperintense signals suggestive of edematous lesions that chiefly involved occipital and parietal lobes with additional atypical manifestations. Such radiologic findings suggested a posterior reversible encephalopathy syndrome variant with the global amnesia as an extraordinary constituent. This unique feature should be acknowledged when treating a preeclamptic or hypertensive patient that exhibits neurological symptomatology and vision disturbances.

Transient Global Amnesia with Reversible White Matter Lesions: A Variant of Posterior Reversible Encephalopathy Syndrome?

Transient global amnesia (TGA) is a self-limited disease characterized by isolated amnesia, which resolves within 24 h. In contrast, posterior reversible encephalopathy syndrome (PRES) is a potentially life-threatening disease that usually presents with seizures, altered mental status, headache, and visual disturbances. It is characterized by reversible vasogenic edema that predominantly involves the parieto-occipital subcortical white matter as shown by neuroimaging studies. To date, there have been no reported cases of PRES with a clinical course resembling TGA. Here we report the case of a 58-year-old woman who presented with isolated amnesia and headache. On admission, her blood pressure was 187/100 mmHg. She had complete anterograde amnesia and slight retrograde amnesia without other neurological findings. After the treatment of her hypertension, the amnesia resolved within 24 h. Although the initial magnetic resonance image (MRI) was almost normal, the fluid attenuation inversion recovery (FLAIR) images of the MRI on the next day revealed several small foci of high intensity areas in the fronto-parieto-occipital subcortical white matter, presumed to be vasogenic edema in PRES. The lesions disappeared one month later. This case suggests that PRES can mimic the clinical course of TGA. PRES should be considered in the differential diagnosis for TGA.

Placental ischemia-induced increases in brain water content and cerebrovascular permeability: role of TNF-α

Cerebrovascular complications and increased risk of encephalopathies are characteristic of preeclampsia and contribute to 40% of preeclampsia/eclampsia-related deaths. Circulating tumor necrosis factor-α (TNF-α) is elevated in preeclamptic women, and infusion of TNF-α into pregnant rats mimics characteristics of preeclampsia. While this suggests that TNF-α has a mechanistic role to promote preeclampsia, the impact of TNF-α on the cerebral vasculature during pregnancy remains unclear. We tested the hypothesis that TNF-α contributes to cerebrovascular abnormalities during placental ischemia by first infusing TNF-α in pregnant rats (200 ng/day ip, from gestational day 14 to 19) at levels to mimic those reported in preeclamptic women. TNF-α increased mean arterial pressure (MAP, P < 0.05) and brain water content in the anterior cerebrum (P < 0.05); however, TNF-α infusion had no effect on blood-brain barrier (BBB) permeability in the anterior cerebrum or posterior cerebrum. We then assessed the role of endogenous TNF-α in mediating these abnormalities in a model of placental ischemia induced by reducing uterine perfusion pressure followed by treatment with the soluble TNF-α receptor (etanercept, 0.8 mg/kg sc) on gestational day 18. Etanercept reduced placental ischemia-mediated increases in MAP, anterior brain water content (P < 0.05), and BBB permeability (202 ± 44% in placental ischemic rats to 101 ± 28% of normal pregnant rats). Our results indicate that TNF-α mechanistically contributes to cerebral edema by increasing BBB permeability and is an underlying factor in the development of cerebrovascular abnormalities associated with preeclampsia complicated by placental ischemia.

Therapy and differential diagnosis of posterior reversible encephalopathy syndrome (PRES) during pregnancy and postpartum

PURPOSE

Posterior reversible encephalopathy syndrome (PRES) is an usually reversible neuro-radiological clinical entity characterized by headache, confusion, visual disturbances or blindness and seizures. It rarely occurs without seizures.

METHODS

We conducted a literature review in MEDLINE about PRES during post partum and pregnancy, focusing on differential diagnosis and therapy. We reviewed 28 articles (case reports, original articles and reviews) describing PRES as well as a case of a severe, immediate postpartum HELLP syndrome (haemolysis, elevated liver enzyme levels, low platelet count) with PRES without generalized seizure.

RESULTS

The development of PRES after delivery is unusual. Magnetic resonance imaging represents the gold standard for the diagnosis of this condition. White matter oedema in the posterior cerebral hemispheres is typical on neuroimaging. PRES is reversible when early diagnosis is established and appropriate treatment is started without delay. The pathogenesis of PRES is discussed and the importance of a prompt diagnosis is emphasized, as the crucial role of rapid blood press reduction.

CONCLUSION

MRI is the diagnostic gold standard and it may be useful in the differential diagnosis. The goal of the therapy is to control elevated blood pressure and to prevent seizures or promptly manage it.

Placental ischemia in pregnant rats impairs cerebral blood flow autoregulation and increases blood-brain barrier permeability

Cerebrovascular events contribute to ~40% of preeclampsia/eclampsia‐related deaths, and neurological symptoms are common among preeclamptic patients. We previously reported that placental ischemia, induced by reducing utero‐placental perfusion pressure, leads to impaired myogenic reactivity and cerebral edema in the pregnant rat. Whether the impaired myogenic reactivity is associated with altered cerebral blood flow (CBF) autoregulation and the edema is due to altered blood–brain barrier (BBB) permeability remains unclear. Therefore, we tested the hypothesis that placental ischemia leads to impaired CBF autoregulation and a disruption of the BBB. CBF autoregulation, measured in vivo by laser Doppler flowmetry, was significantly impaired in placental ischemic rats. Brain water content was increased in the anterior cerebrum of placental ischemic rats and BBB permeability, assayed using the Evans blue extravasation method, was increased in the anterior cerebrum. The expression of the tight junction proteins: claudin‐1 was increased in the posterior cerebrum, while zonula occludens‐1, and occludin, were not significantly altered in either the anterior or posterior cerebrum. These results are consistent with the hypothesis that placental ischemia mediates anterior cerebral edema through impaired CBF autoregulation and associated increased transmission of pressure to small vessels that increases BBB permeability leading to cerebral edema.

Preeclampsia is associated with an increased risk for developing encephalopathies. A prevailing theory is that impaired cerebral blood flow autoregulation contributes to this process. Whether placental ischemia, commonly thought to be a major underlying factor in the development of preeclampsia, can cause impaired cerebral blood flow autoregulation is not clear. In this study, placental ischemia is experimentally induced to test this directly. The results show that placental ischemia in the pregnant rat causes marked impairment of cerebral blood flow autoregulation.