No long-term impairment of cerebral autoregulation after preeclampsia

A systematic review, meta-analysis, and meta-regression amalgamating the driven approaches used to quantify dynamic cerebral autoregulation

Numerous driven techniques have been utilized to assess dynamic cerebral autoregulation (dCA) in healthy and clinical populations. The current review aimed to amalgamate this literature and provide recommendations to create greater standardization for future research. The PubMed database was searched with inclusion criteria consisting of original research articles using driven dCA assessments in humans. Risk of bias were completed using Scottish Intercollegiate Guidelines Network and Methodological Index for Non-Randomized Studies. Meta-analyses were conducted for coherence, phase, and gain metrics at 0.05 and 0.10 Hz using deep-breathing, oscillatory lower body negative pressure (OLBNP), sit-to-stand maneuvers, and squat-stand maneuvers. A total of 113 studies were included, with 40 of these incorporating clinical populations. A total of 4126 participants were identified, with younger adults (18-40 years) being the most studied population. The most common techniques were squat-stands (n = 43), deep-breathing (n = 25), OLBNP (n = 20), and sit-to-stands (n = 16). Pooled coherence point estimates were: OLBNP 0.70 (95%CI:0.59-0.82), sit-to-stands 0.87 (95%CI:0.79-0.95), and squat-stands 0.98 (95%CI:0.98-0.99) at 0.05 Hz; and deep-breathing 0.90 (95%CI:0.81-0.99); OLBNP 0.67 (95%CI:0.44-0.90); and squat-stands 0.99 (95%CI:0.99-0.99) at 0.10 Hz. This review summarizes clinical findings, discusses the pros/cons of the 11 unique driven techniques included, and provides recommendations for future investigations into the unique physiological intricacies of dCA.

Blood-Brain Barrier Dysfunction in Hypertensive Disorders of Pregnancy

PURPOSE OF REVIEW

The incidence of hypertensive disorders of pregnancy (HDP), especially preeclampsia has increased significantly over the last two decades. Patients with these disorders often report cerebral and visual symptoms, which are listed as potential diagnosis criteria for preeclampsia, if accompanied by new-onset hypertension. Recent studies indicate that cerebral complications in HDP patients are associated with a compromised blood-brain barrier (BBB). The purpose of this review is to highlight the recent literature focused on the BBB in HDP, identify gaps in knowledge, and discuss future directions in this research area.

RECENT FINDINGS

Majority of the studies addressing BBB changes in HDP are focused on preeclampsia. Recent studies show that hypertension induces increased association of perivascular macrophages/microglia to the cerebral vessels, increased circulating extracellular vesicles, and decreased autoregulation of cerebral blood flow. There is a critical need for more animal studies targeted to protecting the BBB and preventing cerebrovascular complications in the context of HDP. More clinical studies are needed that investigate both the short- and long-term interplay between each HDP subtype and BBB and cognitive function.

Risk of Stroke After Posterior Reversible Encephalopathy Syndrome

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) can cause short-term cerebrovascular complications, such as brain infarction and hemorrhage. We hypothesized that PRES is also associated with an increased long-term risk of stroke.

METHODS

We performed a retrospective cohort study in the United States using statewide all-payer claims data from 2016 to 2018 on all admissions to nonfederal hospitals in 11 states. Adults with PRES were compared with adults with renal colic (negative control) and transient ischemic attack (TIA; positive control). Any stroke and the secondary outcomes of ischemic and hemorrhagic stroke were ascertained using International Classification of Diseases, Tenth Revision, Clinical Modification codes. We excluded prevalent stroke. We used time-to-event statistics to calculate incidence rates and Cox proportional hazards analyses to evaluate the association between PRES and stroke, adjusting for demographics and stroke risk factors. In a sensitivity analysis, outcomes within 2 weeks of index admission were excluded.

RESULTS

We identified 1606 patients with PRES, 1192 with renal colic, and 38 216 with TIA. Patients with PRES had a mean age of 56±17 years; 72% were women. Over a median follow-up of 0.9 years, the stroke incidence per 100 person-years was 6.1 (95% CI, 5.0-7.4) after PRES, 1.0 (95% CI, 0.62-1.8) after renal colic, and 9.7 (95% CI, 9.4-10.0) after TIA. After statistical adjustment for patient characteristics and risk factors, patients with PRES had an elevated risk of stroke compared with renal colic (hazard ratio [HR], 2.3 [95% CI, 1.7-3.0]), but lower risk than patients with TIA (HR, 0.67 [95% CI, 0.54-0.82]). In secondary analyses, compared with TIA, PRES was associated with hemorrhagic stroke (HR, 2.0 [95% CI, 1.4-2.9]). PRES was associated with ischemic stroke when compared with renal colic (HR, 1.9 [95% CI, 1.4-2.7]) but not when compared with TIA (HR, 0.49 [95% CI, 0.38-0.63]). Results were similar with 2-week washout.

CONCLUSIONS

Patients with PRES had an elevated risk of incident stroke.

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.

Neurology of Preeclampsia and Related Disorders: an Update in Neuro-obstetrics

PURPOSE OF REVIEW

Preeclampsia and related hypertensive disorders of pregnancy affect up to 10% of pregnancies. Neurological complications are common and neurologists often become involved in the care of obstetric patients with preeclampsia. Here, we review the definition(s), epidemiology, clinical features, and pathophysiology of preeclampsia, focusing on maternal neurological complications and headache as a common presenting symptom of preeclampsia.

RECENT FINDINGS

Neurological symptoms are early and disease-defining features of preeclampsia. Neurological complications of preeclampsia may include headaches, visual symptoms, cerebral edema, seizures, or acute cerebrovascular disorders such as intracerebral hemorrhage or reversible cerebral vasoconstriction syndrome. A history of migraine is an independent risk factor for vascular diseases during pregnancy, including preeclampsia and maternal stroke. The pathophysiology of both preeclampsia and migraine is complex, and the mechanisms linking the two are not fully understood. Overlapping clinical and pathophysiological features of migraine and preeclampsia include inflammation, vascular endothelial dysfunction, and changes in vasoreactivity. Neurological complications are recognized as a major contributor to maternal morbidity and mortality. Pregnant and postpartum women commonly present with headache, and red flags in the clinical history and examination should prompt urgent neuroimaging and laboratory evaluation. A focused headache history should be elicited from patients as part of routine obstetrical care to identify patients at an increased risk of preeclampsia and related hypertensive disorders of pregnancy. Collaborative models of care and scientific investigation in the emerging field of neuro-obstetrics have the common goal of reducing the risk of maternal neurological morbidity and mortality from preeclampsia.

Cerebral Autoregulation and Neurovascular Coupling after Craniospinal Irradiation in Long-Term Survivors of Malignant Pediatric Brain Tumors of the Posterior Fossa

INTRODUCTION

Long-term survivors of craniospinal irradiation have an increased risk for stroke which increases with radiation dose and follow-up time. Radiotherapy induces structural changes of the cerebral vasculature, affecting both, large, and small vessels. It is unknown how these structural changes affect functional mechanisms of cerebral blood flow regulation such as cerebral autoregulation and neurovascular coupling.

METHODS

Using the transcranial Doppler, we compared dynamic cerebral autoregulation and neurovascular coupling of 12 patients after long-term survival of craniospinal irradiation due to a malignant pediatric brain tumor of the posterior fossa and 12 age- and sex-matched healthy patients. Mean arterial blood pressure and cerebral blood flow velocities in the middle and posterior cerebral artery were recorded at rest during normal breathing to assess cerebral autoregulation (transfer function parameters phase and gain, as well as the correlation coefficient indices Mx, Sx, and Dx), and during 10 cycles of a visual task to assess neurovascular coupling (parameters time delay, natural frequency, gain, attenuation, and rate time).

RESULTS

Parameters of cerebral autoregulation showed a consistent trend toward reduced cerebral autoregulation in patients that did not reach statistical significance. Neurovascular coupling was not altered after craniospinal irradiation.

CONCLUSION

In this pilot study, we demonstrated a trend toward reduced cerebral autoregulation, and no alteration of neurovascular coupling after irradiation in long-term survivors of malignant pediatric brain tumors of the posterior fossa.

Augmented cerebral blood velocity in response to isometric handgrip exercise in women with a history of preeclampsia

Preeclampsia (PE) is a hypertensive disorder of pregnancy described as a condition of excessive sympathoexcitation. PE places a woman at increased risk for lifelong hypertension and cognitive impairment. Cerebral blood velocity is blunted in response to a vasoactive stimulus in women with a history of PE. This study investigated how a sympathoexcitatory stimulus affects cerebral blood velocity in women with a history of PE. Middle cerebral artery blood velocity (MCAv) and beat-to-beat mean arterial blood pressure (MAP) were measured in postmenopausal women with a history of PE (n = 21; age = 59 ± 5 yr) and a history of a normotensive pregnancy (NP; n = 27; age = 58 ± 4 yr), at baseline, during isometric handgrip to fatigue (IHG) followed by postexercise ischemia (PEI), and a recovery period (REC). Baseline MAP and MAP responses to IHG and PEI did not differ between groups. MCAv at baseline and throughout the stimulus was lower in PE women compared with NP women (P < 0.05 for all). MCAv increased during IHG in both groups (P < 0.05). This increase in MCAv was greater in PE compared with NP women during IHG and REC (IHG: PE 13 ± 2% vs. NP 9 ± 2%; REC: PE 3 ± 2% vs. NP -2 ± 2%; P < 0.05 for both). Thus, a history of PE is associated with low baseline cerebral blood velocity but an augmented response to a sympathoexcitatory stimulus. These changes in cerebral blood flow regulation may lead to an increased risk for cognitive impairment in women with a history of PE.