Cerebrovascular blood pressure autoregulation monitoring and postoperative transient ischemic attack in pediatric moyamoya vasculopathy

Cerebral autoregulation in paediatric and neonatal intensive care: A scoping review

Deranged cerebral autoregulation (CA) is associated with worse outcome in adult brain injury. Strategies for monitoring CA and maintaining the brain at its 'best CA status' have been implemented, however, this approach has not yet developed for the paediatric population. This scoping review aims to find up-to-date evidence on CA assessment in children and neonates with a view to identify patient categories in which CA has been measured so far, CA monitoring methods and its relationship with clinical outcome if any. A literature search was conducted for studies published within 31st December 2022 in 3 bibliographic databases. Out of 494 papers screened, this review includes 135 studies. Our literature search reveals evidence for CA measurement in the paediatric population across different diagnostic categories and age groups. The techniques adopted, indices and thresholds used to assess and define CA are heterogeneous. We discuss the relevance of available evidence for CA assessment in the paediatric population. However, due to small number of studies and heterogeneity of methods used, there is no conclusive evidence to support universal adoption of CA monitoring, technique, and methodology. This calls for further work to understand the clinical impact of CA monitoring in paediatric and neonatal intensive care.

Acute management of childhood stroke

PURPOSE OF REVIEW

The purpose of this paper is to review recent updates in the acute management of childhood arterial ischemic stroke, including reperfusion therapies and neuroprotective measures.

RECENT FINDINGS

With the emergence of pediatric stroke centers in recent years, processes facilitating rapid diagnosis and treatment have resulted in improved implementation of early targeted neuroprotective measures as well as the increased use of reperfusion therapies in childhood arterial ischemic stroke. Retrospective data has demonstrated that alteplase is safe in carefully selected children with arterial ischemic stroke in the first 4.5 h from symptom onset, though data regarding its efficacy in children are still lacking. There is also increasing data that suggests that thrombectomy in children with large vessel occlusion improves functional outcomes. Recent adult studies, including the use of Tenecteplase as an alteplase alternative and expansion of late thrombectomy to include patients with large ischemic cores, also are reviewed along with limitations to application of the adult data to pediatric care.

SUMMARY

There have been significant advances in the hyperacute care of children with ischemic stroke and early diagnosis and targeted management are of the upmost importance in improving long-term outcomes.

Flow volume mismatch dramatically affects transient neurologic symptoms after direct bypass in Moyamoya disease

Transient neurological events (TNEs) occur after bypass surgery in Moyamoya disease (MMD); however, their pathology remains unknown. To elucidate the pathophysiology of TNEs, we investigated their relationship with perioperative superficial temporal artery (STA) blood flow volume, which was evaluated using ultrasonography. Forty-nine patients with MMD, who underwent direct bypass surgery, were included and stratified into TNE and non-TNE groups, respectively. The STA blood flow volume was evaluated at four time points (preoperatively and 2-4, 7, and 10-14 days postoperatively), and a change in volume during the postoperative period was defined as a flow volume mismatch. We investigated the association between ultrasonographic findings of flow volume mismatch and TNEs and magnetic resonance imaging findings, such as the cortical hyperintensity belt (CHB) sign, using univariate and path analyses. The STA blood flow volume increased immediately postoperatively, gradually decreasing over time, in both groups. The TNE group showed a significant increase in blood flow volume 2-4 days postoperatively (P = 0.042). Flow volume mismatch was significantly larger in the TNE group than in the non-TNE group (P = 0.020). In the path analysis, STA flow volume mismatch showed a positive association with the CHB sign (P = 0.023) and TNEs (P = 0.000). Additionally, the CHB sign partially mediated the association between STA flow volume mismatch and TNEs. These results suggest that significantly high STA blood flow volume changes occurring during the acute postoperative period after direct bypass surgery in MMD are correlated with TNEs and the CHB sign, suggesting involvement in the pathophysiology of TNEs.

Perioperative Management of Pediatric Patients with Moyamoya Arteriopathy

Pediatric patients with moyamoya arteriopathy are at high risk for developing new onset transient or permanent neurologic deficits secondary to cerebral hypoperfusion, particularly in the perioperative period. It is therefore essential to carefully manage these patients in a multidisciplinary, coordinated effort to reduce the risk of new permanent neurologic deficits. However, little has been published on perioperative management of pediatric patients with moyamoya, particularly in the early postoperative period during intensive care unit admission. Our pediatric neurocritical care team sought to create a multidisciplinary periprocedural evidence- and consensus-based care pathway for high-risk pediatric patients with moyamoya arteriopathy undergoing anesthesia for any reason to decrease the incidence of periprocedural stroke or transient ischemic attack (TIA). We reviewed the literature to identify risk factors associated with perioperative stroke or TIA among patients with moyamoya and to gather data supporting specific perioperative management strategies. A multidisciplinary team from pediatric anesthesia, neurocritical care, nursing, child life, neurosurgery, interventional neuroradiology, neurology, and hematology created a care pathway for children with moyamoya undergoing anesthesia, classifying them as either high or standard risk, and applying an individualized perioperative management plan to high-risk patients. The incidence of neurologic sequelae before and after pathway implementation will be compared in future studies.

Transient ischemic attack after indirect revascularization surgery for pediatric patients with moyamoya disease: A retrospective study of intraoperative blood pressure

BACKGROUND

This study aimed to investigate the association between intraoperative blood pressure and postoperative transient ischemic attacks (TIAs) in pediatric patients with moyamoya disease after indirect revascularization surgery.

METHODS

We retrospectively reviewed the medical records of patients with moyamoya disease younger than 15 years who underwent indirect revascularizations under general anesthesia from 2013 to 2019. Perioperative clinical factors and intraoperative blood pressure data were collected and analyzed. Univariate and multivariable mixed-effect logistic regressions were used to identify predictors of postoperative TIA and symptom progression.

RESULTS

Among 444 hemispheres in 296 pediatric patients, 70 cases (16%) experienced postoperative TIAs within 2 weeks after surgery, and 34 cases (7.7%) developed postoperative symptom progression. Baseline mean blood pressure (MBP) (adjusted odds ratio, 1.261; 95% confidence interval, 1.037-1.528; P < 0.001), Average mean arterial pressure (MAP) (adjusted odds ratio, 1.137; 95% confidence interval, 1.052-1.228; P = 0.006), and Ipsilateral magnetic resonance angiography (MRA) score (adjusted odds ratio, 1.464; 95% confidence interval, 0.886-2.419; P = 0.012) were statistically significant risk factors for postoperative TIA. Average real variability of MAP (ARV-MAP), which were measures of intraoperative MAP variability (adjusted odds ratio, 4.731; 95% confidence interval, 1.419-15.257; P = 0.003) and maximum MAP declination (MaxD-MAP) (adjusted odds ratio, 1.271; 95% confidence interval, 1.013-1.520; P = 0.010) were statistically significant risk factors for postoperative symptom progression.

CONCLUSION

Higher pre-induction baseline blood pressure and ipsilateral MRA score were independent risk factors predicting postoperative TIA in pediatric patients with moyamoya disease after indirect revascularization. The high variability and drastic decline in intraoperative MAP showed predictive value in postoperative symptom progression.

Arterial spin labeling for moyamoya angiopathy: A preoperative and postoperative evaluation method

Objectives

Studies have shown that arterial spin labeling (ASL) effectively replaces traditional MRI perfusion imaging for detecting cerebral blood flow (CBF) in patients with Moyamoya angiopathy (MMA). However, there are few reports on the relationship between neovascularization and cerebral perfusion in patients with MMA. The aim of this study is to investigate the effects of neovascularization on cerebral perfusion with MMA after bypass surgery.

Methods

We selected patients with MMA in the Department of Neurosurgery between September 2019 and August 2021 and enrolled them based on the inclusion and exclusion criteria. ASL imaging was used to monitor the baseline CBF level before surgery and determine the changes in cerebral vessels at postoperative 1 week and 6 months, respectively. The Alberta stroke grade, modified Rankin Scale (mRS), and digital subtraction angiography images were used to evaluate the effect of postoperative CBF status and prognosis. Ninety hemispheres from 51 patients were included in this study. There were no significant differences in the baseline data of the enrolled patients. At 1 week and 6 months post-surgery, the CBF state in the operation area was significantly changed compared with that at baseline (P < 0.05). The preoperative Alberta score (t = 2.714, P = 0.013) and preoperative mRS score (t = 6.678, P < 0.001) correlated with postoperative neovascularization.

Conclusion

ASL is an effective method for detecting CBF and plays an important role in the long-term follow-up of patients with MMA. Combined cerebral revascularization significantly improves CBF in the operation area both in the short and long terms. Patients with lower preoperative Alberta scores and higher mRS scores were more likely to benefit from combined cerebral revascularization surgery. However, regardless of the type of patient, CBF reconstruction can effectively improve prognosis.

Response of internal carotid artery blood flow velocity to fluid challenge under general anesthesia in pediatric patients with moyamoya disease: A prospective observational study

BACKGROUND

Maintaining cerebral blood flow is important in intraoperative management of moyamoya disease patients.

AIMS

To access changes in the carotid artery blood flow velocity in response to fluid challenge, blood pressure, and cardiac output under general anesthesia in pediatric patients with moyamoya disease.

METHODS

This observational study included pediatric patients with moyamoya disease undergoing general anesthesia for encephaloduroarteriosynangiosis. Each patient underwent an ultrasound assessment thrice as follows: after anesthetic induction (T1), after fluid challenge (10 ml/kg, T2), and at the end of surgery (T3). The primary outcome was the change in the internal carotid artery blood flow velocity after fluid challenge and was assessed using a paired t-test. The secondary outcomes comprised changes in the internal, external, and common carotid artery blood flow peak velocities after fluid challenge and the factors influencing these changes.

RESULTS

We enrolled and analyzed 30 patients with a mean age of 7.2 years. After fluid challenge, the systolic (p = .003) and mean blood pressure (p = .017), stroke volume index (p = .008), and cardiac index (p = .140) were higher than those at T1. However, both internal carotid artery blood flow velocities did not change after fluid challenge (p = .798, mean difference and 95% confidence interval [CI], -1.1 and -10.3 to 8.0 for right, p = .164, mean difference and 95% CI, -5.2 and -12.7 to 2.2 for left). The internal carotid artery blood flow velocity was correlated with the cardiac index, stroke volume index, and mean and diastolic blood pressure, with low significance.

CONCLUSIONS

The internal carotid artery blood flow velocity did not increase in pediatric patients with moyamoya disease under general anesthesia, despite fluid challenge and corresponding changes in the blood pressure and cardiac output. Intraoperative hemodynamic management to improve the cerebral blood flow in these patients requires further investigation.

Identification of moyamoya disease based on cerebral oxygen saturation signals using machine learning methods

Moyamoya is a cerebrovascular disease with a high mortality rate. Early detection and mechanistic studies are necessary. Near-infrared spectroscopy (NIRS) was used to study the signals of the cerebral tissue oxygen saturation index (TOI) and the changes in oxygenated and deoxygenated hemoglobin concentrations (HbO and Hb) in 64 patients with moyamoya disease and 64 healthy volunteers. The wavelet transforms (WT) of TOI, HbO and Hb signals, as well as the wavelet phase coherence (WPCO) of these signals from the left and right frontal lobes of the same subject, were calculated. Features were extracted from the spontaneous oscillations of TOI, HbO and Hb in five physiological activity-related frequency segments. Machine learning models based on support vector machine (SVM), random forest (RF) and extreme gradient boosting (XGBoost) have been built to classify the two groups. For 20-min signals, the 10-fold cross-validation accuracies of SVM, RF and XGBoost were 87%, 85% and 85%, respectively. For 5-min signals, the accuracies of the three methods were 88%, 88% and 84%, respectively. The method proposed in this article has potential for detecting and screening moyamoya with high proficiency. Evaluating the cerebral oxygenation with NIRS shows great potential in screening moyamoya diseases.

Spatially separate cerebral infarction in the posterior cerebral artery territory after combined revascularization of the middle cerebral artery territory in an adult patient with moyamoya disease and fetal-type posterior communicating artery: illustrative case

BACKGROUND

Remote cerebral infarction after combined revascularization of the middle cerebral artery (MCA) territory is rare in patients with moyamoya disease (MMD) with a fetal-type posterior communicating artery (PCoA).

OBSERVATIONS

A 57-year-old woman developed numbness in her right upper limb and transient motor weakness and was diagnosed with MMD. She also had a headache attack and a scintillating scotoma in the right visual field. Preoperative magnetic resonance angiography (MRA) showed stenosis of the left posterior cerebral artery (PCA). Combined revascularization was performed for the left MCA territory. No new neurological deficits were observed for 2 days after the operation, but right hemianopia, alexia, and agraphia appeared on postoperative day (POD) 4. Magnetic resonance imaging showed a new left occipitoparietal lobe infarction, and MRA showed occlusion of the distal left PCA. After that point, the alexia and agraphia gradually improved, but right hemianopia remained at the time of discharge on POD 18.

LESSONS

Cerebral ischemia in the PCA territory may occur after combined revascularization of the MCA territory in patients with fetal-type PCoA. For these cases, a double-barrel bypass or indirect revascularization to induce a slow conversion could be considered on its own as a treatment option.

Paradoxical symptomatic cerebral blood flow decreases after combined revascularization surgery for patients with pediatric moyamoya disease: illustrative case

BACKGROUND

Transient neurological deficits (TNDs) develop after cerebral revascularization in patients with moyamoya disease (MMD). The authors report a rare pediatric MMD case with extensive decreased cerebral blood flow (CBF) and prolonged TNDs after combined revascularization.

OBSERVATIONS

A 9-year-old boy presented with transient left upper limb weakness, and MMD was diagnosed. A right-sided combined surgery was performed. Two years after the surgery, frequent but transient facial (right-sided) and upper limb weakness appeared. The left internal carotid artery terminal stenosis had progressed. Therefore, a left combined revascularization was performed. The patient’s motor aphasia and right upper limb weakness persisted for approximately 10 days after surgery. Magnetic resonance angiography showed that the direct bypass was patent, but extensive decreases in left CBF were observed using single photon emission tomography. With adequate fluid therapy and blood pressure control, the neurological symptoms eventually disappeared, and CBF improved.

LESSONS

The environment of cerebral hemodynamics is heterogeneous after cerebral revascularization for MMD, and the exact mechanism of CBF decreases was not identified. TNDs are significantly associated with the onset of stroke during the early postoperative period. Therefore, appropriate treatment is desired after determining complex cerebral hemodynamics using CBF studies.

Acetazolamide-Challenged Arterial Spin Labeling Detects Augmented Cerebrovascular Reserve After Surgery for Moyamoya

BACKGROUND AND PURPOSE

Cerebrovascular reserve (CVR) inversely correlates with stroke risk in children with Moyamoya disease and may be improved by revascularization surgery. We hypothesized that acetazolamide-challenged arterial spin labeling MR perfusion quantifies augmentation of CVR achieved by revascularization and correlates with currently accepted angiographic scoring criteria.

METHODS

We retrospectively identified pediatric patients with Moyamoya disease or syndrome who received cerebral revascularization at ≤18 years of age between 2012 and 2019 at our institution. Using acetazolamide-challenged arterial spin labeling, we compared postoperative CVR to corresponding preoperative values and to postoperative perfusion outcomes classified by Matsushima grading.

RESULTS

In this cohort, 32 patients (17 males) with Moyamoya underwent 29 direct and 16 indirect extracranial-intracranial bypasses at a median 9.7 years of age (interquartile range, 7.6-15.7). Following revascularization, median CVR increased within the ipsilateral middle cerebral artery territory (6.9 mL/100 g per minute preoperatively versus 16.5 mL/100 g per minute postoperatively, P<0.01). No differences were observed in the ipsilateral anterior cerebral artery (P=0.13) and posterior cerebral artery (P=0.48) territories. Postoperative CVR was higher in the ipsilateral middle cerebral artery territories of patients who achieved Matsushima grade A perfusion, in comparison to those with grades B or C (25.8 versus 17.5 mL, P=0.02). The method of bypass (direct or indirect) did not alter relative increases in CVR (8 versus 3.8 mL/100 g per minute, P=0.7).

CONCLUSIONS

Acetazolamide-challenged arterial spin labeling noninvasively quantifies augmentation of CVR following surgery for Moyamoya disease and syndrome.

Anesthetic Management of Moyamoya Syndrome Secondary to Sickle Cell Anemia

Moyamoya disease (MMD) is caused by stenosis or occlusion of internal carotid artery in brain, thereby reducing its blood supply. To augment blood flow, brain develops abnormal anastomotic vessels with deranged carbon dioxide reactivity and tendency to bleed. Moyamoya syndrome (MMS) is the name given to MMD when the latter results from secondary to some associated disease. Occurrence of MMS secondary to sickle cell anemia (SCA) presents unique challenges to neuroanesthesiologists. Management of various physiological parameters for cerebral revascularization surgery for MMD under general anesthesia necessitates vigilant and balanced control of various physiological variables, as the manipulation of a particular physiological variable for one pathology may adversely impact the same physiological variable for the associated disease, which will result in poor outcome of the patient. Therefore, optimum outcome of MMS is determined by a watchful balancing of various physiological parameters under anesthesia.

Cerebral Pressure Autoregulation in Brain Injury and Disorders-A Review on Monitoring, Management, and Future Directions

The role of cerebral pressure autoregulation (CPA) in brain injury and disorders has gained increased interest. The CPA is often disturbed as a consequence of acute brain injury, which contributes to further brain damage and worse outcome. Specifically, in severe traumatic brain injury, CPA disturbances predict worse clinical outcome and targeting an autoregulatory-oriented optimal cerebral perfusion pressure threshold may improve brain energy metabolism and clinical outcome. In aneurysmal subarachnoid hemorrhage, cerebral vasospasm in combination with distal autoregulatory disturbances precipitate delayed cerebral ischemia. The role of optimal cerebral perfusion pressure targets is less clear in aneurysmal subarachnoid hemorrhage, but high cerebral perfusion pressure targets are generally favorable in the vasospasm phase. In acute ischemia, autoregulatory disturbances may occur and autoregulatory-oriented blood pressure (optimal mean arterial pressure) management reduces the risk of hemorrhagic transformation, brain edema, and unfavorable outcome. In chronic occlusive disease such as moyamoya, the gradual reduction of the cerebral circulation leads to compensatory distal vasodilation and the residual CPA capacity predicts the risk for cerebral ischemia. In spontaneous intracerebral hemorrhage, the role of autoregulatory disturbances is less clear, but CPA disturbances correlate with worse clinical outcome. Also, in community-acquired bacterial meningitis, CPA dysfunction is frequent and correlates with worse clinical outcome, but autoregulatory management is yet to be evaluated. In this review, we discuss the role of CPA in different types of brain injury and disease, the strengths and limitations of the monitoring methods, the potentials of autoregulatory management, and future directions in the field.

The First 24 h Hemodynamic Management in NICU after Revascularization Surgery in Moyamoya Disease

Objective

To evaluate whether hemodynamic factors are risk factors for prognosis in moyamoya disease (MMD).

Materials and Methods

The retrospective study reviewed a single-center MMD cohort in Huashan Hospital from August 2017 to January 2020. Stroke events in 30 days and follow-up modified Rankin Scale (mRS) grade were recorded. Systematic assessments with perioperative mean arterial pressure (MAP), red blood cell (RBC) parameters, and fluid management were also conducted. Logistic regressions were applied to evaluate the predictors of worse outcomes. Data was analyzed using SPSS 24.0.

Results

Admission to neurological intensive care unit (NICU) totalled about 347 after revascularization surgery. The result showed that the higher the postoperative MAP level (favorable group 95.7 ± 11.4 mmHg vs. unfavorable group 103.6 ± 10.4 mmHg, p < 0.001) and the greater the MAP variability (favorable group 0.26 ± 13.2 vs. unfavorable group 7.2 ± 13.5, p = 0.006) were, the higher the patient's follow-up mRS grade was. What is more, a higher early postoperative Hb level also seemed to predict a worse long-term clinical outcome (favorable group 116.9 ± 17.1 g/L vs. unfavorable group 123.7 ± 13.0 g/L, p = 0.03), but the difference disappeared after adjusting sex and age. Logistic regression analyses showed that a higher level of postoperative MAP (β = 0.024, 95% CI (0.004, 0.044), and p = 0.02) within the first 24 h in NICU might be the short-term risk factor. For long-term outcome, a higher level (β = 1.058, 95% CI (1.022, 1.096), and p = 0.001) and a greater variability (β = 30.982, 95% CI (2.112, 454.414), and p = 0.01) of postoperative MAP might be the negative predictors of mRS grade.

Conclusions

The early postoperative hemodynamic management might be extremely critical for patients with MMD. Both high postoperative MAP levels and large MAP variability might affect the prognosis. What is more, we also found that a higher postoperative Hb level might be related with a worse outcome.

Risk factors for postoperative ischemic complications in pediatric moyamoya disease

Background

Ischemic events are the most common postoperative complication in bypass surgery for moyamoya disease (MMD), but the risk factors for pediatric MMD remain unclear. The goal of the study was to investigate the risk factors for postoperative ischemic complications in pediatric MMD patients.

Methods

We retrospectively reviewed a consecutive series of pediatric MMD cases at Beijing Tiantan Hospital, Capital Medical University from June 2010 through June 2019. Preoperative clinical variables and radiographic findings were recorded, and logistic regression analysis was carried out to identify the risk factors for postoperative ischemic events.

Results

A total of 533 operations in 336 patients were included in this study. Postoperative complications occurred after 51 operations (9.6%), including 40/447 indirect bypass procedures, 9/70 direct bypass procedures, and 2/16 combined bypass procedures. Postoperative ischemic events were the most common complication and occurred in 30 patients after 31 procedures (8.9% per patient; 5.8% per operation), including 26/447 indirect bypass procedures, 4/70 direct bypass procedures, and 1/16 combined bypass procedures, and the incidence of these events did not differ significantly between indirect and non-indirect bypass (5.8% vs 5.8%; p = 0.999). Multivariate logistic regression analyses revealed that older age at operation (OR 1.129, 95% CI 1.011–1.260, p = 0.032) and posterior cerebral artery involvement (OR 2.587, 95% CI 1.030–6.496, p = 0.043) were significantly associated with postoperative ischemic events.

Conclusion

We speculate that older age at operation and posterior cerebral artery involvement are risk factors for postoperative ischemic events in pediatric MMD patients.

Development and Validation of a Nomogram to Predict the Individual Future Stroke Risk for Adult Patients With Moyamoya Disease: A Multicenter Retrospective Cohort Study in China

Background: Studies exploring the predictive performance of major risk factors associated with future stroke events are insufficient, and a useful tool to predict individual risk is not available. Therefore, personalized advice for preventing future stroke in patients with moyamoya disease (MMD) cannot provide evidence-based recommendations. The aim of this study was to develop a novel nomogram with reliable validity to predict the individual risk of future stroke for adult MMD patients.

Methods: This study included 450 patients from seven medical centers between January 2013 and December 2018. Follow-ups were performed via clinical visits and/or telephone interviews from initial discharge to December 2019. The cohort was randomly assigned to a training set (2/3, n = 300) for nomogram development and a test set (1/3, n = 150) for external validation. The Kaplan-Meier analyses and receiver operating characteristic (ROC) curves were applied to assess the clinical benefits of this nomogram.

Results: Diabetes mellitus, a family history of MMD, a past history of stroke or transient ischemic attack, clinical manifestation, and treatment were identified as major risk factors via the least absolute shrinkage and selection operator (LASSO) method. A nomogram including these predictors was established via a multivariate Cox regression model, which displayed excellent discrimination [Harrell's concordance index (C-index), 0.85; 95% confidence interval (CI): 0.75–0.96] and calibration. In the external validation, the nomogram was found to have good discrimination (C-index, 0.81; 95% CI: 0.68–0.94) and calibration. In the subgroup analysis, this predictive nomogram also showed great performance in both ischemic-type (C-index, 0.90; 95% CI: 0.77–1.00) and hemorrhagic-type MMD (C-index, 0.72; 95% CI: 0.61–0.83). Furthermore, the nomogram was shown to have potential in clinical practice through Kaplan-Meier analyses and ROC curves.

Conclusions: We developed a novel nomogram incorporating several clinical characteristics with relatively good accuracy, which may have considerable potential for evaluating individual future stroke risk and providing useful management recommendations for adult patients with MMD in clinical practice.

Immediate Postoperative Electroencephalography Monitoring in Pediatric Moyamoya Disease and Syndrome

BACKGROUND

Moyamoya disease and syndrome are progressive steno-occlusive cerebrovascular diseases that manifest clinically with ischemic episodes. There is evidence for the use of electroencephalography (EEG) in preoperative and long-term postoperative evaluation of these patients, as well as in the intraoperative period to monitor for changes correlated with perioperative ischemic events. However, the utility of EEG in the immediate postprocedure time period has not previously been described.

METHODS

We review six patients who underwent pial synangiosis from 2017 to 2019. EEGs from the preoperative, intraoperative, and immediate postoperative period were evaluated, as well as clinical examination changes and subsequent interventions.

RESULTS

Six patients with postoperative EEG monitoring following pial synangiosis were included. EEG data was collected preoperatively, intraoperatively, and continuously postoperatively. Preoperatively, five of six patients had normal background activity on EEG, whereas one of six had hemispheric asymmetry. Three patients had new or worsening hemispheric intracerebral asymmetry on EEG during the immediate postsurgical period. Two of these had no clinical manifestations of ischemia, and one had transient left facial weakness. All three underwent blood pressure augmentation with improvement in the asymmetry on EEG and clinical improvement in the symptomatic patient.

CONCLUSIONS

Although widely accepted as a useful tool during the preoperative and intraoperative periods of evaluation and management of moyamoya disease and syndrome, we propose that the use of continuous EEG in the immediate postoperative period may have potential as a useful adjunct by both detecting early clinical and subclinical intracranial ischemia.

Determining Thresholds for Three Indices of Autoregulation to Identify the Lower Limit of Autoregulation During Cardiac Surgery

OBJECTIVES

Monitoring cerebral autoregulation may help identify the lower limit of autoregulation in individual patients. Mean arterial blood pressure below lower limit of autoregulation appears to be a risk factor for postoperative acute kidney injury. Cerebral autoregulation can be monitored in real time using correlation approaches. However, the precise thresholds for different cerebral autoregulation indexes that identify the lower limit of autoregulation are unknown. We identified thresholds for intact autoregulation in patients during cardiopulmonary bypass surgery and examined the relevance of these thresholds to postoperative acute kidney injury.

DESIGN

A single-center retrospective analysis.

SETTING

Tertiary academic medical center.

PATIENTS

Data from 59 patients was used to determine precise cerebral autoregulation thresholds for identification of the lower limit of autoregulation. These thresholds were validated in a larger cohort of 226 patients.

METHODS AND MAIN RESULTS

Invasive mean arterial blood pressure, cerebral blood flow velocities, regional cortical oxygen saturation, and total hemoglobin were recorded simultaneously. Three cerebral autoregulation indices were calculated, including mean flow index, cerebral oximetry index, and hemoglobin volume index. Cerebral autoregulation curves for the three indices were plotted, and thresholds for each index were used to generate threshold- and index-specific lower limit of autoregulations. A reference lower limit of autoregulation could be identified in 59 patients by plotting cerebral blood flow velocity against mean arterial blood pressure to generate gold-standard Lassen curves. The lower limit of autoregulations defined at each threshold were compared with the gold-standard lower limit of autoregulation determined from Lassen curves. The results identified the following thresholds: mean flow index (0.45), cerebral oximetry index (0.35), and hemoglobin volume index (0.3). We then calculated the product of magnitude and duration of mean arterial blood pressure less than lower limit of autoregulation in a larger cohort of 226 patients. When using the lower limit of autoregulations identified by the optimal thresholds above, mean arterial blood pressure less than lower limit of autoregulation was greater in patients with acute kidney injury than in those without acute kidney injury.

CONCLUSIONS

This study identified thresholds of intact and impaired cerebral autoregulation for three indices and showed that mean arterial blood pressure below lower limit of autoregulation is a risk factor for acute kidney injury after cardiac surgery.

A Retrospective Study of Neurological Complications in Pediatric Patients With Moyamoya Disease Undergoing General Anesthesia

BACKGROUND

Moyamoya disease is a condition with potentially devastating and permanent neurological sequelae. Adequate volume status and blood pressure, tight control of carbon dioxide to achieve normocarbia, and providing postoperative analgesia to prevent hyperventilation are typical goals that are used during anesthetic care in these patients. The purpose of this study was to assess postanesthesia neurological complications in moyamoya patients undergoing general anesthesia for imaging studies and surgical procedures excluding neurosurgical revascularization.

METHODS

We performed a retrospective cohort study examining moyamoya patients who received general anesthesia for imaging studies and nonneurosurgical-revascularization procedures between January 1, 2001 and December 1, 2016 at our quaternary care pediatric hospital. A general anesthetic encounter was excluded if it occurred within 30 days after a revascularization surgery. The electronic medical records of study patients were analyzed for perioperative management, and neurological outcomes within 30 days of an anesthetic were assessed.

RESULTS

A total of 58 patients undergoing 351 anesthesia exposures were included in the study. Three patients experienced neurological complications, which included focal neurological weakness, seizure, and altered mental status. The incidence of complications during anesthesia encounters was 0.85% (3/351) with a 95% confidence interval of 0.28-2.62.

CONCLUSIONS

Over a 16-year period at our hospital, 3 children with moyamoya disease who underwent anesthesia for nonneurosurgical-revascularization purposes demonstrated postanesthesia neurological symptoms. The symptoms were consistent with transient ischemic attacks and all resolved without long-term sequelae.

Beyond Anesthesia Toxicity: Anesthetic Considerations to Lessen the Risk of Neonatal Neurological Injury

Infants who undergo surgical procedures in the first few months of life are at a higher risk of death or subsequent neurodevelopmental abnormalities. Although the pathogenesis of these outcomes is multifactorial, an understanding of the nature and pathogenesis of brain injury in these infants may assist the anesthesiologist in consideration of their day-to-day practice to minimize such risks. This review will summarize the main types of brain injury in preterm and term infants and their key pathways. In addition, the review will address key potential pathogenic pathways that may be modifiable including intraoperative hypotension, hypocapnia, hyperoxia or hypoxia, hypoglycemia, and hyperthermia. Each of these conditions may increase the risk of perioperative neurological injury, but their long-term ramifications are unclear.

Comparison of wavelet and correlation indices of cerebral autoregulation in a pediatric swine model of cardiac arrest

Existing cerebrovascular blood pressure autoregulation metrics have not been translated to clinical care for pediatric cardiac arrest, in part because signal noise causes high index time-variability. We tested whether a wavelet method that uses near-infrared spectroscopy (NIRS) or intracranial pressure (ICP) decreases index variability compared to that of commonly used correlation indices. We also compared whether the methods identify the optimal arterial blood pressure (ABPopt) and lower limit of autoregulation (LLA). 68 piglets were randomized to cardiac arrest or sham procedure with continuous monitoring of cerebral blood flow using laser Doppler, NIRS and ICP. The arterial blood pressure (ABP) was gradually reduced until it dropped to below the LLA. Several autoregulation indices were calculated using correlation and wavelet methods, including the pressure reactivity index (PRx and wPRx), cerebral oximetry index (COx and wCOx), and hemoglobin volume index (HVx and wHVx). Wavelet methodology had less index variability with smaller standard deviations. Both wavelet and correlation methods distinguished functional autoregulation (ABP above LLA) from dysfunctional autoregulation (ABP below the LLA). Both wavelet and correlation methods also identified ABPopt with high agreement. Thus, wavelet methodology using NIRS may offer an accurate vasoreactivity monitoring method with reduced signal noise after pediatric cardiac arrest.

Surgery for Moyamoya Disease in Children

Moyamoya disease is a chronic progressive cerebrovascular occlusive disease of the terminal portion of the internal carotid arteries associated with an acquired abnormal vascular network at the base of the brain, often leading to ischemic or hemorrhagic stroke. Moyamoya disease is a relatively common cause of pediatric stroke with a specific racial and well-identified clinical and imaging phenotype. Moyamoya disease is more prevalent in East Asian countries compared with other geographic regions with a higher incidence of familial cases and clinically more aggressive form. Moyamoya disease is one of the few causes of stroke that is amenable to effective surgical revascularization treatment. There are various surgical options available for revascularization, including the direct, indirect, or combined bypass techniques, each with variable responses. However, due to the heterogeneity of the diseases, different clinical course, geographical variables associated with the disease, and availability of a wide variety of surgical revascularization procedures, optimal selection of a surgical candidate and the surgical technique becomes challenging, particularly in the pediatric population. This brief review presents pertinent literature of clinical options for the diagnosis and surgical treatment of moyamoya disease in children.

Predictors of clinical or cerebral lesion progression in adult moyamoya angiopathy

OBJECTIVE

To identify independent predictors of clinical or cerebral lesion progression in a large sample of adult patients with moyamoya angiopathy (MMA) prior to decisions regarding revascularization surgery.

METHODS

Ninety participants (median age, 37.5 years) were assessed at baseline and followed for a median time of 42.8 months. Incident ischemic and hemorrhagic strokes, death, as well as any incident ischemic and hemorrhagic lesions on MRI were recorded. Multiple demographic, clinical, and cerebral imaging measures at baseline were considered as potential predictors of clinical or cerebral tissue change at follow-up. Data were analyzed based on the Andersen-Gill counting process model, followed by internal validation of the prediction model.

RESULTS

Among multiple potential predictive measures considered in the analysis, Asian origin, a history of TIAs, and a reduction in hemodynamic reserve, as detected by imaging, were found to be significantly associated with an increased risk of combined clinical and imaging events. While the model estimated the risk of clinical or cerebral lesion progression to be approximately 0.5% per year when none of these factors was present, this risk exceeded 20% per year when all factors were present.

CONCLUSION

A simple combination of demographic, clinical, and cerebral perfusion imaging measures may aid in predicting the risk of incident stroke and cerebral lesion progression in adult patients with MMA. These results may help to improve therapeutic decisions and aid in the design of future trials in adults with this rare condition.