Correlation between cognitive impairment and cerebral hemodynamic disturbances on perfusion magnetic resonance imaging in European adults with moyamoya disease

Imaging Assessments and Clinical Significance of Brain Frailty in Moyamoya Disease

BACKGROUND AND PURPOSE

Imaging assessment of brain frailty in ischemic stroke has been extensively studied, while the correlation between brain frailty and Moyamoya disease remains obscure. This study aimed to investigate the imaging characteristics of brain frailty and its clinical applications in Moyamoya disease.

MATERIALS AND METHODS

This study included 60 patients with Moyamoya disease (107 hemispheres). All patients were divided into stroke and nonstroke groups based on clinical symptoms and imaging findings. The modified brain frailty score was adapted to consider 4 imaging signs: white matter hyperintensity, enlargement of perivascular space, old vascular lesions, and cerebral microbleed. The relative CBF of the MCA territory was quantified using pseudocontinuous arterial-spin labeling. Surgical outcome after revascularization surgery was defined by the Matsushima grade.

RESULTS

The relative CBF of the MCA territory decreased as the modified brain frailty score and periventricular white matter hyperintensity grades increased (ρ = -0.22, P = .02; ρ = -0.27, P = .005). Clinically, the modified brain frailty score could identify patients with Moyamoya disease with stroke (OR = 2.00, P = .02). Although the modified brain frailty score showed no predictive value for surgical outcome, basal ganglia enlargement of the perivascular space had a significant correlation with the postoperative Matsushima grade (OR = 1.29, P = .03).

CONCLUSIONS

The modified brain frailty score could reflect a cerebral perfusion deficit and clinical symptoms of Moyamoya disease, and its component basal ganglia enlargement of perivascular space may be a promising marker to predict surgical outcome and thus aid future clinical decision-making.

Neuropsychiatric Symptoms of Moyamoya Disease: Considerations for the Clinician

Neurocognitive impairment in moyamoya disease is common, under recognized, and potentially devastating. The purpose of this paper is to provide an updated overview on this topic for the practicing clinician. We searched PubMed for keywords including cognitive impairment, neurocognitive dysfunction, and neuropsychological recovery in moyamoya disease. We summarized the literature to provide a concise review of the treatment and management of neuropsychiatric symptoms associated with moyamoya disease. Neuropsychiatric sequelae have conventionally been attributed to chronic cerebral hypoperfusion and/or stroke. Cognitive dysfunction in adults with moyamoya disease is most commonly in the form of impaired executive function, whereas intelligence is the predominant impairment in children with moyamoya disease. Pharmacotherapy for treatment of the neuropsychiatric symptoms associated with moyamoya disease is appropriate and can improve quality of life; however, careful consideration is needed to avoid adverse cerebrovascular events. It remains unclear as to whether surgical revascularization improves or stabilizes cognitive performance and outcomes. Additional prospective studies are warranted to better understand the long-term impact of revascularization on cognitive functioning in moyamoya disease.

MRI hypoperfusion as a determinant of cognitive impairment in adults with Moyamoya angiopathy

INTRODUCTION

In Moyamoya angiopathy (MMA), mechanisms underlying cognitive impairment remain debated. We aimed to assess the association of cognitive impairment with the degree and the topography of cerebral hypoperfusion in MMA.

METHODS

A retrospective analysis of neuropsychological and perfusion MRI data from adults with MMA was performed. Ischemic and haemorrhagic lesion masks were created to account for cerebral lesions in the analysis of cerebral perfusion. Whole brain volume of hypoperfused parenchyma was outlined on perfusion maps using different Tmax thresholds from 4 to 12 s. Regional analysis produced mean Tmax values at different regions of interest. Analyses compared perfusion ratios in patients with and without cognitive impairment, with multivariable logistic regression analysis to identify predictive factors.

RESULTS

Cognitive impairment was found in 20/48 (41.7%) patients. Attention/processing speed and memory were equally impaired (24%) followed by executive domain (23%). After adjustment, especially for lesion volume, hypoperfused parenchyma volume outlined by Tmax > 4 s or Tmax > 5 s thresholds was an independent factor of cognitive impairment (OR for Tmax > 4 s = 1.06 [CI 95% 1.008-1.123]) as well as attention/processing speed (OR for Tmax > 4 s = 1.07 [CI 95% 1.003-1.133]) and executive domains (OR for Tmax > 5 s = 1.08 [CI 95% 1.004-1.158]). Regarding cognitive functions, patients with processing speed and flexibility impairment had higher frontal Tmax compared to other ROIs and to patients with normal test scores.

DISCUSSION

Cerebral hypoperfusion emerged as an independent factor of cognitive impairment in MMA particularly in attention/processing speed and executive domains, with a strong contribution of frontal areas.

CONCLUSION

Considering this association, revascularization surgery could improve cognitive impairment.

Health-Related Quality of Life and Neuropsychological Outcome After EC-IC Bypass Revascularization in Adult Patients With Moyamoya Disease

BACKGROUND AND OBJECTIVES

Patients with Moyamoya disease (MMD) have an above-average incidence of neuropsychological impairment and psychiatric comorbidities such as depression. Prevalence and correlation with preoperative imaging findings were identified in previous studies, and a reduced health-related quality of life (HRQOL) has been shown. This study investigates changes in neuropsychological performance and HRQOL after revascularization.

METHODS

Thirty-two adult patients with MMD (23 female, 9 male; mean age 39.1 year ±14.7) with revascularization were included in this retrospective cohort study, and their results of structured neuropsychological testing were analyzed preoperatively and 1 year postoperatively. Sensorimotor deficits assessed with the National Institutes of Health Stroke Scale were considered to be possible confounders.

RESULTS

Patients with preoperatively poor test results showed improvement in various items such as psychological well-being (95% CI [0.55-2.25], P = .002), vitality (95% CI [0.23-1.68], P = .007), general health perception (95% CI [0.09-1.44], P = .014), psychoticism (95% CI [-12.24 to -4.85], P < .001), and psychomotor processing speed (95% CI [0.10-1.14], P = .010), whereas the intensity of depression fell by a mean of 6.9 points (95% CI [-10.14 to -3.61], P < .001). For patients without preoperative neuropsychological or HRQOL deterioration, preservation of these functions without relevant worsening after revascularization was observed. Significant improvement in vitality, psychological well-being, psychoticism, psychomotor processing speed, and depression were also seen in patients with unchanged National Institutes of Health Stroke Scale.

CONCLUSION

Chronic steno-occlusive cerebral hypoperfusion in patients with MMD not only may lead to neurological deficits but is also associated with neuropsychological impairment, reduced HRQOL, and increased depression. The results of this study show that patients with preoperative neuropsychological deterioration might benefit from revascularization surgery, whereas patients without preoperative impairment continue to remain stable postoperatively. Neuropsychological assessment should be routinely evaluated and considered a relevant variable when determining treatment for patients with MMD.

Prevalence and Associations of Cognitive Impairment in Adult Patients with Moyamoya Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Cognitive impairment, and in the long term Alzheimer's disease, vascular, or mixed dementia, are potential complications of moyamoya disease (MMD), of which the prevalence and associations are not well established.

OBJECTIVE

We performed a systematic review and meta-analysis to investigate the prevalence of cognitive impairment in adult patients with MMD as well as its clinical and demographic correlates.

METHODS

We performed a systematic search of four electronic databases: PubMed (MEDLINE), EMBASE, Scopus, and Cochrane Library, profiling studies from inception until 7 May 2023. Clinical data consisting of population characteristics, comorbidities, cognitive assessment tools used, and prevalence of cognitive impairment was extracted.

RESULTS

Seventeen studies were included in the meta-analysis, with a total study population of 1,190 patients. All studies assessed cognition, and the overall prevalence of cognitive impairment in MMD patients was 54.59%. A subgroup analysis identified that the prevalence of executive dysfunction in MMD patients was 31.55%. We performed a meta-regression analysis which identified that cognitive impairment was not associated with age, education level, or a history of ischemic or hemorrhagic stroke.

CONCLUSIONS

A substantial proportion of MMD patients have cognitive impairment, and cognitive impairment was found to have no association with a history of stroke. Further research is necessary to investigate the longitudinal relationship of MMD and cognitive impairment, and the impact of bypass surgery on cognitive impairment.

Long-term study of the cognitive profile of Moyamoya Disease in adults

Moyamoya Disease (MMD) is a rare cerebrovascular disorder which can have significant cognitive consequences. The aim of the current study was to describe comprehensively the domain-specific cognitive profile of adult patients with MMD and to assess whether this changes in the absence of recurrent stroke over long-term follow-up. Comprehensive neuropsychological assessment covering seven cognitive domains was conducted on 61 adult patients with MMD at baseline and then at up to 3 further time points during follow up (median=2.31, 4.87 and 7.12 years). Although 27 patients had had prior surgical revasculariation, none had surgery between neuropsychological assessments. Cognitive impairment was common. At baseline, impairment in executive functions was most frequent (57%), followed by performance IQ (36%), speed of information processing (31%) and visual memory (30%). We found that the neuropsychological profile remains broadly stable over long-term follow-up with no clear indication of improvement or significant decline. The pattern of impairment also did not differ depending on age of onset or whether there was a history of either prior stroke at presentation or revascularisation surgery at presentation.

Association of cognitive function and hypoperfusion in Moyamoya disease patients without stroke

The influence of hypoperfusion on cognition in patients with Moyamoya disease (MMD) is unclear. This study investigated cognitive function changes in MMD patients without stroke and illustrated the relationship between cognitive impairment and hypoperfusion. We prospectively performed a structured battery of seven neurocognitive tests on 115 adult MMD patients without stroke and 82 healthy controls. Hemodynamic assessment was performed using dynamic susceptibility contrast-enhanced MRI. The best subset regression (BSR) strategy was used to identify risk factors. Global cognition (MoCA), speed of information processing (TMT-A), executive function (TMT-B), visuospatial function (CDT), and verbal memory (CAVLT) were significantly poorer in MMD patients without stroke than in healthy controls. The TMT-B score significantly correlated with cerebral blood flow (CBF) in the bilateral lateral frontal lobes, centrum semiovale, and temporal lobes. The TMT-A and CAVLT scores significantly correlated with CBF in the left centrum semiovale (L-CSO) and temporal lobes. According to the BSR results, age, education, white matter lesions, and hypoperfusion of the L-CSO were risk factors for cognitive impairment. Hypoperfusion leads to multiple cognitive impairments in MMD patients without stroke. The perfusion of particular areas may help evaluate the cognitive function of MMD patients and guide therapeutic strategies.

Association Between Frontal Lobe Hemodynamics and Neurocognitive Dysfunction in Adults With Moyamoya Disease: Retrospective Cohort Analysis

BACKGROUND

Adult patients with moyamoya disease (MMD) may present with mild cognitive dysfunction, even those without evidence of conspicuous brain parenchymal damage. This cognitive dysfunction might be caused by local frontal lobe ischemia.

OBJECTIVE

To explore the relationship between frontal lobe hemodynamic insufficiency and cognitive dysfunction in patients with MMD.

METHODS

Thirty adult patients with MMD without conspicuous brain parenchymal damage were retrospectively examined. Patients with MMD with frontal lobe intracerebral steal phenomenon on single photon emission computed tomography were defined as group S (n = 13) and those without it were defined as group P (n = 17). A comparative group comprising patients with unruptured intracranial aneurysm was defined as group C (n = 30). The results of various cognitive and intelligence tests and a composite cognitive score were compared between groups.

RESULTS

The digit span test forward version ( P = .041), frontal assessment battery ( P = .022), and composite cognitive score ( P = .015) z-scores were significantly lower in group S than group C. Adjusting for sex and age, patients in group S had a significantly lower composite cognitive score compared with those in group C in multiple regression analysis ( P = .037). Executive dysfunction and working memory dysfunction may be involved in the cognitive decline observed in group S.

CONCLUSION

Mild cognitive dysfunction in MMD was associated with frontal lobe hemodynamic insufficiency. Future studies should examine whether revascularization can improve cerebral hypoperfusion and neurocognitive function in these patients.

Two adult patients with moyamoya disease presenting with alexia with agraphia limited to kanji: can revascularization improve characteristic symptoms?

Patients with moyamoya disease (MMD) may exhibit higher brain dysfunction due to hypoperfusion, which may be ameliorated by revascularization. However, few studies have examined the relationship between cerebral perfusion and language function or the ameliorating effect of revascularization on language dysfunction. We present two cases with MMD who presented with alexia with agraphia, specifically for Japanese kanji. The patients had impaired perfusion in the left inferior temporal and lateral occipital lobes. Following superficial temporal artery-middle cerebral artery bypass, the symptoms improved dramatically. Thus, correction of hypoperfusion may be effective even in adult patients with MMD presenting with language dysfunction.

The profile of cognitive impairment and hemodynamic compromise in moyamoya: a single-center prospective cohort study

OBJECTIVE

Patients with moyamoya vasculopathy often experience cognitive impairments. In this prospective single-center study, the authors investigated the profile of neurocognitive impairment and its relation with the severity of ischemic brain lesions and hemodynamic compromise.

METHODS

Patients treated in a Dutch tertiary referral center were prospectively included. All patients underwent standardized neuropsychological evaluation, MRI, digital subtraction angiography, and [15O]H2O-PET (to measure cerebrovascular reactivity [CVR]). The authors determined z-scores for 7 cognitive domains and the proportion of patients with cognitive impairment (z-score < -1.5 SD in at least one domain). The authors explored associations between patient characteristics, imaging and CVR findings, and cognitive scores per domain by using multivariable linear regression and Bayesian regression analysis.

RESULTS

A total of 40 patients (22 children; 75% females) were included. The median age for children was 9 years (range 1-16 years); for adults it was 39 years (range 19-53 years). Thirty patients (75%) had an infarction, and 31 patients (78%) had impaired CVR (steal phenomenon). Six of 7 cognitive domains scored below the population norm. Twenty-nine patients (73%) had cognitive impairment. Adults performed better than children in the cognitive domain visuospatial functioning (p = 0.033, Bayes factor = 4.0), and children performed better in processing speed (p = 0.041, Bayes factor = 3.5). The authors did not find an association between infarction, white matter disease, or CVR and cognitive domains.

CONCLUSIONS

In this Western cohort, cognitive functioning in patients with moyamoya vasculopathy was below the population norm, and 73% had cognitive impairment in at least one domain. The cognitive profile differed between adults and children. The authors could not find an association with imaging findings.

Fronto-Parietal and White Matter Haemodynamics Predict Cognitive Outcome in Children with Moyamoya Independent of Stroke

Moyamoya disease is a major arteriopathy characterised by progressive steno-occlusion of the arteries of the circle of Willis. Studies in adults with moyamoya suggest an association between abnormal fronto-parietal and white matter regional haemodynamics and cognitive impairments, even in the absence of focal infarction. However, these associations have not been investigated in children with moyamoya. We examined the relationship between regional haemodynamics and ratings of intellectual ability and executive function, using hypercapnic challenge blood oxygen level-dependent magnetic resonance imaging of cerebrovascular reactivity in a consecutive cohort of children with confirmed moyamoya. Thirty children were included in the final analysis (mean age: 12.55 ± 3.03 years, 17 females, 15 idiopathic moyamoya and 15 syndromic moyamoya). Frontal haemodynamics were abnormal in all regardless of stroke history and comorbidity, but occipital lobe haemodynamics were also abnormal in children with syndromic moyamoya. Executive function deficits were noted in both idiopathic and syndromic moyamoya, whereas intellectual ability was impaired in syndromic moyamoya, even in the absence of stroke. Analysis of the relative effect of regional abnormal haemodynamics on cognitive outcomes demonstrated that executive dysfunction was predominantly explained by right parietal and white matter haemodynamics independent of stroke and comorbidity, while posterior circulation haemodynamics predicted intellectual ability. These results suggest that parietal and posterior haemodynamics play a compensatory role in overcoming frontal vulnerability and cognitive impairment.

Moyamoya disease: A human model for chronic hypoperfusion and intervention in Alzheimer's disease

Introduction

Chronic cerebral hypoperfusion has been considered the etiology for sporadic Alzheimer's disease (AD). However, no valid clinical evidence exists due to the similar risk factors between cerebrovascular disease and AD.

Methods

We used moyamoya disease (MMD) as a model of chronic hypoperfusion and cognitive impairment, without other etiology interference.

Results

Based on the previous reports and preliminary findings, we hypothesized that chronic cerebral hypoperfusion could be an independent upstream crucial variable, resulting in AD, and induce pathological hallmarks such as amyloid beta peptide and hyperphosphorylated tau accumulation.

Discussion

Timely intervention with revascularisation would help reverse the brain damage with AD hallmarks and lead to cognitive improvement.

Superficial temporal artery lengthening technique to prevent postoperative wound complications in direct revascularization to the anterior cerebral artery for Moyamoya disease

BACKGROUND

Neurocognitive dysfunctions or psychomotor symptoms of Moyamoya disease may improve after direct revascularization to the anterior cerebral artery (ACA). However, long-distance harvest of the frontal branch of the superficial temporal artery (STA) is needed to reach the cortical ACA, frequently resulting in postoperative wound complications. To solve this problem, we devised a novel method (STA lengthening technique). In this study, we compared the STA lengthening technique and the conventional method regarding postoperative wound complications.

METHODS

Twenty-five patients who underwent STA-ACA direct bypass from December 2016 to October 2021 were retrospectively reviewed, and postoperative wound complications were recorded. Magnetic resonance angiography was performed to evaluate the patency of the bypass to the ACA and postoperative development of collaterals to the skin flap.

RESULTS

Thirty-eight hemispheres (new method [n = 12] vs. conventional method [n = 26]) were treated. Wound complications occurred in 12 surgeries (46%) of the conventional method, and none (0%) of the new method. The anastomosis with the cortical ACA was patent in all surgeries. Postoperative development of collaterals to the skin flap was confirmed after all surgeries (100%) in the new method, whereas after only five surgeries (20%) in the conventional method.

CONCLUSION

The STA lengthening technique can enable to preserve the collateral circulation to the skin flap postoperatively, resulting in good wound healing.

Characterizing the neurocognitive profiles of children with moyamoya disease using the Das Naglieri cognitive assessment system

Although cognitive impairment is well-documented in children with moyamoya disease (MMD), selective decline in specific neurocognitive domains remains controversial. The purpose of this study was to characterize the neurocognitive profile of children with MMD using the Das Naglieri Cognitive Assessment System (CAS) and the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV). We analyzed the neurocognitive data of 30 children (median age, 7 years) with MMD who were assessed with the CAS and the WISC-IV before surgery. We focused on the comparison of standard scores and intraindividual differences across domains. The CAS scores significantly varied across four measures (standard scores, p < 0.001; intraindividual differences, p < 0.001). Post-hoc analyses revealed that the standard scores and intraindividual differences for successive processing were significantly lower than those for planning and attention. The WISC-IV scores did not significantly vary among the four measures, although the working memory index was the lowest among the four measures. The within-individual weakness in successive processing, a form of working memory function, may be a distinct characteristic of children with MMD. The CAS may be more sensitive than the WISC-IV for detecting this selective neurocognitive weakness in children with MMD.

Neurocognitive Profiles of Caucasian Moyamoya Disease Patients in Greece: A Case Series

The impact of Moyamoya Disease (MMD) on cognition inadult Caucasian patients has not yet been thoroughly investigated. The current study is the first to present detailed neuropsychological data on a series of Greek patients with MMD. A group of eight patients was assessed with an extensive neuropsychological battery, including measures of episodic memory, working memory, executive functions, language, and social cognition. The results indicated that MMD may be characterized by a trichotomous neurocognitive profile, characterized by prominent impairment in working memory, executive functions, and social cognition. Overall, we stress the need for a thorough cognitive evaluation of MMD patients and further highlight the potential importance of social cognition in this particular disease. Possible associations between the three impaired cognitive domains in our group are also discussed.

Specific learning disorder in mathematics and moyamoya disease: A case report

Moyamoya disease (MMD) is a rare neurological condition that causes impaired blood flow to the brain, transient ischemic attacks or strokes, and accompanying cognitive impairments, especially in executive functioning. There is little data on the impact of this rare condition on academic outcomes in late childhood and adolescence. Here, we present the case of Ms. X, a 17-year-old white female diagnosed with MMD, who presented with evidence of a specific learning disorder (SLD) in mathematics. Ms. X was diagnosed with MMD at 6 years old and underwent revascularization surgery. Though she recovered well and progressed adequately in home schooling, she and her mother noticed a decline in memory and academic performance around 16 years old, prompting a neuropsychological evaluation. Cognitive testing revealed low average overall cognitive abilities with impaired planning and organizational skills. While her reading and spelling skills were consistent with her 10th grade academic level, she scored in the 1st percentile on the WRAT-5 Math Computation section, and her mathematical skills were estimated to be at a 2nd grade level. This case adds to the literature by documenting a specific area of academic deficit in an adolescent with MMD. The case highlights that individuals with MMD, especially those with similar executive deficits, may experience selective learning challenges in mathematics. Children with MMD may benefit from specialized academic services and interventions in specific areas of difficulty.

Predictors of preoperative cognitive dysfunction in adults with Moyamoya disease: a preliminary research

OBJECTIVE

To explore potential risk factors of preoperative cognitive dysfunction in adult patients with moyamoya disease (MMD) and discuss significance of moyamoya vessels.

METHODS

The author reviewed adult MMD patients harboring no parenchymal infarction or hemorrhage underwent a standardized neuropsychological assessment test battery from December 2018 to May 2019. The authors defined patients with cognitive dysfunction as cognitive impairment shown on 3 or more neuropsychological tests. According to the presence of cerebral angiography, arterial stenosis, moyamoya vessels, and compensatory arteries were conducted. Univariate and multivariate analyses were performed to identify predictors for cognitive dysfunction before surgery. Subgroup analyses by onset type and Suzuki stage were carried out to identify specific predictors for preoperative cognitive dysfunction.

RESULTS

In total, 29 of 92 (31.52%) patients had cognitive dysfunction. Multivariate analysis showed that moyamoya vessels generating from left hemisphere was recognized as independent predictor for cognitive dysfunction (P = 0.025, OR [95%CI], 0.085 [0.012-0.874]). For patients in left ICA-moyamoya subgroup, 19 of 45 (42.22%) cases with sparse moyamoya vessels had cognitive dysfunction (P = 0.031), while 22 (91.67%) of patients with dense moyamoya vessels had normal cognition (P = 0.004). Moyamoya vessels arising from ophthalmic artery had no significant association with cognitive dysfunction (P = 0.111). Multivariate analysis found that moyamoya vessels originating from left ICA was recognized as independent predictors for preoperative cognitive dysfunction (P = 0.048, OR [95%CI], 0.394 [0.132-0.926]).

CONCLUSIONS

Moyamoya vessels arising from left hemisphere was a risk factor for the preoperative cognitive dysfunction in adult patients with MMD, with the denser moyamoya vessels, the less cognitive dysfunction. The current study offers a new perspective of moyamoya vessels and supporting data for choosing MMD candidates on cerebral revascularization.

Revascularization to the ACA: effectiveness and variation of the STA-RAG-A3 bonnet bypass

BACKGROUND

The effectiveness of bypass surgery in patients with atherothrombotic ischemia in the anterior cerebral artery (ACA) domain remains unclear. In this study, three cases with ischemia in the ACA territory underwent revascularization surgery using superficial temporal artery (STA)-radial artery graft (RAG)-A3 (pericallosal artery) bonnet bypass. Herein, we discuss the effectiveness and variations of this approach.

METHODS

Among 182 consecutive patients with atherothrombotic ischemic stroke admitted to the NTT Medical Center, Tokyo, from April 2017 to May 2021, three patients with hemodynamic insufficiency in the extensive ACA territory beyond the recent infarct area were treated using STA-RAG-A3 bonnet bypass.

RESULTS

One patient with bilateral severe cerebral blood flow (CBF) deficiency required additional A3-A3 and STA-middle cerebral artery single bypass in conjunction with STA-RAG-A3 bypass. There were no complications associated with the surgical procedure. The patients' hemodynamic study results and neurocognitive performances improved dramatically after surgery.

CONCLUSION

Our results suggest the efficacy of STA-RAG-A3 bypass for atherothrombotic ACA ischemia. However, because the number of cases was too small to generalize our results, more cases and thorough pre- and postoperative hemodynamic studies are necessary to prove the validity of the approach.

Relationship Between Cerebrovascular Reactivity and Cognition Among People With Risk of Cognitive Decline

Vascular risk factors (e.g., obesity and hypertension) are associated with cerebral small vessel disease, Alzheimer's disease (AD) pathology, and dementia. Reduced perfusion may reflect the impaired ability of blood vessels to regulate blood flow in reaction to varying circumstances such as hypercapnia (increased end-tidal partial pressures of CO₂). It has been shown that cerebrovascular reactivity (CVR) measured with blood-oxygen-level-dependent (BOLD) MRI is correlated with cognitive performance and alterations of CVR may be an indicator of vascular disfunction leading to cognitive decline. However, the underlying mechanism of CVR alterations in BOLD signal may not be straight-forward because BOLD signal is affected by multiple physiological parameters, such as cerebral blood flow (CBF), cerebral blood volume, and oxygen metabolism. Arterial spin labeling (ASL) MRI quantitatively measures blood flow in the brain providing images of local CBF. Therefore, in this study, we measured CBF and its changes using a dynamic ASL technique during a hypercapnia challenge and tested if CBF or CVR was related to cognitive performance using the Mini-mental state examination (MMSE) score. Seventy-eight participants underwent cognitive testing and MRI including ASL during a hypercapnia challenge with a RespirAct computer-controlled gas blender, targeting 10 mmHg higher end-tidal CO₂ level than the baseline while end-tidal O₂ level was maintained. Pseudo-continuous ASL (PCASL) was collected during a 2-min baseline and a 2-min hypercapnic period. CVR was obtained by calculating a percent change of CBF per the end-tidal CO₂ elevation in mmHg between the baseline and the hypercapnic challenge. Multivariate regression analyses demonstrated that baseline resting CBF has no significant relationship with MMSE, while lower CVR in the whole brain gray matter (β = 0.689, p = 0.005) and white matter (β = 0.578, p = 0.016) are related to lower MMSE score. In addition, region of interest (ROI) based analysis showed positive relationships between MMSE score and CVR in 26 out of 122 gray matter ROIs.

Impairments in brain perfusion, executive control network, topological characteristics, and neurocognition in adult patients with asymptomatic Moyamoya disease

Background

Asymptomatic Moyamoya disease (MMD) impairs hemodynamic and cognitive function. The relationship between these changes, cerebral blood flow (CBF), and network connectivity remains largely unknown. The aim of this study was to increase understanding of the relationship between CBF, functional networks, and neurocognition in adults with asymptomatic MMD. We compared CBF and functional status in 26 patients with MMD and 20 healthy controls using arterial spin labeling and resting state functional magnetic resonance imaging sequences. At the same time, a detailed cognitive test was performed in 15 patients with no cerebral or lumen infarction who were selected by magnetic resonance imaging-T2 FLAIR screening.

Results

Compared to the controls, the patients showed varying degrees of decline in their computational ability (simple subtraction, p = 0.009; complex subtraction, p = 0.006) and short-term memory (p = 0.042). The asymptomatic MMD group also showed decreased CBF in the left anterior central and left inferior frontal gyri of the island flap with multiple node abnormalities in the brain network and reduced network connectivity. There was a significant association of these changes with cognitive decline in the MMD group.

Conclusions

In patients with asymptomatic MMD, disturbance of CBF and impaired brain network connections may be important causes of cognitive decline and appear before clinical symptoms.

Clinical trial registration-URL: http://www.chictr.org.cn

Unique identifier: ChiCTR1900023610

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-021-00638-z.

Cerebrovascular Reactivity Measurement Using Magnetic Resonance Imaging: A Systematic Review

Cerebrovascular reactivity (CVR) magnetic resonance imaging (MRI) probes cerebral haemodynamic changes in response to a vasodilatory stimulus. CVR closely relates to the health of the vasculature and is therefore a key parameter for studying cerebrovascular diseases such as stroke, small vessel disease and dementias. MRI allows in vivo measurement of CVR but several different methods have been presented in the literature, differing in pulse sequence, hardware requirements, stimulus and image processing technique. We systematically reviewed publications measuring CVR using MRI up to June 2020, identifying 235 relevant papers. We summarised the acquisition methods, experimental parameters, hardware and CVR quantification approaches used, clinical populations investigated, and corresponding summary CVR measures. CVR was investigated in many pathologies such as steno-occlusive diseases, dementia and small vessel disease and is generally lower in patients than in healthy controls. Blood oxygen level dependent (BOLD) acquisitions with fixed inspired CO₂ gas or end-tidal CO₂ forcing stimulus are the most commonly used methods. General linear modelling of the MRI signal with end-tidal CO₂ as the regressor is the most frequently used method to compute CVR. Our survey of CVR measurement approaches and applications will help researchers to identify good practice and provide objective information to inform the development of future consensus recommendations.

Early Diffusion Magnetic Resonance Imaging Changes in Normal-Appearing Brain in Pediatric Moyamoya Disease

BACKGROUND

Moyamoya disease often leads to ischemic strokes visible on diffusion-weighted imaging (DWI) and T2-weighted magnetic resonance imaging (MRI) with subsequent cognitive impairment. In adults with moyamoya, apparent diffusion coefficient (ADC) is correlated with regions of steal phenomenon and executive dysfunction prior to white matter changes.

OBJECTIVE

To investigate quantitative global diffusion changes in pediatric moyamoya patients prior to explicit structural ischemic damage.

METHODS

We retrospectively reviewed children (<20 yr old) with moyamoya disease and syndrome who underwent bypass surgery at our institution. We identified 29 children with normal structural preoperative MRI and without findings of cortical infarction or chronic white matter ischemic changes. DWI datasets were used to calculate ADC maps for each subject as well as for 60 age-matched healthy controls. Using an atlas-based approach, the cerebral white matter, cerebral cortex, thalamus, caudate, putamen, pallidum, hippocampus, amygdala, nucleus accumbens, and brainstem were segmented in each DWI dataset and used to calculate regional volumes and ADC values.

RESULTS

Multivariate analysis of covariance using the regional ADC and volume values as dependent variables and age and gender as covariates revealed a significant difference between the groups (P < .001). Post hoc analysis demonstrated significantly elevated ADC values for children with moyamoya in the cerebral cortex, white matter, caudate, putamen, and nucleus accumbens. No significant volume differences were found.

CONCLUSION

Prior to having bypass surgery, and in the absence of imaging evidence of ischemic stroke, children with moyamoya exhibit cerebral diffusion changes. These findings could reflect microstructural changes stemming from exhaustion of cerebrovascular reserve.

Different aspects of cognitive function in adult patients with moyamoya disease and its clinical subtypes

Objective

Although a few reports suggested that cognitive function impairment could be found in adult patients with moyamoya disease (MMD), there were still many aspects that are unclear. The aim of our study was to assess the cognitive function of adult patients with MMD and its clinical subtypes.

Methods

49 patients with MMD and 23 healthy controls were asked to take cognitive function tests. Cognitive function tests included IQ, prospective memory (PM), immediate memory (IM), verbal fluency (VF), visual breadth, attention, retrospective memory (RM), Stroop test, Wisconsin Card Sorting Test, Trail-Making Test Part A (TMT-A) and Continuous Performance Test (CPT). Independent t-analysis, one-way analysis of variance and Pearson correlation were used to seek for differences between subgroups and the correlation between cognitive variables.

Results

Compared with healthy controls, adult patients with MMD had a comprehensive cognitive impairment, including IQ, PM, VF, attention, RM, Stroop, CPT and TMT-A, with more serious impairment in PM and attention. PM and RM were separated, indicating that they were independent of each other. Pattern of attention was significantly different from healthy controls. Female patients were better than male patients, where significant differences in PM, IM, Stroop and WCST could be found. The haemorrhagic patients exhibited poorer in the dimension of PM and RM than the ischaemic. The headache subtype exhibited poorer than healthy controls. PM, RM, attention and executive function were moderately correlated with each other.

Conclusions

Adult patients with MMD had a wide range of cognitive impairment with more serious impairment in memory and attention. Differences in cognitive function existed between the different subtypes of adult MMD.

Decreased frontal white-matter diffusion and improved cognitive flexibility after burr-hole surgery in moyamoya angiopathy

BACKGROUND

In Moyamoya Angioplasty (MMA), increased apparent diffusion coefficient (ADC) in frontal white matter (WM) with a normal appearance has been associated with frontal hypoperfusion and executive dysfunction. Multiple burr-hole surgery enables the revascularization of large frontal areas.

GOAL

To assess the effect of multiple burr-hole surgery on the ADC and cognitive functions in adults with MMA.

METHODS

ADC was measured in 26 brain hemispheres of 14 consecutive adults with MMA (9 women, mean age ± SD: 38.1 ± 10.7 years) prior to and 6 months after burr-hole surgery. ADC was obtained from regions of interest located in frontal and posterior (temporo-occipital) normal-appearing WM. Ten patients had neuropsychological assessment that focused on executive and attentional functions before and after surgery.

RESULTS

Anterior and posterior ADC values did not differ before surgery (815.8 ± 60.1 vs. 812.1 ± 35.3 mm²/s, p = 0.88). After surgery, frontal ADC was lower than prior to surgery (789.9 ± 64.5 vs. 815.8 ± 60.1 mm²/s; p <0.001) whereas no change occurred in posterior ADC (p = 0.31). Trail-making test part B median z-score increased from - 1.47 to - 0.21 (p = 0.018), suggesting improved cognitive flexibility.

CONCLUSION

In adults with MMA, indirect revascularization with burr-hole is followed by a decrease of ADC in normal-appearing frontal WM and may have improved some executive functions in the flexibility process. Change in ADC may reflect the improvement in cerebral perfusion after surgery. The measuring of ADC may be a promising tool in exploring potentially reversible microstructural WM damage related to hypoperfusion and cognitive change in MMA.

Cognitive Performance Profile in Pediatric Moyamoya Disease Patients and Its Relationship With Regional Cerebral Blood Perfusion

Object: Moyamoya disease affects the cognitive function of pediatric patients, and compromised cerebral blood flow might be the potential cause. We aimed to explore the specific correlation between cognitive impairment and regional perfusion status in pediatric moyamoya disease patients.

Methods: We prospectively enrolled consecutive pediatric moyamoya disease patients admitted to Beijing Tiantan Hospital from July 2017 to March 2019. Arterial spin-labeling magnetic resonance and the Wechsler Intelligence Scale for Children (the 4th edition) were performed on all participants. The cognitive performance of patients was analyzed, and its correlation to cerebral perfusion status was also investigated in the region of interest-based analysis.

Results: A total of 21 patients met the inclusion criteria (mean aged 11.14 ± 2.82, male: female = 11:10). Six patients (28.6%) showed no cognitive deficits in any index score, while 15 (71.4%) showed cognitive deficits with differing severity. Nine (42.9%) patients showed overall cognitive impairment, and all cognitive index scores except for Verbal Comprehension Index were significantly lower than the mean scores of normative data with corresponding age. Perceptual Reasoning Index (p = 0.019) were statistically lower in patients with radiologically confirmed cerebral infarction. Suzuki stage of the left hemisphere negatively correlated to Full-scale Intelligence Quotient (r = −0.452, p = 0.039). Region of Interest analysis showed that cerebral blood flow of the left temporal lobe independently associated with the Processing Speed Index (β = 0.535, p = 0.041).

Conclusion: Pediatric moyamoya disease patients exhibited different levels of cognitive impairment. Cerebral infarction is related to poorer perceptual reasoning ability. Cerebral blood flow in the left temporal lobe positively correlates with processing speed.

Neuropsychological impairment in adults with moyamoya angiopathy: preoperative assessment and correlation to MRI and H215O PET

Patients with moyamoya angiopathy (MMA) are known to have an increased risk of impaired executive function (dysexecutive cognitive syndrome (DCS)). Numbers of moyamoya patients with DCS vary strongly in the literature; evidence of a correlation to affected vascular territories is low. This study aims to identify cognitive impairment in adult moyamoya patients and to correlate findings with imaging results. In addition, the predictive value of individual tests for the identification of DCS was analyzed. Neuropsychological test data of 41 adult moyamoya patients was analyzed for a possible correlation with territorial hypoperfusion on H₂¹⁵O PET with acetazolamide (ACZ) challenge (cerebrovascular reserve-CVR) and infarction patterns observed in MRI. Each vascular territory was analyzed separately and correlated to neuropsychological test results and to the presence of DCS. In total, 41.5% of patients presented with DCS. Significant association of DCS and affection of the right middle cerebral artery (MCA) territory was seen for insufficient CVR in PET (p = 0.030) and for patients with infarctions seen in MRI (p = 0.014). Analysis of individual neuropsychological test results confirmed the main association with the right MCA territory, as well as some association with the right anterior cerebral artery (ACA) territory. Analysis of a subgroup of patients with chronic disease on MRI (presence of large post-infarction gliosis and brain atrophy in affected territories) revealed a significantly higher risk for DCS (85% affected) than non-chronic patients (21% affected) (p < 0.001). Analysis of neuropsychological test data in this moyamoya cohort reveals DCS in 41.5% of all patients. Correlation between DCS and an impairment of CVR seen in PET and/or infarctions seen in MRI was significant for the right MCA territory. Patients with chronic disease had a significantly higher risk for DCS than non-chronic patients (p < 0.001).

Association of cognitive function with cerebral blood flow in children with moyamoya disease

OBJECTIVE

The cognitive effects of main cerebral artery occlusive lesions are unclear in children with moyamoya disease (MMD). The authors aimed to investigate cognitive function in the presurgical phase of pediatric patients with MMD with no apparent brain lesions.

METHODS

In this prospective, observational, single-center study, 21 children (mean age 10 ± 3.0 years, range 5-14 years) diagnosed with MMD at Hokkaido University Hospital between 2012 and 2018 were enrolled. A cross-sectional evaluation of intellectual ability was performed using the Wechsler Intelligence Scale for Children-Fourth Edition at the initial diagnosis. rCBF was measured using [123I] N-isopropyl p-iodoamphetamine/SPECT. The associations among clinical factors, disease severity, regional cerebral blood flow (rCBF), and intelligence test scores were also examined.

RESULTS

The mean full-scale intelligence quotient (FIQ) was 101.8 ± 12.5 (range 76-125) in children with no apparent brain lesions. A significant difference in the intelligence scale index score was observed, most frequently (42.9%) between working memory index (WMI) and verbal comprehension index (VCI; VCI - WMI > 11 points). Regional CBF was significantly reduced both in the left and right medial frontal cortices (left: 61.3 ± 5.3 ml/100 g/min, right 65.3 ± 5.3 ml/100 g/min; p < 0.001) compared to the cerebellum (77.8 ± 6.8 ml/100 g/min). There was a significant association of rCBF in the left dorsolateral prefrontal cortex (DLPFC) with FIQ (r = 0.46, p = 0.034), perceptual reasoning index (PRI; r = 0.44, p = 0.045), and processing speed index (PSI; r = 0.44, p = 0.045). There was an association between rCBF of the left medial frontal cortex and PSI (r = 0.49, p = 0.026). Age of onset, family history, ischemic symptoms, and angiographic severity were not associated with poor cognitive performance.

CONCLUSIONS

Although average intellectual ability was not reduced in children with MMD, the association of reduced rCBF in the left DLPFC and medial frontal cortex with FIQ, PRI, and PSI suggests mild cognitive dysfunction due to cerebral hypoperfusion.

Reduced arterial compliance along the cerebrovascular tree predicts cognitive slowing in multiple sclerosis: Evidence for a neurovascular uncoupling hypothesis

BACKGROUND

Cognitive slowing occurs in ~70% of multiple sclerosis (MS) patients. The pathophysiology of this slowing is unknown. Neurovascular coupling, acute localized blood flow increases following neural activity, is essential for efficient cognition. Loss of vascular compliance along the cerebrovascular tree would result in suboptimal vasodilation, neurovascular uncoupling, and cognitive slowing.

OBJECTIVE

To assess vascular compliance along the cerebrovascular tree and its relationship to MS-related cognition.

METHODS

We tested vascular compliance along the cerebrovascular tree by dividing cerebral cortex into nested layers. MS patients and healthy controls were scanned using a dual-echo functional magnetic resonance imaging (fMRI) sequence while they periodically inhaled room air and hypercapnic gas mixture. Cerebrovascular reactivity was calculated from both cerebral blood flow (arterial) and blood-oxygen-level-dependent signal (venous) increases per unit increase in end-tidal CO₂.

RESULTS

Arterial cerebrovascular reactivity changes along the cerebrovascular tree were reduced in cognitively slow MS compared to cognitively normal MS and healthy controls. These changes were fit to exponential functions, the decay constant (arterial compliance index; ACI) of which was associated with individual subjects' reaction time and predicted reaction time after controlling for disease processes.

CONCLUSION

Such associations suggest prospects for utility of ACI in predicting future cognitive disturbances, monitoring cognitive deficiencies and therapeutic responses, and implicates neurovascular uncoupling as a mechanism of cognitive slowing in MS.

Pedicled temporoparietal fascial flap for combined revascularization in adult moyamoya disease

Moyamoya disease (MMD) is a progressive, idiopathic cerebrovascular occlusive disease. Various revascularization techniques including direct, indirect, and combined microvascular bypasses have been described. This article presents a modified revascularization technique for MMD utilizing a pedicled temporoparietal fascial flap (TPFF) for combined revascularization. This technique combines a large area of coverage for indirect revascularization with the benefits of a direct bypass. The pedicled TPFF also benefits from intact venous drainage to minimize the risk of flap swelling that could result in complications from mass effect.

Cognitive Functions in Children and Adults with Moyamoya Vasculopathy: A Systematic Review and Meta-Analysis

Background and Purpose

Patients with moyamoya vasculopathy (MMV) may experience cognitive impairment, but its reported frequency, severity, and nature vary. In a systematic review and metaanalysis, we aimed to assess the presence, severity, and nature of cognitive impairments in children and adults with MMV.

Methods

We followed the MOOSE guidelines for meta-analysis and systematic reviews of observational studies. We searched Ovid Medline and Embase for studies published between January 1, 1969 and October 4, 2016. Independent reviewers extracted data for mean intelligence quotient (IQ) and standardized z-scores for cognitive tests, and determined percentages of children and adults with cognitive deficits, before and after conservative or surgical treatment. We explored associations between summary measures of study characteristics and cognitive impairments by linear regression analysis.

Results

We included 17 studies (11 studies reporting on 281 children, six on 153 adults). In children, the median percentage with impaired cognition was 30% (range, 13% to 67%); median IQ was 98 (range, 71 to 107). Median z-score was –0.39 for memory, and –0.43 for processing speed. In adults, the median percentage with impaired cognition was 31% (range, 0% to 69%); median IQ was 95 (range, 94 to 99). Median z-scores of cognitive domains were between –0.9 and –0.4, with multiple domains being affected. We could not identify determinants of cognitive impairment.

Conclusions

A large proportion of children and adults with MMV have cognitive impairment, with modest to large deficits across various cognitive domains. Further studies should investigate determinants of cognitive deficits and deterioration, and the influence of revascularization treatment on cognitive functioning.

When and why is surgical revascularization indicated for the treatment of moyamoya syndrome in patients with RASopathies? A systematic review of the literature and a single institute experience

BACKGROUND

Moyamoya disease (MMD) is a cerebrovascular disorder characterized by the progressive occlusion of the supraclinoid internal carotid artery (ICA), resulting in the formation of an abnormal cerebral vascular network. When MMD occurs in association with an underlying medical condition, including some distinctive genetic disorders, it is named moyamoya syndrome (MMS). The discrimination between MMD and MMS has been validated by recent genetic researches and international reviews. Similarly to patients suffering from MMD, patients with MMS generally become symptomatic because of ischemic complications, which lead to hemiparesis, transient ischemic events, seizures, and sensory symptoms. RASopathies are a group of neurodevelopmental disorders that can be associated with MMS.

RESULTS

We retrospectively reviewed 18 RASopathy patients with MMS treated at our institution from 2000 to 2015 (16 neurofibromatosis type 1, 1 Costello syndrome, and 1 Schimmelpenning syndrome). Here, we report clinical data, performed surgical procedures, and clinic-radiological outcome of these patients. Most of them received both indirect revascularization and medical therapy.

CONCLUSIONS

At the moment, there are no univocal recommendations on which of these two treatment strategies is the treatment of choice in patients with RASopathies and MMS. We suggest that patients with a good overall prognosis (primarily depending on the distinctive underlying genetic disorder) and initial cerebrovascular disease could benefit from a prophylactic surgical revascularization, in order to prevent the cognitive impairment due to the progression of the vasculopathy.

Late Cerebrovascular Events and Social Outcome after Adolescence: Long-term Outcome of Pediatric Moyamoya Disease

In this article, the authors review the literature related to long-term outcome of pediatric moyamoya disease, focusing on late cerebrovascular events and social outcome of pediatric patients once they reach adulthood. Late-onset de novo hemorrhage is rare but more serious than recurrence of ischemic stroke. Long-term follow-up data on Asian populations suggest that the incidence of de novo hemorrhage might increase at age 20 or later, even more than 10 years after bypass surgery. Social adaptation difficulty, possibly related to cognitive impairment caused by frontal ischemia, continues in 10-20% of patients after they reach adulthood, even if no significant disability is present in daily life. A treatment strategy aimed at improving long-term outcome and careful follow-up might be required.

Magnetic resonance imaging for assessment of cerebrovascular reactivity and its relationship to cognition: a systematic review

BACKGROUND

Cerebrovascular reactivity (CVR) refers to the responsiveness of cerebral vasculature to vasoactive stimuli. CVR is an indicator of brain health and can be assessed using vasodilatory techniques and magnetic resonance imaging (MRI). Using such approaches, some researchers have explored the relationship between CVR and cognition; here we systematically review this work.

RESULTS

We extracted information pertaining to: (1) study location and design, participant characteristics, sample sizes, (2) design of vascular challenge, end-tidal CO 2 (etCO 2 ) concentrations (if applicable), (3) MRI protocol, (4) cognitive assessment, (5) CVR values, and outcomes of statistical analyses with cognitive tests. Five studies assessed participants with cognitive impairment compared to controls, one studied patients with multiple sclerosis with or without cognitive impairment compared to controls, one examined patients with moyamoya disease with or without cognitive impairment, two investigated patients with Type 2 diabetes mellitus (T2DM), and one was a cross-sectional study with younger and older healthy adults. Cognition was typically probed using the MMSE and tests of executive function, while a number of vasodilatory techniques were employed.

CONCLUSION

CVR was associated with cognition in six of ten studies, but heterogeneity of study samples, designs and vasodilatory methods may have a role in the inconsistent findings. We make recommendations for future research that includes use of a multi-domain cognitive assessment and standardised hypercapnic challenge with MRI.

Aberrant regional homogeneity of resting-state executive control, default mode, and salience networks in adult patients with moyamoya disease

Aberrant local connectivity within cerebral intrinsic connectivity networks (ICNs) at rest has not been reported in adult moyamoya disease (MMD). Our aim was to examine the regional homogeneity (ReHo) of executive control (ECN), default mode (DMN), and salience networks (SN) in patients with executive dysfunction to explore the underlying mechanism. Twenty-six adult patients with MMD and 24 normal control (NC) subjects were recruited. Executive function was evaluated by Trail Making Test Part B (TMT-B) and executive subtests of Memory and Executive Screening (MES-EX). Compared with NC, the case group exhibited ReHo decrease mainly in the frontal and parietal gyrus, and increase only in the left middle temporal gyrus. Subsequent ICNs analysis indicated that compared with NC, patients with MMD exhibited significantly decreased ReHo in the dorsolateral prefrontal cortex (DLPFC) and inferior parietal gyrus (IPG) of left ECN; the IPG, superior frontal gyrus, and DLPFC of the right ECN; the right precuneus, left medial superior frontal gyrus, and right medial orbitofrontal gyrus of the DMN; as well as the left middle frontal gyrus and right supplemental motor area of SN. When referring to the Suzuki's 6-stage classification, a trend of ReHo decrease with disease severity was observed in all of the ICNs examined, but only bilateral ECNs reached statistical significance. Finally, only bilateral ECNs exhibited a significant correlation of averaged ReHo values with executive performance. Our results provide new insight into the pathophysiology of adult MMD.

Cerebral hemodynamics in orthostatic intolerance with normal head-up tilt test

OBJECTIVES

Orthostatic hypotension (OH) and postural orthostatic tachycardia syndrome (POTS) are well-known causes of orthostatic intolerance (OI). In addition, there are OI patients who are characterized by the symptoms of OI and lack of abnormal findings in head-up tilt (HUT) test. The aim of this study was to determine the cerebral hemodynamic changes in HUT test of OI patients with normal HUT (OINH).

MATERIALS AND METHODS

Two hundred and sixty-one OI patients and 50 healthy controls were enrolled in this study. All subjects underwent transcranial Doppler test while performing the HUT test. Forty-five patients had OH, 33 patients had POTS, and 183 patients had OINH. Blood pressures, heart rate, cerebral blood flow velocities (CBFVs), end-tidal carbon dioxide (ET-PCO2 ), cerebral critical closing pressure (CCP), cerebral perfusion pressure (CPP), and cerebral vascular resistance (CVR) were measured during HUT test. We compared the hemodynamic parameters of OINH with those of OH, POTS, and healthy controls.

RESULTS

Reduced CBFVs, CPP, and ET-PCO2 and elevated CCP were observed in the HUT test of all four groups. CVR was reduced in three OI patients. The drops in systolic CBFV, CPP, and CVR of OINH patients were greater than those of healthy controls. The changes in parameters in the HUT test of OINH group were not different from those of OH and POTS groups except prominent decrements of CPP and CVR in OH group.

CONCLUSION

Our findings suggest that OINH is true OI sharing the common pathomechanism of OH and POTS.

Postoperative executive function in adult moyamoya disease: a preliminary study of its functional anatomy and behavioral correlates

OBJECTIVE Chronic frontal hemodynamic disturbances are associated with executive dysfunction in adult patients with moyamoya disease (MMD). However, the impact of surgical revascularization on executive dysfunction and its underlying mechanism remains unclear. The aim of the present study was to examine the postoperative radiological correlates of cognitive improvement and thereby explore its underlying mechanism. METHODS Fourteen patients who met the inclusion criteria were identified at Huashan Hospital, were operated on, and were successfully followed up for 6 months. Postoperative changes in cortical perfusion and regional amplitude of low-frequency fluctuations (ALFF) were examined by SPECT and resting-state functional MRI, respectively. Executive function was evaluated by 2 tests (Trail Making Test Part B and the summation of executive subtests of Memory and Executive Screening [MES-EX]). Follow-up neuropsychological outcomes were then correlated with radiological changes to identify nodes functioning as leading contributors to postoperative executive outcomes. RESULTS All patients underwent successful unilateral bypass procedures, with some operations performed on the left side and some on the right side. At the 6-month follow-up, the baseline and follow-up test scores for the different sides did not differ significantly. The group with good collaterals (Matsushima Grade A, 9 patients) exhibited significantly increased postoperative perfusion (change in [△] hemodynamics) in bilateral frontal (left, p = 0.009; right, p = 0.003) and left parietal lobe (p = 0.014). The Spearman's correlation test suggested that only the right frontal lobe exhibited significant positive postoperative radiological correlates with cognitive performance (△MES-EX vs △hemodynamics, r = 0.620, p = 0.018; △MES-EX vs △ALFF, r = 0.676, p = 0.008; △hemodynamics vs △ALFF, r = 0.547, p = 0.043). Subsequent regional ALFF analysis revealed that the right dorsolateral prefrontal cortex (DLPFC) was the only node in the responsible hemisphere to exhibit significant postoperative changes. CONCLUSIONS The results not only advance our understanding of pathological interactions of postoperative executive performance in adult MMD, but also indicate that the right DLPFC amplitude might be a quantitative predictor of postoperative executive control improvement.

Different aspects of dysexecutive syndrome in patients with moyamoya disease and its clinical subtypes

OBJECTIVE Dysexecutive syndrome is common in patients with moyamoya disease (MMD), a chronic cerebrovascular disease that is characterized by stenosis of the bilateral internal carotid arteries and progressive collateral revascularization, and MMD can be classified as ischemic or hemorrhagic according to the disease presentation and history. In this study, the authors aimed to determine which aspects of executive function are impaired in patients with MMD, in addition to the specific dysexecutive functions present among its clinical subtypes and the mechanisms underlying dysexecutive function in these patients. METHODS The authors administered 5 typical executive function tests (the Stroop test, the Hayling Sentence Completion Test [HSCT], the verbal fluency [VF] test, the N-back test, and the Sustained Attention to Response Task [SART]) to 49 patients with MMD and 47 IQ-, age-, education-, and social status-matched healthy controls. The dysexecutive questionnaire (DEX) was also used to assess participants' subjective feelings about their executive function. A total of 39 of the patients were evaluated by CT perfusion (CTP) before the assessments were performed, and the correlations among the performances of the patients on the above tests with the parameters of cerebral blood volume, cerebral blood flow (CBF), mean transit time (MTT), and time-to-peak (TTP) in the frontal lobes of these patients were also analyzed. RESULTS Many aspects of executive function in the patients with MMD were significantly poorer than those in the healthy controls, and the patients performed particularly poorer on the VF test, HSCT, N-back test, and SART. The patients with hemorrhagic MMD exhibited worse executive inhibition, executive processing, and semantic inhibition compared with those with ischemic MMD, but the latter group presented a worse working memory and poorer sustained attention. There were no significant differences in the DEX scores between the patients with MMD and healthy controls. The other findings were as follows: CBF was significantly positively correlated with the number correct on part B of the HSCT (r = 0.481, p = 0.01) and accuracy on the 0-back task of the N-back (r = 0.346, p = 0.031); MTT was significantly positively correlated with accuracy on the 2-back task of the N-back (r = 0.349, p = 0.034) and factor 5 of the DEX (r = 0.359, p = 0.032); and TTP was significantly positively correlated with the number correct on part B of the HSCT (r = 0.402, p = 0.034) and the 1-back reaction time of the N-back (r = 0.356, p = 0.026). CONCLUSIONS The patients with MMD exhibited impairments in semantic inhibition, executive processing, working memory, and sustained attention, but they were not aware of these deficits. Moreover, differences in dysexecutive function existed between the different subtypes of MMD. Hypoperfusion of the frontal lobe may be related to working memory and semantic inhibition impairments in patients with MMD.

Chronic ischemia alters brain microstructural integrity and cognitive performance in adult moyamoya disease

BACKGROUND AND PURPOSE

The mechanisms underlying frontal lobe dysfunction in moyamoya disease (MMD) are unknown. We aimed to determine whether chronic ischemia induces subtle microstructural brain changes in adult MMD and evaluated the association of changes with neuropsychological performance.

METHODS

MRI, including 3-dimensional T1-weighted imaging and diffusion tensor imaging, was performed in 23 adult patients with MMD and 23 age-matched controls and gray matter density and major diffusion tensor imaging indices were compared between them; any alterations in the patients were tested for associations with age, ischemic symptoms, hemodynamic compromise, and neuropsychological performance.

RESULTS

Decrease in gray matter density, associated with hemodynamic compromise (P<0.05), was observed in the posterior cingulate cortex of patients with MMD. Widespread reduction in fractional anisotropy and increases in radial diffusivity and mean diffusivity in some areas were also observed in bilateral cerebral white matter. The fractional anisotropy (r=0.54; P<0.0001) and radial diffusivity (r=-0.41; P<0.01) of white matter significantly associated with gray matter density of the cingulate cortex. The mean fractional anisotropy of the white matter tracts of the lateral prefrontal, cingulate, and inferior parietal regions were significantly associated with processing speed, executive function/attention, and working memory.

CONCLUSIONS

In adult MMD, there were more white matter abnormalities than gray matter changes. Disruption of white matter may play a pivotal role in the development of cognitive dysfunction.

A3-A3 anastomosis and superficial temporal artery-radial artery graft-A3 bypass to treat bilateral ACA steno-occlusive hemodynamic ischemia with cognitive and executive dysfunction: a technical note

BACKGROUND

Executive functions are complex cognitive control functions that include cognitive flexibility, inhibition (self-control, self-regulation), and working memory. Bilateral frontal lobe ischemia is associated with cognitive impairment, especially in the context of dysexecutive syndrome. This report describes two patients who underwent bilateral anterior cerebral artery (ACA) reconstruction by A3-A3 anastomosis in conjunction with superficial temporal artery (STA)-radial artery (RA) graft-A3 bypass to treat bilateral ACA steno-occlusive hemodynamic ischemia accompanying cognitive and executive dysfunction.

METHOD

A 74-year-old woman and a 73-year-old woman were admitted to our hospital for unilateral cerebral infarction in the frontal lobe. Magnetic resonance angiogram (MRA) demonstrated severe bilateral ACA steno-occlusive pathology in both patients. Considering the presence of impaired cognitive function with dysexecutive syndrome as well as hemodynamic compromise shown by single photon emission computed tomography (SPECT), we proceeded with A3-A3 anastomosis in conjunction with STA-RA-A3 bypass. Various neuropsychiatric tests were performed before and after the surgery.

RESULTS

We confirmed good bypass patency without periprocedural complications. One patient recovered from apallic and bedridden status and regained ambulatory condition and ability to take in an oral diet. Another patient demonstrated improved scores in several cognitive tests with some persistent executive dysfunction.

CONCLUSIONS

Bilateral ACA revascularization was technically feasible in two patients. This bypass surgery could have some positive effects in some basic cognitive function, such as memory, attention, and concentration by bilateral ACA hemodynamic improvement, although executive function, which is specific to prefrontal function, might not be reversible.

Preliminary study of neurocognitive dysfunction in adult moyamoya disease and improvement after superficial temporal artery-middle cerebral artery bypass

OBJECTIVE

Moyamoya disease (MMD) is a chronic cerebrovascular occlusive disease of unknown etiology. In addition, the neurocognitive impairment of adults with MMD is infrequently reported and, to date, has not been well described. We attempted to determine both the neurocognitive profile of adult moyamoya disease and whether a superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis can improve the neurocognitive impairment in exhibiting hemodynamic disturbance without stroke.

METHODS

From September 2010 through November 2012, 12 patients with angiographically diagnosed MMD underwent STA-MCA anastomosis for hemodynamic impairment. Patients with hypoperfusion and impaired cerebrovascular reserve (CVR) capacity but without evidence of ischemic stroke underwent a cognitive function test, the Seoul Neuropsychological Screening Battery (SNSB). Five patients agreed to undergo a follow-up SNSB test. Data from preoperative and postoperative neurocognitive function tests were compared and analyzed.

RESULTS

Five of 12 patients were enrolled. The median age was 45 years (range, 24-55 years). A comparison of preoperative to postoperative status of SNSB, memory domain, especially delayed recall showed significant improvement. Although most of the domains showed improvement after surgery, the results were not statistically significant.

CONCLUSION

In our preliminary study, large proportions of adult patients with MMD demonstrate disruption of cognitive function. This suggests the possibility of chronic hypoperfusion as a primary cause of the neurocognitive impairment. When preoperative and postoperative status of cognitive function was compared, memory domain showed remarkable improvement. Although further study is needed, neurocognitive impairment may be an indication for earlier intervention with reperfusion procedures that can improve cognitive function.

Advances and surgical considerations in the treatment of moyamoya disease

Moyamoya is a rare disorder that involves steno-occlusive arterial changes of the anterior circulation, along with proliferative development of basal arterial collaterals. It is either idiopathic (called moyamoya disease) or the result of a specific underlying condition such as atherosclerosis, radiation therapy, or sickle cell disease (called moyamoya syndrome or phenomenon). In recent years, numerous insights into and advances in the understanding, evaluation, and management of moyamoya patients have occurred. This article briefly reviews the spectrum of moyamoya conditions and then provides a synopsis of numerous recent investigations that shed light on various aspects of the disease, including its clinical characteristics, natural history, underlying pathology, imaging, surgical techniques, and long-term patient outcome.

Selective neuropsychological impairments and related clinical factors in children with moyamoya disease of the transient ischemic attack type

PURPOSE

Moyamoya disease is characterized by progressive narrowing of bilateral internal carotid arteries. Neuropsychological impairments are suspected due to frequent involvement of the frontotemporal areas. The present study thus aimed to investigate the pattern of neuropsychological function in children diagnosed with moyamoya disease.

METHODS

Thirteen children with moyamoya disease of the transient ischemic attack type received standardized neuropsychological tests that evaluate general intellectual function, verbal comprehension, perceptual organization, working memory, processing speed, episodic memory, category fluency and visuospatial function. Related clinical factors were also analyzed.

RESULTS

The results showed single-domain cognitive impairment in around 15 % of patients and multiple-domain cognitive impairments in 23 % of patients. Selective impairments of episodic memory and processing speed were especially noted in those with younger age of onset and prolonged symptom duration.

CONCLUSIONS

Neuropsychological impairments are not infrequent in children with moyamoya disease despite normal general intellectual functioning. The pattern of cognitive dysfunction is often associated with lesions in frontotemporal areas. Early detection and intervention shall be considered regarding cognitive outcome in pediatric group.

Treatment of Moyamoya disease in the adult population with pial synangiosis

OBJECT

Surgical treatment of moyamoya disease in the adult population commonly uses direct revascularization, the superficial temporal artery (STA) to middle cerebral artery (MCA) bypass (STA-MCA). Pial synangiosis, a method of indirect revascularization, has been used in adult patients with moyamoya when STA-MCA bypass was not technically feasible. Although the effectiveness of pial synangiosis has been well described in children, only limited reports have examined its role in adult patients with moyamoya disease. In this study the authors report on their experience with pial synangiosis revascularization for this population.

METHODS

The authors reviewed the clinical and radiographic records of all adult patients (≥ 18 years of age) with moyamoya disease who underwent cerebral revascularization surgery using pial synangiosis at a single institution.

RESULTS

From 1985 to 2010, 66 procedures (6 unilateral, 30 bilateral) were performed on 36 adult patients with moyamoya disease. The mean age at surgery was 28.3 years, and 30 patients were female. Twenty-eight patients (77.8%) presented with transient ischemic attacks (TIAs), 24 (66.7%) with stroke, and 3 (8.3%) with hemorrhage. Preoperative Suzuki stage was III or higher in 50 hemispheres (75.8%) and 3 patients had undergone prior treatments to the affected hemisphere before pial synangiosis surgery. Clinical follow-up was available for an average of 5.8 years (range 0.6-14.1 years), with 26 patients (72.2%) followed for longer than 2 years. Postoperative angiography was available for 24 patients and 46 revascularized hemispheres, and 39 (84.8%) of the 46 hemispheres demonstrated good collateral formation (Matsushima Grade A or B). Postoperative complications included 3 strokes, 5 TIAs, and 2 seizures, and there was no hemorrhage during the follow-up period. One patient required additional revascularization surgery 8 months after pial synangiosis.

CONCLUSIONS

Pial synangiosis is a safe and durable method of cerebral revascularization in adult patients with moyamoya and can be considered as a potential treatment option for moyamoya disease in adults.

"Imaging Evaluation of Collaterals in the Brain: Physiology and Clinical Translation"

The cerebral collateral circulation is a network of blood vessels designed to preserve cerebral blood flow when primary routes fail. Though recognized for hundreds of years, the beneficial influence of collateral flow has now gained significant attention due to widely available, rapid, and real-time non-invasive imaging techniques. Multimodal CT and MRI based techniques, with angiographic and perfusion assessments, are becoming mainstays in the care of patients with ischemic brain disease. These methods allow for precise delineation of the structural and functional aspects of cerebral blood flow and as such provide valuable information that can inform the diagnosis and treatment of cerebral ischemia, in both the acute and chronic setting.

Functional imaging of cerebral perfusion

The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hemodynamic disorders in patients suffering from Alzheimer's disease or with arteriovenous malformations revealed by epilepsy. Functional MRI of the vasoreactivity also helps to better interpret the functional MRI activation in practice and in clinical research.

Moyamoya disease: a review of the literature

Moyamoya disease is a rare progressive cerebrovascular disorder that can be congenital or acquired and involves progressive stenosis and occlusion of cerebral arteries. The brain through compensatory angeogenesis then attempts to compensate for ischemia by producing a local network of tiny blood vessels, which appear cloud-like on angiograms. Consistent with multifocal or diffuse areas of ischemia, people with moyamoya often have multiple areas of cognitive impairment. A thorough literature review of the neuropsychological profile in individuals diagnosed with moyamoya disease is provided. Medical and neuropsychological/neurobehavioral data of a middle-aged woman with moyamoya disease is also described. The patient (MA) suffered an embolic shower with insult to both cerebral hemispheres. Neuropsychological results suggested a multifocal decline, with both cortical and subcortical involvement. Data were consistent with impairments in attention, concentration, executive skills, processing speed, and memory encoding and retrieval, with relatively spared aspects of memory and language skills. This case study supports the literature and provides an additional example of the neuropsychological profile and deficit pattern of an individual with moyamoya following an embolic stroke shower.