Perfusion characteristics of Moyamoya disease: an anatomically and clinically oriented analysis and comparison

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.

White and Gray Matter Perfusion in Children with Moyamoya Angiopathy after Revascularization Surgery

INTRODUCTION

Surgical revascularization is very effective in patients with moyamoya angiopathy (MMA) and leads to improvements in cortical perfusion parameters. However, changes in white matter hemodynamics are still underestimated. To date, only a few studies have examined brain perfusion changes within deep white matter after bypass surgery in patients with MMA.

METHODS

Ten children with MMA were evaluated using the CT perfusion technique before and after revascularization surgery. Brain perfusion parameters within gray and white matter were compared before and after surgery. The correlations between the perfusion parameters before surgery and the Suzuki stage, as well as between the perfusion parameters and the cognitive scores, were also evaluated.

RESULTS

Brain perfusion parameters improved significantly in both gray matter (predominantly due to cerebral blood flow within the anterior circulation, p < 0.01) and white matter (predominantly due to cerebral blood volume within the semiovale centrum, p < 0.001). We revealed that the pattern of improvement in perfusion in white matter differed from the pattern of improvement in perfusion in gray matter. Significant correlations were revealed between the Suzuki stage before surgery and the perfusion parameters within the posterior cerebral artery circulation (adjusted p < 0.05). There were also significant correlations between cognitive scores and brain perfusion parameters in gray matter and white matter (adjusted p < 0.05).

CONCLUSIONS

The perfusion parameters of gray matter and white matter in the brain improve differently after bypass surgery in patients with MMA. Different hemodynamics within these compartments could explain this.

T1w/T2w ratio is associated with the brush sign and perfusion delay in watershed regions in patients with moyamoya angiopathy

BACKGROUND

It has been shown recently using the T1w/T2w mapping technique that white matter microstructural integrity impairments exist in watershed regions patients with moyamoya angiopathy (MMA). We hypothesized that these changes could be associated with the prominence of other neuroimaging markers of chronic brain ischemia, such as perfusion delay and the brush sign.

METHODS

Thirteen adult patients with MMA (24 affected hemispheres) were evaluated using brain MRI and CT perfusion. The T1w/T2w signal intensity ratio, which reflects white matter integrity, was calculated in watershed regions (centrum semiovale and middle frontal gyrus). Brush sign prominence was evaluated with susceptibility-weighted MRI. Additionally, brain perfusion parameters such as cerebral blood flow (CBF), cerebral blood volume (CBF), and mean transit time (MTT) were assessed. Correlations between white matter integrity and perfusion changes in watershed regions, as well as the prominence of the brush sign, were evaluated.

RESULTS

Statistically significant negative correlations between the prominence of the brush sign and the T1w/T2w ratio values from the centrum semiovale and middle frontal white matter were found (R = -0.62 to 0.71, adjusted p < 0.05). Furthermore, there was a positive correlation between the T1w/T2w ratio values and the MTT values from the centrum semiovale (R = 0.65, adjusted p < 0.05).

CONCLUSIONS

We revealed that T1w/T2w ratio changes are associated with the prominence of the brush sign as well as white matter hypoperfusion in watershed regions in patients with MMA. This could be explained by chronic ischemia due to venous congestion in the deep medullary vein territory.

Physiological and pathophysiological mechanisms of the molecular and cellular biology of angiogenesis and inflammation in moyamoya angiopathy and related vascular diseases

Rationale

The etiology and pathophysiological mechanisms of moyamoya angiopathy (MMA) remain largely unknown. MMA is a progressive, occlusive cerebrovascular disorder characterized by recurrent ischemic and hemorrhagic strokes; with compensatory formation of an abnormal network of perforating blood vessels that creates a collateral circulation; and by aberrant angiogenesis at the base of the brain. Imbalance of angiogenic and vasculogenic mechanisms has been proposed as a potential cause of MMA. Moyamoya vessels suggest that aberrant angiogenic, arteriogenic, and vasculogenic processes may be involved in the pathophysiology of MMA. Circulating endothelial progenitor cells have been hypothesized to contribute to vascular remodeling in MMA. MMA is associated with increased expression of angiogenic factors and proinflammatory molecules. Systemic inflammation may be related to MMA pathogenesis.

Objective

This literature review describes the molecular mechanisms associated with cerebrovascular dysfunction, aberrant angiogenesis, and inflammation in MMA and related cerebrovascular diseases along with treatment strategies and future research perspectives.

Methods and results

References were identified through a systematic computerized search of the medical literature from January 1, 1983, through July 29, 2022, using the PubMed, EMBASE, BIOSIS Previews, CNKI, ISI web of science, and Medline databases and various combinations of the keywords "moyamoya," "angiogenesis," "anastomotic network," "molecular mechanism," "physiology," "pathophysiology," "pathogenesis," "biomarker," "genetics," "signaling pathway," "blood-brain barrier," "endothelial progenitor cells," "endothelial function," "inflammation," "intracranial hemorrhage," and "stroke." Relevant articles and supplemental basic science articles almost exclusively published in English were included. Review of the reference lists of relevant publications for additional sources resulted in 350 publications which met the study inclusion criteria. Detection of growth factors, chemokines, and cytokines in MMA patients suggests the hypothesis of aberrant angiogenesis being involved in MMA pathogenesis. It remains to be ascertained whether these findings are consequences of MMA or are etiological factors of MMA.

Conclusions

MMA is a heterogeneous disorder, comprising various genotypes and phenotypes, with a complex pathophysiology. Additional research may advance our understanding of the pathophysiology involved in aberrant angiogenesis, arterial stenosis, and the formation of moyamoya collaterals and anastomotic networks. Future research will benefit from researching molecular pathophysiologic mechanisms and the correlation of clinical and basic research results.

The sick(le) brain and spine: neuroimaging findings in paediatric patients with sickle cell disease

Sickle cell disease (SCD) is an autosomal recessive haemoglobinopathy, which manifests as multisystem ischaemia and infarction, as well as haemolytic anaemia. The morphological changes of red blood cells (RBCs) that promote ischaemia/infarction as the main multi-systemic manifestation, with associated vasculopathy, may also lead to haemorrhage and fat embolisation. Bone infarctions, whether of the skull or spine, are relatively common with subsequent increased infectious susceptibility. We present a broad spectrum of brain and spine imaging findings of SCD from a level III paediatric hospital in Lisbon, between 2010 and 2022. Our aim is to highlight brain and spine imaging findings from a serial review of multiple patients with SCD and respective neuroimaging characterisation.

18F-FDG PET and a classifier algorithm reveal a characteristic glucose metabolic pattern in adult patients with moyamoya disease and vascular cognitive impairment

Vascular cognitive impairment (VCI) is a critical issue in moyamoya disease (MMD). However, the glucose metabolic pattern in these patients is still unknown. This study aimed to identify the metabolic signature of cognitive impairment in patients with MMD using ¹⁸F-2-fluoro-2-deoxy-D-glucose positron emission tomography (¹⁸F-FDG PET) and establish a classifier to identify VCI in patients with MMD. One hundred fifty-two patients with MMD who underwent brain ¹⁸F-FDG PET scans before surgery were enrolled and classified into nonvascular cognitive impairment (non-VCI, n = 52) and vascular cognitive impairment (VCI, n = 100) groups according to neuropsychological test results. Additionally, thirty-three health controls (HCs) were also enrolled. Compared to HCs, patients in the VCI group exhibited extensive hypometabolism in the bilateral frontal and cingulate regions and hypermetabolism in the bilateral cerebellum, while patients in the non-VCI group showed hypermetabolism only in the cerebellum and slight hypometabolism in the frontal and temporal regions. In addition, we found that the patients in the VCI group showed hypometabolism mainly in the left basal ganglia compared to those in the non-VCI group. The sparse representation-based classifier algorithm taking the SUVr of 116 Anatomical Automatic Labeling (AAL) areas as features distinguished patients in the VCI and non-VCI groups with an accuracy of 82.4%. This study demonstrated a characteristic metabolic pattern that can distinguish patients with MMD without VCI from those with VCI, namely, hypometabolic lesions in the left hemisphere played a more important role in cognitive decline in patients with MMD.

Using arterial spin labeling to measure cerebrovascular reactivity in Moyamoya disease: Insights from simultaneous PET/MRI

Cerebrovascular reactivity (CVR) reflects the CBF change to meet different physiological demands. The reference CVR technique is PET imaging with vasodilators but is inaccessible to most patients. DSC can measure transit time to evaluate patients suspected of stroke, but the use of gadolinium may cause side-effects. Arterial spin labeling (ASL) is a non-invasive MRI technique for CBF measurements. Here, we investigate the effectiveness of ASL with single and multiple post labeling delays (PLD) to replace PET and DSC for CVR and transit time mapping in 26 Moyamoya patients. Images were collected using simultaneous PET/MRI with acetazolamide. CVR, CBF, arterial transit time (ATT), and time-to-maximum (Tmax) were measured in different flow territories. Results showed that CVR was lower in occluded regions than normal regions (by 68 ± 12%, 52 ± 5%, and 56 ± 9%, for PET, single- and multi-PLD PCASL, respectively, all p < 0.05). Multi-PLD PCASL correlated slightly higher with PET (CCC = 0.36 and 0.32 in affected and unaffected territories respectively). Vasodilation caused ATT to reduce by 4.5 ± 3.1% (p < 0.01) in occluded regions. ATT correlated significantly with Tmax (R² > 0.35, p < 0.01). Therefore, multi-PLD ASL is recommended for CVR studies due to its high agreement with the reference PET technique and the capability of measuring transit time.

Daily Remote Ischemic Conditioning Can Improve Cerebral Perfusion and Slow Arterial Progression of Adult Moyamoya Disease—A Randomized Controlled Study

Background and Purpose

Moyamoya disease (MMD) is a complicated cerebrovascular disease with recurrent ischemic or hemorrhagic events. This study aimed to prove the safety and efficacy of remote ischemic conditioning (RIC) on MMD.

Methods

In total, 34 patients with MMD participated in this pilot, prospective randomized controlled study for 1 year. 18 patients were allocated into the RIC group, and 16 patients accepted routine medical treatment only. RIC-related adverse events were recorded. The primary outcome was the improvement ratio of mean cerebral blood flow (mCBF) in middle cerebral artery territory measured by multidelay pseudocontinuous arterial spin labeling, and the secondary outcomes were the cumulative incidence of major adverse cerebrovascular events (MACEs), the prevalence of stenotic-occlusive progression, and periventricular anastomosis at 1-year follow-up.

Results

In total, 30 of the 34 patients with MMD completed the final follow-up (17 in the RIC group and 13 in the control group). No adverse events of RIC were observed. The mCBF improvement ratio of the RIC group was distinctively higher compared with the control group (mCBF−whole-brain: 0.16 ± 0.15 vs. −0.03 ± 0.13, p = 0.001). Stenotic-occlusive progression occurred in 11.8% hemispheres in the RIC group and 38.5% in the control group (p = 0.021). The incidence of MACE was 5.9% in the RIC group and 30.8% in the control group (hazard ratio with RIC, 0.174; 95% CI, 0.019–1.557; p = 0.118). No statistical difference was documented in the periventricular anastomosis between the two groups after treatment.

Conclusions

Remote ischemic conditioning has the potential to be a safe and effective adjunctive therapy for patients with MMD largely due to improving cerebral blood flow and slowing the arterial progression of the stenotic-occlusive lesions. These findings warrant future studies in larger trials.

Motor excitability in bilateral moyamoya vasculopathy and the impact of revascularization

OBJECTIVE

Motor cortical dysfunction has been shown to be reversible in patients with unilateral atherosclerotic disease after cerebral revascularization. Moyamoya vasculopathy (MMV) is a rare bilateral stenoocclusive cerebrovascular disease. The aim of this study was to analyze the corticospinal excitability and the role of bypass surgery in restoring cortical motor function in patients by using navigated transcranial magnetic stimulation (nTMS).

METHODS

Patients with bilateral MMV who met the criteria for cerebral revascularization were prospectively included. Corticospinal excitability, cortical representation area, and intracortical inhibition and facilitation were assessed by nTMS for a small hand muscle (first dorsal interosseous) before and after revascularization. The clinically and/or hemodynamically more severely affected hemisphere was operated first as the leading hemisphere. Intra- and interhemispheric differences were analyzed before and after direct or combined revascularization.

RESULTS

A total of 30 patients with bilateral MMV were examined by nTMS prior to and after revascularization surgery. The corticospinal excitability was higher in the leading hemisphere compared with the non-leading hemisphere prior to revascularization. This hyperexcitability was normalized after revascularization as demonstrated in the resting motor threshold ratio of the hemispheres (preoperative median 0.97 [IQR 0.89-1.08], postoperative median 1.02 [IQR 0.94-1.22]; relative effect = 0.61, p = 0.03). In paired-pulse paradigms, a tendency for a weaker inhibition of the leading hemisphere was observed compared with the non-leading hemisphere. Importantly, the paired paradigm also demonstrated approximation of excitability patterns between the two hemispheres after surgery.

CONCLUSIONS

The study results suggested that, in the case of a bilateral chronic ischemia, a compensation mechanism between both hemispheres seemed to exist that normalized after revascularization surgery. A potential role of nTMS in predicting the efficacy of revascularization must be further assessed.

Time to peak and full width at half maximum in MR perfusion: valuable indicators for monitoring moyamoya patients after revascularization

Moyamoya disease (MMD) is a chronic, steno-occlusive cerebrovascular disorder of unknown etiology. Surgical treatment is the only known effective method to restore blood flow to affected areas of the brain. However, there are lack of generally accepted noninvasive tools for therapeutic outcome monitoring. As dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) is the standard MR perfusion imaging technique in the clinical setting, we investigated a dataset of nineteen pediatric MMD patients with one preoperational and multiple periodic DSC MRI examinations for four to thirty-eight months after indirect revascularization. A rigid gamma variate model was used to derive two nondeconvolution-based perfusion parameters: time to peak (TTP) and full width at half maximum (FWHM) for monitoring transitional bolus delay and dispersion changes respectively. TTP and FWHM values were normalized to the cerebellum. Here, we report that 74% (14/19) of patients improve in both TTP and FWHM measurements, and whereof 57% (8/14) improve more noticeably on FWHM. TTP is in good agreement with Tmax in estimating bolus delay. Our study data also suggest bolus dispersion estimated by FWHM is an additional, informative indicator in pediatric MMD monitoring.

Recognition of Cognitive Impairment in Adult Moyamoya Disease: A Classifier Based on High-Order Resting-State Functional Connectivity Network

Objective: Vascular cognitive impairment (VCI) is a common complication in adult patients with moyamoya disease (MMD), and is reversible by surgical revascularization in its early stage of mild VCI. However, accurate diagnosis of mild VCI is difficult based on neuropsychological examination alone. This study proposed a method of dynamic resting-state functional connectivity (FC) network to recognize global cognitive impairment in MMD. Methods: For MMD, 36 patients with VCI and 43 patients with intact cognition (Non-VCI) were included, as well as 26 normal controls (NCs). Using resting-state fMRI, dynamic low-order FC networks were first constructed with multiple brain regions which were generated through a sliding window approach and correlated in temporal dimension. In order to obtain more information of network interactions along the time, high-order FC networks were established by calculating correlations among each pair of brain regions. Afterwards, a sparse representation-based classifier was constructed to recognize MMD (experiment 1) and its cognitive impairment (experiment 2) with features extracted from both low- and high-order FC networks. Finally, the ten-fold cross-validation strategy was proposed to train and validate the performance of the classifier. Results: The three groups did not differ significantly in demographic features (p > 0.05), while the VCI group exhibited the lowest MMSE scores (p = 0.001). The Non-VCI and NCs groups did not differ significantly in MMSE scores (p = 0.054). As for the classification between MMD and NCs, the area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity of the classifier reached 90.70, 88.57, 93.67, and 73.08%, respectively. While for the classification between VCI and Non-VCI, the AUC, accuracy, sensitivity, and specificity of the classifier reached 91.02, 84.81, 80.56, and 88.37%, respectively. Conclusion: This study not only develops a promising classifier to recognize VCI in adult MMD in its early stage, but also implies the significance of time-varying properties in dynamic FC networks.

Preoperative computed tomography perfusion in pediatric moyamoya disease: a single-institution experience

OBJECTIVE

Moyamoya disease is a progressive occlusive arteriopathy for which surgical revascularization is indicated. In this retrospective study, the authors investigated the use of preoperative CT perfusion with the aim of establishing pathological data references.

METHODS

The authors reviewed the medical records of children with moyamoya disease treated surgically at one institution between 2016 and 2019. Preoperative CT perfusion studies were used to quantify mean transit time (MTT), cerebral blood volume (CBV), cerebral blood flow (CBF), and time to peak (TTP) for the anterior, middle, and posterior cerebral artery vascular territories for each patient. CT perfusion parameter ratios (diseased/healthy hemispheres) and absolute differences were compared between diseased and normal vascular territories (defined by catheter angiography studies). Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values for CT perfusion parameters for severe angiographic moyamoya were calculated.

RESULTS

Nine children (89% female) had preoperative CT perfusion data; 5 of them had evidence of unilateral hemispheric disease and 4 had bilateral disease. The mean age at revascularization was 77 months (range 40-144 months). The etiology of disease was neurofibromatosis type 1 (3 patients), Down syndrome (2), primary moyamoya disease (2), cerebral proliferative angiopathy (1), and sickle cell disease (1). Five patients had undergone unilateral revascularization. Among these patients, pathological vascular territories demonstrated increased MTT in 66% of samples, increased TTP in 66%, decreased CBF in 47%, and increased CBV in 87%. Severe moyamoya (Suzuki stage ≥ 4) had diseased/healthy ratios ≥ 1 for MTT in 78% of cases, for TTP in 89%, for CBF in 67%, and for CBV in 89%. The MTT and TTP region of interest ratio ≥ 1 demonstrated 89% sensitivity, 67% specificity, 80% PPV, and 80% NPV for the prediction of severe angiographic moyamoya disease.

CONCLUSIONS

Pathological hemispheres in these children with moyamoya disease demonstrated increased MTT, TTP, and CBV and decreased CBF. The authors' results suggest that preoperative CT perfusion may, with high sensitivity, be useful in deciphering perfusion mismatch in brain tissue in children with moyamoya disease. More severe angiographic disease displays a more distinct correlation, allowing surgeons to recognize when to intervene in these patients.

Identifying Hypoperfusion in Moyamoya Disease With Arterial Spin Labeling and an [15O]-Water Positron Emission Tomography/Magnetic Resonance Imaging Normative Database

Background and Purpose- Noninvasive imaging of brain perfusion has the potential to elucidate pathophysiological mechanisms underlying Moyamoya disease and enable clinical imaging of cerebral blood flow (CBF) to select revascularization therapies for patients. We used hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) technology to characterize the distribution of hypoperfusion in Moyamoya disease and its relationship to vessel stenosis severity, through comparisons with a normative perfusion database of healthy controls. Methods- To image CBF, we acquired [¹⁵O]-water PET as a reference and simultaneously acquired arterial spin labeling (ASL) MRI scans in 20 Moyamoya patients and 15 age-matched, healthy controls on a PET/MRI scanner. The ASL MRI scans included a standard single-delay ASL scan with postlabel delay of 2.0 s and a multidelay scan with 5 postlabel delays (0.7-3.0s) to estimate and account for arterial transit time in CBF quantification. The percent volume of hypoperfusion in patients (determined as the fifth percentile of CBF values in the healthy control database) was the outcome measure in a logistic regression model that included stenosis grade and location. Results- Logistic regression showed that anterior ( P<0.0001) and middle cerebral artery territory regions ( P=0.003) in Moyamoya patients were susceptible to hypoperfusion, whereas posterior regions were not. Cortical regions supplied by arteries with stenosis on MR angiography showed more hypoperfusion than normal arteries ( P=0.001), but the extent of hypoperfusion was not different between mild-moderate versus severe stenosis. Multidelay ASL did not perform differently from [¹⁵O]-water PET in detecting perfusion abnormalities, but standard ASL overestimated the extent of hypoperfusion in patients ( P=0.003). Conclusions- This simultaneous PET/MRI study supports the use of multidelay ASL MRI in clinical evaluation of Moyamoya disease in settings where nuclear medicine imaging is not available and application of a normative perfusion database to automatically identify abnormal CBF in patients.

Hemodynamic stress distribution identified by SPECT reflects ischemic symptoms of Moyamoya disease patients

This study aimed to validate the hypothesis that the ratio of cerebral blood flow (CBF) at rest in the lenticular nucleus (LN) territory to that in the middle cerebral artery (MCA) territory is higher in symptomatic Moyamoya disease (MMD) patients than in asymptomatic MMD patients. This was a retrospective observational study of adult patients with documented MMD who underwent single-photon emission computed tomography (SPECT) and had been examined at the Department of Neurosurgery of Keio University Hospital during a 10-year period (2006-2016). The diagnosis was made on the basis of typical imaging findings. We classified unoperated MMD patients into three groups: class I, no evidence of stenosis or occlusion hemispheres and without symptoms in unilateral MMD patients; class II, hemispheres with stenosis or occlusion but without ischemic symptoms; and class III, hemispheres with evidence of stenosis or occlusion associated with ischemic symptoms. Hemodynamic stress distribution (hdSD) was defined as the ratio of CBF in one LN to the CBF in the peripheral MCA; this was obtained by SPECT at rest. We compared the values of CBF and hdSD among the groups. A total of 173 adult patients were diagnosed with MMD from January 1, 2006, to January 1, 2016. Among them, 85 MMD patients underwent SPECT studies. After excluding inappropriate cases, 144 hemispheres were included in our analysis. hdSD was significantly higher (p < 0.001) in hemispheres with ischemic symptoms (class III, mean hdSD = 1.1; 36 sides) than in those without symptoms (class II, mean hdSD = 1.03; 82 sides). However, CBF at rest in the MCA or LN was not significantly associated with ischemic symptoms. The optimal threshold for hdSD to have ischemic symptoms was 1.040 (area under the curve; 74% sensitivity 91.7% and specificity 54.9%). We used SPECT to investigate cerebral blood from MMD patients and found that high hdSD values were predictive of ischemic symptom development in these patients.

Microstructural damage pattern of vascular cognitive impairment: a comparison between moyamoya disease and cerebrovascular atherosclerotic disease

Moyamoya disease and cerebrovascular atherosclerotic disease are both chronic ischemic diseases with similar presentations of vascular cognitive impairment. The aim of the present study was to investigate the patterns of microstructural damage associated with vascular cognitive impairment in the two diseases. The study recruited 34 patients with moyamoya disease (age 43.9 ± 9.2 years; 20 men and 14 women, 27 patients with cerebrovascular atherosclerotic disease (age: 44.6 ± 7.6 years; 17 men and 10 women), and 31 normal controls (age 43.6 ± 7.3 years; 18 men and 13 women) from Huashan Hospital of Fudan University in China. Cognitive function was assessed using the Mini-Mental State Examination, long-term delayed recall of Auditory Verbal Learning Test, Trail Making Test Part B, and the Symbol Digit Modalities Test. Single-photon emission-computed tomography was used to examine cerebral perfusion. Voxel-based morphometry and tract-based spatial statistics were performed to identify regions of gray matter atrophy and white matter deterioration in patients and normal controls. The results demonstrated that the severity of cognitive impairment was similar between the two diseases in all tested domains. Patients with moyamoya disease and those with cerebrovascular atherosclerotic disease suffered from disturbed supratentorial hemodynamics. Gray matter atrophy in bilateral middle cingulate cortex and parts of the frontal gyrus was prominent in both diseases, but in general, was more severe and more diffuse in those with moyamoya disease. White matter deterioration was significant for both diseases in the genu and body of corpus callosum, in the anterior and superior corona radiation, and in the posterior thalamic radiation, but in moyamoya disease, it was more diffuse and more severe. Vascular cognitive impairment was associated with regional microstructural damage, with a potential link between, gray and white matter damage. Overall, these results provide insight into the pathophysiological nature of vascular cognitive impairment. This study was approved by the Institutional Review Board in Huashan Hospital, China (approval No. 2014-278). This study was registered with ClinicalTrials.gov on December 2, 2014 with the identifier NCT02305407.

Gelatinolytic activity of autocrine matrix metalloproteinase-9 leads to endothelial de-arrangement in Moyamoya disease

Moyamoya disease (MMD) is a rare steno-occlusive cerebrovascular disorder. Mechanisms driving the formation of aberrant MMD vessels remain elusive. We collected serum and vessel specimens from MMD and atherosclerotic cerebrovascular disease (ACVD) patients serving as controls due to the same hypoxic stimulus but substantial differences in terms of vascular features. Based on patient material and an in vitro model mimicking ACVD and MMD conditions, matrix metalloproteinase-9 (MMP-9) and vascular-endothelial growth factor (VEGF) were tested for their potential involvement in cerebrovascular disintegration. While serum concentration of both molecules did not significantly differ in both patient groups, excessive collagenase activity and lowered collagen IV protein amount in MMD vessels pointed to a focal MMP-9 activity at the affected vessel sites. We observed overexpressed and autocrinely secreted MMP-9 and VEGF along with disturbances of EC-matrix interactions in MMD but not ACVD serum-treated cEND cells. These seemingly brain-specific effects were partially attenuated by VEGF signaling inhibition suggesting its role in the MMD etiology. In conclusion, our findings support the understanding of the high incidence of hemorrhagic and ischemic events in MMD and provide the basis for novel therapeutic strategies stopping or slowing the development of fragile cerebrovasculature or micro-bleeds characterizing the disease.

Hemodynamic mechanisms underlying elevated oxygen extraction fraction (OEF) in moyamoya and sickle cell anemia patients

Moyamoya is a bilateral, complex cerebrovascular condition characterized by progressive non-atherosclerotic intracranial stenosis and collateral vessel formation. Moyamoya treatment focuses on restoring cerebral blood flow (CBF) through surgical revascularization, however stratifying patients for revascularization requires abilities to quantify how well parenchyma is compensating for arterial steno-occlusion. Globally elevated oxygen extraction fraction (OEF) secondary to CBF reduction may serve as a biomarker for tissue health in moyamoya patients, as suggested in patients with sickle cell anemia (SCA) and reduced oxygen carrying capacity. Here, OEF was measured (TRUST-MRI) to test the hypothesis that OEF is globally elevated in patients with moyamoya (n = 18) and SCA (n = 18) relative to age-matched controls (n = 43). Mechanisms underlying the hypothesized OEF increases were evaluated by performing sequential CBF-weighted, cerebrovascular reactivity (CVR)-weighted, and structural MRI. Patients were stratified by treatment and non-parametric tests applied to compare study variables (significance: two-sided P < 0.05). OEF was significantly elevated in moyamoya participants (interquartile range = 0.38-0.45) compared to controls (interquartile range = 0.29-0.38), similar to participants with SCA (interquartile range = 0.37-0.45). CBF was inversely correlated with OEF in moyamoya participants. Elevated OEF was only weakly related to reductions in CVR, consistent with basal CBF level, rather than vascular reserve capacity, being most closely associated with OEF.

Improving Indirect Revascularization for Effective Treatment of Adult Moyamoya Disease: A Prospective Clinical, Cerebral Angiographic, and Perfusion Study

BACKGROUND

Indirect revascularization is simple and safe, but it is not commonly used in adult moyamoya disease owing to its unreliable effect. This prospective study aimed to evaluate the effectiveness of indirect revascularization in treating adult moyamoya disease after refinement of the surgical technique and perioperative care.

METHODS

Adult patients who underwent indirect revascularization as the primary treatment for moyamoya disease between November 2013 and January 2017 were studied. The indirect revascularization procedures included encephalo-duro-arterio-synangiosis and encephalo-myo-synangiosis in the temporal region and encephalo-pericranio-synangiosis in other hypoperfusion areas. The preoperative and postoperative clinical conditions, cerebral angiography findings, and time-to-peak prolongation areas on magnetic resonance perfusion studies were assessed to evaluate the revascularization effect. Refinements of the surgical technique included the selection of surgical area based on perfusion imaging, craniotomy size, and number of affected hemispheres, along with the inclusion of a dural flap in every procedure.

RESULTS

Nineteen patients (17 females and 2 males), and a total of 31 cerebral hemispheres, were included. The mean patient age was 32.7 ± 11.4 years. After a mean follow-up of 38.6 ± 11.5 months, all patients showed clinical improvement or stabilization. Available postoperative angiography demonstrated Matsushima grade A or B in 19 of 21 hemispheres. The mean time-to-peak prolongation index of all 31 hemispheres improved from 24.09 ± 9.83% preoperatively to 12.82 ± 6.75% at 3-6 months after surgery (P < 0.001). The complication rate was 12.9%, and all complications were transient.

CONCLUSIONS

With refinements of surgical techniques and perioperative care, indirect revascularization is more reliable and can be a viable alternative treatment for adult moyamoya disease. In our cohort, outcomes were satisfactory, with mean 38.6-month follow-up.

Association Between Champagne Bottle Neck Sign of Internal Carotid Artery and Ipsilateral Hemorrhagic Stroke in Patients with Moyamoya Disease

OBJECTIVE

To assess association between champagne bottle neck sign (CBNS) in carotid artery and intracranial hemorrhage in patients with moyamoya disease (MMD).

METHODS

This retrospective study included 76 consecutive patients with MMD without definite risk factors associated with intracranial hemorrhage who underwent preoperative angiography from January 2016 to December 2017. CBNS was defined as luminal diameter ratio of internal carotid artery/common carotid artery ≤0.5 on angiography. The right and left cerebral hemisphere in each patient was separately identified as hemorrhagic and nonhemorrhagic. Association between CBNS and intracranial hemorrhage was analyzed.

RESULTS

Of 76 patients with MMD, intracranial hemorrhage was found in 44 of 152 (28.9%) hemispheres, and 6.8% (3/44) had multiple events. Comparing carotid arteries without intracranial hemorrhage in ipsilateral hemispheres, patients with intracranial hemorrhage in the ipsilateral hemisphere had significantly smaller luminal diameter ratio of internal carotid artery/common carotid artery (0.49 ± 0.11 vs. 0.55 ± 0.12, P < 0.01) and higher prevalence of CBNS (63.7% vs. 41.7%, P = 0.01). Comparing hemispheres with intracranial hemorrhage, patients with ipsilateral carotid artery CBNS had significantly higher prevalence of hemorrhage in posterior territories than patients without CBNS (57.1% vs. 23.1%, P = 0.05). Logistic regression revealed that CBNS was significantly associated with ipsilateral intracranial hemorrhage before (odds ratio = 2.45; 95% confidence interval, 1.19-5.05; P = 0.02) and after (odds ratio = 3.43; 95% confidence interval, 1.50-7.87; P < 0.01) adjusting for female sex, lenticulostriate anastomosis, and choroidal anastomosis.

CONCLUSIONS

CBNS is significantly associated with intracranial hemorrhage in the ipsilateral hemisphere in patients with MMD, particularly intracranial hemorrhage in posterior territories.

Noninvasive Assessment of Hemodynamic Stress Distribution after Indirect Revascularization for Pediatric Moyamoya Vasculopathy

BACKGROUND AND PURPOSE

Indirect revascularization surgery is an effective treatment in children with Moyamoya vasculopathy. In the present study, we hypothesized that DSC-PWI may reliably assess the evolution of CBF-related parameters after revascularization surgery, monitoring the outcome of surgical pediatric patients with Moyamoya vasculopathy. Thus, we aimed to evaluate differences in DSC-PWI parameters, including the hemodynamic stress distribution, in surgical and nonsurgical children with Moyamoya vasculopathy and to correlate them with long-term postoperative outcome.

MATERIALS AND METHODS

Pre- and postoperative DSC parameters of 28 patients (16 females; mean age, 5.5 ± 4.8 years) treated with indirect revascularization were compared with those obtained at 2 time points in 10 nonsurgical patients (6 females; mean age, 6.9 ± 4.7 years). We calculated 4 normalized CBF-related parameters and their percentage variance: mean normalized CBF of the MCA territory, mean normalized CBF of the proximal MCA territory, mean normalized CBF of cortical the MCA territory, and hemodynamic stress distribution. The relationship between perfusion parameters and postoperative outcomes (poor, fair, good, excellent) was explored using 1-way analysis of covariance (P < .05).

RESULTS

A significant decrease of the mean normalized CBF of the proximal MCA territory and hemodynamic stress distribution and an increase of the mean normalized CBF of the cortical MCA territory were observed after revascularization surgery (P < .001). No variations were observed in nonsurgical children. Postoperative hemodynamic stress distribution and its percentage change were significantly different in outcome groups (P < .001).

CONCLUSIONS

DSC-PWI indices show postoperative hemodynamic changes that correlate with clinical outcome after revascularization surgery in children with Moyamoya disease.

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.

Lacunar infarction in adult patients with moyamoya disease

OBJECTIVES

Lacunar infarctions in moyamoya disease have rarely been described. We aimed to evaluate the features and prognosis of adult moyamoya patients with lacunar infarction.

PATIENTS AND METHODS

We reviewed 696 consecutive moyamoya patients admitted to our hospital from 2009 to 2015 to identify patients with lacunar infarctions. We compared the clinical features and prognosis of adult moyamoya patients with lacunar infarction and those with non-lacunar infarction. Follow-up was conducted by face-to-face reviews or by a structured telephone interview. Outcome measures were recurrent stroke events and functional outcomes by modified Rankin Scale (mRS).

RESULTS

We identified 32 patients with lacunar infarction among 197 adult moyamoya disease patients with infarctions. Patients with lacunar infarctions demonstrated similar angiographic features with patients with non-lacunar infarctions. During a mean follow-up of 33.02±20.49months, we observed recurrent stroke events in 1 patients with lacunar infarction and 14 patients with non-lacunar infarction. The mean follow-up mRS was significantly better in the lacunar group than in the non-lacunar group (0.59±0.56 vs. 1.13±1.24; P<0.001).

CONCLUSION

We identified that the moyamoya patients with lacunar infarctions had better functional outcomes comparing with patients with non-lacunar infarction after revascularization.

Grading of moyamoya disease allows stratification for postoperative ischemia in bilateral revascularization surgery

BACKGROUND

Moyamoya disease (MMD) may be graded based on DSA, the presence of ischemia in MRI and cerebrovascular reserve capacity allowing the prediction of ischemic symptoms in patients. Cerebral ischemia represents a severe complication in revascularization surgery. Focusing on different clinical features of hemodynamic impairment, MMD grading may allow prediction of ischemic complications. It was the aim to analyze whether MMD grading stratifies for ischemic complications in revascularization surgery for MMD.

METHOD

In 37 MMD patients a bilateral, standardized, one-staged revascularization approach consisting of STA-MCA bypass/encephalomyosynangiosis (EMS) and single EMS on the contralateral hemisphere was performed. Clinical data including DSA, MRI and rCBF (Xenon-CT) studies were assessed and used for grading MMD. All patients were observed on the ICU for at least 24 h and received CT imaging on the first postoperative day and in case of neurological deterioration. Ischemic complications were analyzed until the day of discharge and at 6-month follow-up.

RESULTS

Grading of MMD revealed 11 hemispheres (15 %) as grade I, 33 hemispheres (44 %) as grade II and 30 hemispheres (41 %) as grade III. Eight ischemic complications were observed (11 %). MMD grading demonstrated a significant correlation with ischemic complications: 0 complications in grade I, 3 in grade II (9 %) and 5 in grade III hemispheres (16 %; p < 0.05, Fisher's exact test).

CONCLUSIONS

The proposed grading system allows to stratify for ischemic complications in MMD patients that receive bilateral, one-staged revascularization surgery. Future studies will have to investigate its use for predicting ischemic complications in other revascularization strategies for MMD.

Hemodynamic stress distribution reflects ischemic clinical symptoms of patients with moyamoya disease

OBJECTIVE

Currently, the probability of diagnosing asymptomatic moyamoya disease is increasing. In this study, we consider a less invasive method for predicting future ischemic symptoms in patients with moyamoya disease.

METHODS

We reviewed cerebral blood flow (CBF)-related data obtained by xenon CT imaging (XeCT) in six patients with ischemic-type or asymptomatic moyamoya disease. The data were obtained as volume data using a 320-row CT, and applied to the automated region-of-interest-determining software (3DSRT) and converted to standardized images. Eight CBF-related parameters, including CBF value, cerebrovascular reserve capacity (CVRC), and hemodynamic distribution (hdSD), were compared between asymptomatic hemispheres and ischemic symptomatic hemispheres. A significant difference was determined by a two-sample t test. A difference with p<0.05 was considered significant. When statistically significant differences between parameters of asymptomatic hemispheres and ischemic symptomatic hemispheres were identified, cut-off points were calculated with receiver operating characteristic (ROC) curves. Change in the parameters before and after bypass surgery was also assessed.

RESULTS

Of the eight CBF-related parameters evaluated, statistically significant differences between the asymptomatic hemispheres and ischemic hemispheres were observed in the CBF value of the MCA region (CBF-MCA), both at rest and after acetazolamide loading, and in the hdSD, also both at rest and after acetazolamide loading. Of the four statistically significant parameters, ROC analysis revealed that the hdSD at rest and CBF-MCA after acetazolamide loading were the most sensitive and specific parameters (threshold 1.2, sensitivity 1, specificity 1 for hdSD at rest, and threshold 26.44mL/100g/min, sensitivity 1, specificity 1 for CBF-MCA after acetazolamide loading). From the CBF data obtained both before and after surgery from the three patients who had undergone direct bypass surgeries, the hdSD was higher than the threshold of 1.2 before surgery but decreased to lower than the threshold of 1.2 after surgery. Ischemic symptoms also resolved after surgery.

CONCLUSIONS

The data showed that hdSD at rest and CBF-MCA after acetazolamide loading reflects ischemic symptoms of patients with moyamoya disease. Thus, these parameters could be used as ischemic symptom markers for following patients with moyamoya disease. hdSD at rest is important because it is less invasive and can be performed without acetazolamide loading.

Comparison of cerebral blood flow data obtained by computed tomography (CT) perfusion with that obtained by xenon CT using 320-row CT

Cerebral blood flow (CBF) data obtained by computed tomography perfusion (CTP) imaging have been shown to be qualitative data rather than quantitative, in contrast with data obtained by other imaging methods, such as xenon CT (XeCT) imaging. Thus, interpatient comparisons of CBF values themselves obtained by CTP may be inaccurate. In this study, we have compared CBF ratios as well as CBF values obtained from CTP-CBF data to those obtained from XeCT-CBF data for the same patients to determine CTP-CBF parameters that can be used for interpatient comparisons. The data used in the present study were obtained as volume data using 320-row CT. The volume data were applied to an automated region of interest-determining software (3DSRT, version 3.5.2 ) and converted to 59 slices of 2 mm interval standardized images. In the present study, we reviewed 10 patients with occlusive cerebrovascular diseases (CVDs) undergoing both CTP and XeCT in the same period. Our study shows that ratios of CBF measurements, such as hemodynamic stress distribution (perforator-to-cortical flow ratio of middle cerebral artery [MCA] region) or the left/right ratio for the region of the MCA, calculated using CTP data have been shown to correlate well with the same ratios calculated using XeCT data. These results suggest that such CBF ratios could be useful for generating interpatient comparisons of CTP-CBF data obtained by 320-row CT among patients with occlusive CVD.

Collateralization and ischemia in hemodynamic cerebrovascular insufficiency

BACKGROUND

Moyamoya disease and atherosclerotic cerebrovascular occlusive disease lead to hemodynamic impairment of cerebral blood flow. One major differentiation between both disease entities lies in the collateralization pathways. The clinical implications of the collateralization pathways for the development of hemodynamic ischemia remain unknown. The aim was to characterize collateralization and ischemia patterns in patients with chronic hemodynamic compromise.

METHODS

Hemodynamic compromise was verified using acetazolamide-stimulated xenon-CT or SPECT in 54 patients [30 moyamoya and 24 atherosclerotic cerebrovascular disease (ACVD)]. All patients received MRI to differentiate hemodynamic ischemia into anterior/posterior cortical border zone infarction (CBI), inferior border zone infarction (IBI) or territorial infarction (TI). Digital subtraction angiography was applied to evaluate collateralization. Collateralization was compared and correlated with the localization of ischemia and number of vascular territories with impaired cerebrovascular reserve capacity (CVRC).

RESULTS

MM patients showed collateralization significantly more often via pericallosal anastomosis and the posterior communicating artery (flow in the anterior-posterior direction; MM: 95%/95% vs. ACVD: 23%/12%, p < 0.05). ACVD patients demonstrated collateralization via the anterior and posterior communicating arteries (flow in the posterior-anterior direction, MM: 6%/5% vs. ACVD: 62%/88%, p < 0.05). Patterns of infarction were comparable (aCBI: MM: 36% vs. ACVD: 35%; pCBI: MM: 10% vs. ACVD: 20%; IBI: MM: 35% vs. ACVD: 41%; TI: MM: 13% vs. ACVD: 18%). The number and localization of vascular territories with impaired CVRC were comparable.

CONCLUSIONS

Despite significant differences in collateralization, the infarct patterns and severity of CVRC impairment do not differ between MMV and ACVD patients. Cerebral collateralization does not allow reaching conclusions about the localization of cerebral ischemia or severity of impaired CVRC in chronic hemodynamic impairment.