Intracranial hemodynamic changes during adult moyamoya disease progression

The effects of anastomoses between anterior and posterior circulation on postoperative prognosis of patients with moyamoya disease

BACKGROUND

Moyamoya disease (MMD) is a chronic ischemic cerebrovascular disease. Collateral circulation in MMD has emerged as a research focus. Our aims were to assess the impact of anastomoses between the anterior and posterior circulations on the prognosis of MMD patients.

METHODS

We reviewed the preoperative digital subtraction angiography images of patients with MMD who underwent revascularization surgery at our hospital between March 2014 and May 2020 and divided the patients into two groups: those with anastomoses (PtoA group) and those without anastomoses (non-PtoA group). The differences in follow-up (more than 6 months) collateral vessel establishment (Matsushima grade) and the modified Rankin Scale (mRS) were compared between the two groups as well as between the patients with different degrees of anastomoses. The early complications following revascularization were also compared between the two groups.

RESULTS

This study included 104 patients with MMD, of which 38 were non-PtoA and 66 were PtoA. There were no significant differences in Matsushima score (P = 0.252) and mRS score (P = 0.066) between the two groups. In addition, Matsushima score (P = 0.243) and mRS score (P = 0.360) did not differ significantly between patients with different degrees of anastomoses. However, the non-PtoA group had a significantly higher rate of cerebral hyperperfusion syndrome (CHS) than the PtoA group (34.2% vs 16.7%, P = 0.041).

CONCLUSION

MMD patients without anastomoses between anterior and posterior circulations preoperatively should be vigilant of the occurrence of CHS in the early stages after revascularization.

Prediction of cerebral infarction after bypass surgery in adult moyamoya disease: using pulsatility index on TCD

BACKGROUND

At present, the most effective treatment for symptomatic moyamoya disease (MMD) is surgery. However, the high incidence of postoperative complications is a serious problem plaguing the surgical treatment of MMD, especially the acute cerebral infarction. Decreased cerebrovascular reserve is an independent risk factor for ischemic infarction, and the pulsatility index (PI) of transcranial Doppler (TCD) is a common intuitive index for evaluating intracranial vascular compliance. However, the relationship between PI and the occurrence of ischemic stroke after operation is unclear.

OBJECTIVE

To explore whether the PI in the middle cerebral artery (MCA) could serve as a potential predictor for the occurrence of ischemic infarction after bypass surgery in MMD.

METHODS

We performed a retrospective analysis of data from 71 patients who underwent combined revascularization surgery, including superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis and encephalo-duro-myo-synangiosis (EDMS). The patients were divided into two groups according to the median of ipsilateral MCA-PI before operation, low PI group (MCA-PI < 0.614) and high PI group (MCA-PI ≥ 0.614). Univariate and multivariate regression analysis were used to explore risk factors affecting the occurrence of postoperative cerebral infarction.

RESULTS

Among the 71 patients with moyamoya disease, 11 patients had cerebral infarction within one week after revascularization. Among them, 10 patients' ipsilateral MCA-PI were less than 0.614, and another one's MCA- PI is higher than 0.614. Univariate analysis showed that the lower ipsilateral MCA-PI (0.448 ± 0.109 vs. 0.637 ± 0.124; P = 0.001) and higher Suzuki stage (P = 0.025) were linked to postoperative cerebral infarction. Multivariate analysis revealed that lower ipsilateral MCA-PI was an independent risk factor for predicting postoperative cerebral infarction (adjusted OR = 14.063; 95% CI = 6.265 ~ 37.308; P = 0.009).

CONCLUSIONS

A lower PI in the ipsilateral MCA may predict the cerebral infarction after combined revascularization surgery with high specificity. And combined revascularization appears to be safer for the moyamoya patients in early stages.

Mass cytometry revealed the circulating immune cell landscape across different Suzuki stages of Moyamoya disease

Moyamoya disease (MMD) is a cerebrovascular disorder marked by progressive arterial narrowing, categorized into six stages known as Suzuki stages based on angiographic features. Growing evidence indicates a pivotal role of systemic immune and inflammatory responses in the initiation and advancement of MMD. This study employs high-dimensional mass cytometry to reveal the immunophenotypic characteristics of peripheral blood immune cells (PBMCs) at various Suzuki stages, offering insights into the progression of MMD. PBMC samples from eight patients with early-stage MMD (Suzuki stages II and III) and eight patients with later-stage MMD (Suzuki stages IV, V, and VI) were analyzed using high-dimensional mass cytometry to evaluate the frequency and phenotype of immune cell subtypes. We identified 15 cell clusters and found that the immunological features of early-stage MMD and later-stage MMD are composed of cluster variations. In this study, we confirmed that, compared to later-stage MMD, the early-stage MMD group exhibits an increase in non-classical monocytes. As the Suzuki stage level increases, the proportions of plasmacytoid DCs and monocyte-derived DCs decrease. Furthermore, T cells, monocytes, DCs, and PMN-MDSCs in the early-stage MMD group show activation of the canonical NF-κB signaling pathway. We summarized and compared the similarities and differences between early-stage MMD patients and later-stage MMD patients. There is a potential role of circulating immune dysfunction and inflammatory responses in the onset and development of MMD.

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.

Neuromonitoring in Children with Cerebrovascular Disorders

BACKGROUND

Cerebrovascular disorders are an important cause of morbidity and mortality in children. The acute care of a child with an ischemic or hemorrhagic stroke or cerebral sinus venous thrombosis focuses on stabilizing the patient, determining the cause of the insult, and preventing secondary injury. Here, we review the use of both invasive and noninvasive neuromonitoring modalities in the care of pediatric patients with arterial ischemic stroke, nontraumatic intracranial hemorrhage, and cerebral sinus venous thrombosis.

METHODS

Narrative review of the literature on neuromonitoring in children with cerebrovascular disorders.

RESULTS

Neuroimaging, near-infrared spectroscopy, transcranial Doppler ultrasonography, continuous and quantitative electroencephalography, invasive intracranial pressure monitoring, and multimodal neuromonitoring may augment the acute care of children with cerebrovascular disorders. Neuromonitoring can play an essential role in the early identification of evolving injury in the aftermath of arterial ischemic stroke, intracranial hemorrhage, or sinus venous thrombosis, including recurrent infarction or infarct expansion, new or recurrent hemorrhage, vasospasm and delayed cerebral ischemia, status epilepticus, and intracranial hypertension, among others, and this, is turn, can facilitate real-time adjustments to treatment plans.

CONCLUSIONS

Our understanding of pediatric cerebrovascular disorders has increased dramatically over the past several years, in part due to advances in the neuromonitoring modalities that allow us to better understand these conditions. We are now poised, as a field, to take advantage of advances in neuromonitoring capabilities to determine how best to manage and treat acute cerebrovascular disorders in children.

The Pathogenetic Mechanism for Moyamoya Vasculopathy Including a Possible Trigger Effect of Increased Flow Velocity

Moyamoya disease (MMD), which commonly exhibits moyamoya vasculopathy characterized by chronic progressive steno-occlusive lesions in the circle of Willis with "moyamoya" collateral vessels, has been well known for its unique demographic and clinical features. Although the discovery of the susceptibility gene RNF213 for MMD revealed the factor for its predominance in East Asians, the mechanisms underlying other predominant conditions (females, children, young to middle-aged adults, and anterior circulation) and lesion formation are yet to be determined. As MMD and moyamoya syndrome (MMS), which secondarily produces moyamoya vasculopathy due to pre-existing diseases, have the same vascular lesions despite differences in their original pathogenesis, they may share a common trigger for the development of vascular lesions. Thus, we herein consider a common trigger from a novel perspective on blood flow dynamics. Increased flow velocity in the middle cerebral arteries is an established predictor of stroke in sickle cell disease, which is often complicated by MMS. Flow velocity is also increased in other diseases complicated by MMS (Down syndrome, Graves' disease, irradiation, and meningitis). In addition, increased flow velocity occurs under the predominant conditions of MMD (females, children, young to middle-aged adults, and anterior circulation), suggesting a relationship between flow velocity and susceptibility to moyamoya vasculopathy. Increased flow velocity has also been detected in the non-stenotic intracranial arteries of MMD patients. In a pathogenetic overview of chronic progressive steno-occlusive lesions, a novel perspective including the trigger effect of increased flow velocity may provide insights into the mechanisms underlying their predominant conditions and lesion formation.

Pediatric Moyamoya Biomarkers: Narrowing the Knowledge Gap

Moyamoya is a progressive cerebrovascular disorder that leads to stenosis of the arteries in the distal internal carotid, proximal middle cerebral and proximal anterior cerebral arteries of the circle of Willis. Typically a network of collaterals form to bypass the stenosis and maintain cerebral blood flow. As moyamoya progresses it affects the anterior circulation more commonly than posterior circulation, and cerebral blood flow becomes increasingly reliant on external carotid supply. Children with moyamoya are at increased risk for ischemic symptoms including stroke and transient ischemic attacks (TIA). In addition, cognitive decline may occur over time, even in the absence of clinical stroke. Standard of care for stroke prevention in children with symptomatic moyamoya is revascularization surgery. Treatment of children with asymptomatic moyamoya with revascularization surgery however remains more controversial. Therefore, biomarkers are needed to assist with not only diagnosis but also with determining ischemic risk and identifying best surgical candidates. In this review we will discuss the current knowledge as well as gaps in research in relation to pediatric moyamoya biomarkers including neurologic presentation, cognitive, neuroimaging, genetic and biologic biomarkers of disease severity and ischemic risk.

The Supratrochlear Artery Sign—A New Piece in the Puzzle of Cerebral Vasospasm

Background: Cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) has been extensively investigated, but the impact of collateralization remains unclear. We investigated the predictive value of collateral activation for delayed cerebral ischemia (DCI)-related infarctions and functional outcome. Methods: Data from 43 patients with CVS (January 2014 to August 2021) were evaluated for the angiographic presence of leptomeningeal and ophthalmic collaterals (anterior falcine artery (AFA), supratrochlear artery (STA), dorsal nasal artery (DNA)) on internal carotid artery angiograms. Vasospasm-related infarction and the modified Rankin Scale (mRS) score after six months were chosen as the endpoints. Results: 77% of the patients suffered from DCI-related infarctions. In 233 angiograms (at hospitalization, before spasmolysis, after six months), positive vessel signs were observed in 31 patients for STA, 35 for DNA, and 31 for AFA. The STA sign had the highest positive (84.6%) and negative (85.7%) predictive value for unfavorable outcome (mRS 4–6) in patients aged ≥50 years. DNA and AFA signs were not meaningful predictors for either endpoint. Leptomeningeal collaterals showed a positive Pearson’s correlation with the STA sign in 87.5% (p = 0.038) without providing any prediction for either endpoint. Conclusions: The STA sign is associated with clinical outcome in patients with CVS after SAH aged ≥50 years, and was correlated with the occurrence of leptomeningeal collaterals.

Clinical Features and Outcomes of Intracranial Aneurysm Associated with Moyamoya Disease

Background and Purpose

Moyamoya disease (MMD) is a rare form of intracranial stenoocclusive disease that can be associated with intracranial aneurysms. We evaluated the clinical features and outcomes of MMD-associated aneurysms while focusing on their locations.

Methods

Between January 1998 and December 2018 there were 1,302 adult and pediatric patients diagnosed as MMD at a single institution. These patients included 38 with 44 MMD-associated aneurysms. The MMD-associated aneurysms were classified into two groups based on their locations: major-artery aneurysms and non-major-artery aneurysms. The clinical and radiological data for patients with MMD-associated aneurysms were reviewed retrospectively.

Results

The 44 MMD-associated aneurysms comprised 28 in major arteries and 16 in nonmajor arteries. All of the major-artery aneurysms were initially unruptured lesions, and follow-up angiography showed that 23 (82.1%) had an improved or stable status and 5 (17.9%) had a worse status. The non-major-artery aneurysms comprised 10 ruptured and 6 unruptured lesions, and follow-up angiography showed that 11 (68.8%) had improved or were stable and 5 (31.2%) had worsened. At the latest follow-up, there were four cases of unfavorable outcome: two initial hemorrhagic insults, one treatment-related morbidity, and one repeated-hemorrhage case.

Conclusions

MMD-associated aneurysms occurred in 3.3% of the MMD cohort in this study, of which 63.6% were major-artery aneurysms and 36.4% were non-major-artery aneurysms. The major-artery group included 17.9% that became angiographically worse, while 31.2% were growing or hemorrhaging in the non-major-artery group.

Angiographic Analysis of Natural Anastomoses between the Posterior and Anterior Cerebral Arteries in Moyamoya Disease and Syndrome

BACKGROUND AND PURPOSE

Moyamoya disease is a chronic neurovascular steno-occlusive disease of the internal carotid artery and its main branches, associated with the development of compensatory vascular collaterals. Literature is lacking about the precise description of these compensatory vascular systems. Usually, the posterior circulation is less affected, and its vascular flow could compensate the hypoperfusion of the ICA territories. The aim of this study was to describe these natural connections between the posterior cerebral artery and the anterior cerebral artery necessary to compensate the lack of perfusion of the anterior cerebral artery territories in the Moyamoya population.

MATERIALS AND METHODS

All patients treated for Moyamoya disease from 2004 to 2018 in 4 neurosurgical centers with available cerebral digital subtraction angiography were included. Forty patients (80 hemispheres) with the diagnosis of Moyamoya disease were evaluated. The presence of anastomoses between the posterior cerebral artery and the anterior cerebral artery was found in 31 hemispheres (38.7%).

RESULTS

Among these 31 hemispheres presenting with posterior cerebral artery-anterior cerebral artery anastomoses, the most frequently encountered collaterals were branches from the posterior callosal artery (20%) and the posterior choroidal arteries (20%). Another possible connection found was pio-pial anastomosis between cortical branches of the posterior cerebral artery and the anterior cerebral artery (15%). We also proposed a 4-grade classification based on the competence of these anastomoses to supply retrogradely the territories of the anterior cerebral artery.

CONCLUSIONS

We found 3 different types of anastomoses between the anterior and posterior circulations, with different abilities to compensate the anterior circulation. Their development depends on the perfusion needs of the territories of the anterior cerebral artery and can provide the retrograde refilling of the anterior cerebral artery branches.

Collateral Circulation in Moyamoya Disease: A New Grading System

Background and Purpose- Predicting the risk of stroke and determining intervention indications are highly important for patients with Moyamoya disease (MMD). Here, we evaluated a novel MMD grading system based on collateral circulation and Suzuki stage to evaluate symptoms and predict prognosis. Methods- In total, 301 idiopathic MMD patients were retrospectively analyzed between 2014 and 2016. A collateral circulation grading system with scores ranging from 1 to 12 was established: the anatomic extent of pial collateral blood flow from posterior cerebral artery to middle cerebral artery and anterior cerebral artery was scored from 1 to 6; perforator collateral and internal cerebral artery flow were scored as 6 to 1, which corresponded to Suzuki stages 1 to 6. Dynamic susceptibility contrast-magnetic resonance imaging was used to evaluate hemodynamic status. We assessed the association between the grading system and clinical characteristics. Results- We analyzed 364 symptomatic hemispheres of 301 patients (146 males, 28±16 years). Ischemic patients who presented with infarction were more likely to score <8 points (P<0.001), whereas those with ischemia symptoms (transient ischemic attack and headache) were more likely to score >8 points. Hemorrhagic patients who presented with intraparenchymal hemorrhage were more likely to score <8 points, whereas those who presented with intraventricular hemorrhage were more likely to score >8 points (P<0.001). According to dynamic susceptibility contrast-magnetic resonance imaging, lower scores were correlated with more severe time to peak delay (P<0.001) and worse relative cerebral blood volume ratio (P=0.016) and cerebral flow ratio (P=0.002). Encephaloduroarteriosynangiosis was performed in 348 symptomatic hemispheres. Patients who had collateral scores <4 points were more likely to have a postoperative stroke and a worse prognosis during the follow-up. Conclusions- This new MMD collateral grading system correlated well with clinical symptoms, hemodynamic status, and therapeutic prognosis and may facilitate risk stratification and prognosis predictions in patients with MMD.

Revascularization Surgery in Patients with Ischemic-Type Moyamoya Disease: Predictors for Postoperative Stroke and Long-Term Outcomes

BACKGROUND

Recurrent stroke after surgical revascularization is still a big issue for moyamoya disease (MMD). This study aims to identify predictors for postoperative stroke and unfavorable outcome in ischemic-type MMD.

METHODS

We identified a consecutive series of patients with ischemic-type MMD who underwent revascularization between January 2005 and December 2012. Predictors for postoperative stroke and functional outcomes were assessed with logistic and Cox regression analysis.

RESULTS

A total of 346 patients underwent 437 revascularization procedures and the mean follow-up period was 4.0 years. The incidence of perioperative stroke was 6.9%. Being adult at onset (odds ratio [OR], 5.033; 95% confidence interval [CI], 1.447-17.506; P = 0.011) and posterior cerebral artery (PCA) stenosis (OR, 3.364; 95% CI, 1.588-7.265; P = 0.002) before surgery were predictors of perioperative stroke. The annual subsequent stroke rate beyond 30 days after surgery was 1.2%. Subsequent stroke events tended to occur throughout the first 5 years after surgery in adults, whereas in children they mainly occurred within the first 2 years after surgery. Age at onset (OR, 1.025; 95% CI, 1.003-1.048; P = 0.023), ischemic stroke or transient ischemic attack at presentation (OR, 2.703; 95% CI, 1.062-6.875; P = 0.037), and PCA involvement (OR, 2.664; 95% CI, 1.462-4.854; P = 0.001) were associated with higher risk of overall postoperative stroke. PCA involvement (OR, 2.62; 95% CI, 1.33-5.15; P = 0.005), internal carotid artery supraclinoid segment occlusion (OR, 2.76; 95% CI, 1.27-6.03; P = 0.011), and older age at onset (OR, 1.03; 95% CI, 1.01-1.05; P = 0.033) were predictive of unfavorable outcome.

CONCLUSIONS

Patients with ischemic-type MMD at an older age and more severe angiopathy might be at higher risk of recurrent stroke and unfavorable outcome after revascularization.

Anatomic and Angiographic Analyses of Ophthalmic Artery Collaterals in Moyamoya Disease

BACKGROUND AND PURPOSE

Moyamoya disease is a progressive neurovascular pathology defined by steno-occlusive disease of the distal internal carotid artery and associated with the development of compensatory vascular collaterals. The etiology and exact anatomy of vascular collaterals have not been extensively studied. The aim of this study was to describe the anatomy of collaterals developed between the ophthalmic artery and the anterior cerebral artery in a Moyamoya population.

MATERIALS AND METHODS

All patients treated for Moyamoya disease from 2004 to 2016 in 4 neurosurgical centers with available cerebral digital subtraction angiography were included. Sixty-three cases were evaluated, and only 38 met the inclusion criteria. Two patients had a unilateral cervical internal carotid occlusion that limited analysis of ophthalmic artery collaterals to one hemisphere. This study is consequently based on the analysis of 74 cerebral hemispheres.

RESULTS

Thirty-eight patients fulfilled the inclusion criteria. The most frequently encountered anastomosis between the ophthalmic artery and cerebral artery was a branch of the anterior ethmoidal artery (31.1%, 23 hemispheres). In case of proximal stenosis of the anterior cerebral artery, a collateral from the posterior ethmoidal artery could be visualized (16 hemispheres, 21.6%). One case (1.4%) of anastomosis between the lacrimal artery and the middle meningeal artery that permitted the vascularization of a middle cerebral artery territory was also noted.

CONCLUSIONS

Collaterals from the ophthalmic artery are frequent in Moyamoya disease. Their development depends on the perfusion needs of the anterior cerebral artery territories. Three other systems of compensation could be present (callosal circle, leptomeningeal anastomosis, and duro-pial anastomoses).

Hemodynamic contribution of transdural collateral flow in adult patients with moyamoya disease

To evaluate the hemodynamic contributions of collateral flow in adult patients with moyamoya disease, neurological deterioration or fluctuation during admission, Suzuki grade, various collateral routes, lesion volume, cerebral blood flow (CBF), and their associations were analyzed. Thirty patients (60 cerebral hemispheres, mean age 45 ± 25 years, and 73.3 % female) who were diagnosed with moyamoya disease or syndrome were enrolled over 3 years. Moyamoya stages from each hemisphere were stratified according to the Suzuki's criteria through six-vessel angiography into internal carotid arteries (ICAs), external carotid arteries (ECAs), and vertebral arteries (VAs). Collateral routes were categorized into the circle of Willis, leptomeningeal, and transdural. The volume of ipsilateral infarction was analyzed by magnetic resonance imaging. CBF volume was measured using color-coded duplex sonography. Suzuki's grade was inversely correlated with flow volume of the ICAs (p < 0.001), whereas no association was found with that of the ECAs (p = 0.445) or VAs (p = 0.096). Among hemispheres with ≥ grade 3 (n = 36), patients with transdural ECA collateral flow had less neurological deterioration or fluctuation (0.0 vs. 30.8 %, p = 0.047), smaller lesion volume (2.4 ± 3.6 vs. 27.6 ± 59.3 mL, p = 0.041), lower ICA flow (88.4 ± 45.9 vs. 146.2 ± 121.7 mL/min, p = 0.022), higher ECA flow (205.7 ± 77.7 vs. 135.9 ± 52.7 mL/min, p = 0.046), and a higher ECA/ICA flow volume ratio (31.8 ± 92.8 vs. 1.7 ± 1.9, p = 0.024). Our results suggest that ICA flow volume is inversely correlated with Suzuki grade, and that transdural ECA collaterals appear to be an important detour in adult patients with advanced stage moyamoya disease, suggesting a protector against an impending ischemic attack.

Low flow velocity in the middle cerebral artery predicting infarction after bypass surgery in adult moyamoya disease

OBJECTIVE Direct and indirect bypass surgeries are recognized as the most effective treatments for preventing further stroke in adults with moyamoya disease (MMD). However, the risk factors for postoperative infarction after bypass surgery for MMD are not well established. Therefore, the objective of this study was to investigate the risk factors for postoperative infarction. In particular, the authors sought to determine whether transcranial Doppler (TCD) ultrasonography measurements of mean flow velocity (MFV) in the middle cerebral artery (MCA) could predict postrevascularization infarction. METHODS The medical records of patients with MMD who underwent direct bypass surgery at the authors' institution between July 2012 and April 2015 were reviewed. The MFV in the MCA was measured with TCD ultrasonography and categorized as high (> 80 cm/sec), medium (40-80 cm/sec), and low (< 40 cm/sec). Postoperative MRI, including diffusion-weighted imaging, was performed for all patients within a week of their surgery. Angiographic findings were classified according to the Suzuki scale. Postrevascularization infarction was defined as any diffusion restriction on postoperative MRI scans. Postoperative neurological status was assessed through a clinical chart review, and the modified Rankin Scale was used to evaluate clinical outcomes. RESULTS Of 43 hemispheres in which bypass surgery for MMD was performed, 11 showed postrevascularization infarction. Ten of these hemispheres had low MFV and 1 had medium MFV in the ipsilateral MCA. In both univariate and multivariate analyses, a low MFV was associated with postrevascularization infarction (adjusted OR 109.2, 95% CI 1.9-6245.3). A low MFV was also statistically significantly associated with more advanced MMD stage (p = 0.02). CONCLUSIONS A low MFV in the ipsilateral MCA may predict postrevascularization infarction. Bypass surgery for MMD appears to be safe in early-stage MMD. Results of TCD ultrasonography provide clinical data on the hemodynamics in MMD patients before and after revascularization.

Transcranial Doppler Sonography in Pediatric Neurocritical Care: A Review of Clinical Applications and Case Illustrations in the Pediatric Intensive Care Unit

Transcranial Doppler sonography is a noninvasive, real-time physiologic monitor that can detect altered cerebral hemodynamics during catastrophic brain injury. Recent data suggest that transcranial Doppler sonography may provide important information about cerebrovascular hemodynamics in children with traumatic brain injury, intracranial hypertension, vasospasm, stroke, cerebrovascular disorders, central nervous system infections, and brain death. Information derived from transcranial Doppler sonography in these disorders may elucidate underlying pathophysiologic characteristics, predict outcomes, monitor responses to treatment, and prompt a change in management. We review emerging applications for transcranial Doppler sonography in the pediatric intensive care unit with case illustrations from our own experience.

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.