Delayed posterior circulation insufficiency in pediatric moyamoya disease

Clinical Course, Therapy, and Long-Term Outcomes of Children With Moyamoya Disease and Posterior Cerebral Artery Involvement

BACKGROUND AND OBJECTIVES

Posterior cerebral artery involvement (PCAi) has been identified as an important factor related to poor prognosis in moyamoya disease (MMD). This study summarized the characteristics of children with MMD and PCAi, clarified the clinical course, identified prognostic predictors, and investigated the long-term effect of encephaloduroarteriosynangiosis for posterior circulation (EDAS-p).

METHODS

We retrospectively reviewed all our pediatric MMD cases with follow-up angiograms from November 2003 to December 2016. PCAi was classified as early-onset at initial diagnosis and delayed-onset after anterior circulation revascularization. Multivariable data including clinical features, radiographic findings, and surgical outcomes were analyzed.

RESULTS

Among 570 children with MMD, 246 (43.2%) had PCAi, with 176 (30.9%) classified as early-onset PCAi. During a median follow-up period of 10 years, 17.8% (70/394) of patients without initial PCAi developed delayed-onset PCAi. The median time to detection of a new PCA lesion was 15.5 (range 7-110) months from initial diagnosis, with a median age of 10.5 (3-22). Younger age at onset, familial occurrence, advanced Suzuki stages, and preoperative infarctions were predictors of delayed-onset PCAi. EDAS-p was performed on 294 hemispheres of 195 patients with PCAi. Stroke-free survival was significantly higher in the EDAS-p group than in the non-EDAS-p group (99.0% vs 90.2%; p < 0.001 [Breslow test]; p = 0.001 [log-rank test]; median follow-up: 101 months).

DISCUSSION

PCAi is not uncommon in children with MMD, underscoring the need for long-term close clinical monitoring, especially in patients with high-risk factors for PCA progression. EDAS-p may be a safe and effective procedure for preventing subsequent stroke in children with MMD and PCAi.

Surgical revascularization as a procedure to prevent neurological complications in children with moyamoya syndrome associated with neurofibromatosis I: a single institution case series

BACKGROUND

The optimal timing and surgical approach for surgical revascularization in patients with moyamoya syndrome (MMS) associated with neurofibromatosis type I (NF1) remain so far elusive. We aimed to compare the long-term clinical, radiological, and cognitive effects of different revascularization procedures in a pediatric cohort of NF1-associated MMS.

METHODS

We reviewed the clinical, radiological, and surgical data of 26 patients with NF1-associated MMS diagnosed at our institution between 2012 and 2022, at the clinical onset and last follow-up.

RESULTS

Indirect bypasses were performed in 12/26 patients (57.1%), while combined direct and indirect procedures in 9/26 subjects (42.9%); 5 patients did not undergo surgery. Through logistic regression analysis, pathological Wechsler Intelligence Scale for Children (WISC) at onset was found to be associated with symptom improvement at 1-year follow up (p = 0.006). No significant differences were found in long-term neurocognitive outcome and stroke rate in patients receiving combined or indirect bypass (p > 0.05).

CONCLUSIONS

Currently, whether combined or indirect bypass should be considered the treatment of choice in pediatric patients with NF1-associated MMS remains unclear, as well as the optimal time approach. In our series, no significant differences were found in long-term neurocognitive outcome and stroke rate between patients treated with either of these two approaches. Clinical evidence supports the crucial role of early diagnosis and surgical revascularization in subjects with MMS-associated NF1, even in case of mildly symptomatic vasculopathy. This allows to achieve a good long-term outcome with improved intellectual function and prevention of stroke and seizure in these patients.

Incidence and Outcomes of Posterior Circulation Involvement in Moyamoya Disease

BACKGROUND

Moyamoya disease (MMD) is a progressive, occlusive disease of the internal carotid arteries and their proximal branches, with the subsequent development of an abnormal vascular network that is rupture-prone. Steno-occlusive changes in the posterior cerebral arteries (PCAs) may contribute to worsened outcomes in patients with MMD; however, there is little information on the incidence and natural history of posterior circulation MMD (PCMMD). We describe clinical PCMMD characteristics in a large cohort of patients with MMD.

METHODS

We retrospectively reviewed patients with MMD treated between 1991 and 2019 at a large academic medical center. Demographics, perioperative outcomes, and radiological phenotypes were recorded for 770 patients. PCA disease was graded as either 0 (no disease), 1 (mild), 2 (moderate), or 3 (severe or occluded) based on cerebral angiography. Patients with angiographically confirmed MMD diagnosis with at least 6 months follow-up and completion of revascularization surgery were included; patients with intracranial atherosclerosis, intracranial dissection, vasculitis, and undefined inflammatory processes were excluded. The presence of stenosis/occlusion was graded radiographically to assess for disease progression and the prevalence of risk factors related to reduced progression-free survival.

RESULTS

In all, 686 patients met the inclusion criteria, with PCA disease identified in 282 (41.1%) patients. Of those 282 patients with PCMMD, disease severity ranged from 99 (35.1%) with mild, 72 (25.5%) with moderate, and 111 (39.4%) with severe. The total number of postoperative complications was significantly associated with PCMMD severity (P=0.0067). Additionally, PCMMD severity correlated with worse postoperative modified Rankin Scale scores (P<0.0001). At a mean follow-up of 6.0±3.9 (range, 0.1-25.0) years, a total of 60 (12.6%) patients showed new/worsening PCMMD. The overall postoperative, progression-free survival in patients with PCMMD was 95.4% at 1 year, 82.4% at 3 years, 68.8% at 5 years, and 28.3% at 10 years, with prognostic factors for progression including preoperative PCMMD status, history of tobacco use, and hypertension (P<0.0001, P<0.001, and P<0.0001, respectively).

CONCLUSIONS

PCA disease involvement in MMD is associated with higher rates of ischemic perioperative complications and worsened functional outcomes, likely due to reduced collateral flow. Ten-year progression of PCA disease is highly likely and should be monitored throughout follow-up; future studies will assess the impact of PCA disease progression on long-term outcomes.

Posterior cerebral territory ischemia in pediatric moyamoya: Surgical techniques and long-term clinical and radiographic outcomes

PURPOSE

To describe a surgical technique for posterior cerebral revascularization in pediatric patients with moyamoya arteriopathy. Here, we describe the clinical characteristics, surgical indications, operative techniques, and clinical and radiographic outcomes in a series of pediatric patients with moyamoya disease affecting the posterior cerebral artery (PCA) territory.

METHODS

A retrospective single-center series of all pediatric patients with moyamoya disease who presented to our institute between July 2009 through August 2019 were reviewed. The clinical characteristics, surgical indications, operative techniques, and long-term clinical and radiographic outcomes of pediatric moyamoya patients with PCA territory ischemia were collected and analyzed.

RESULTS

A total of 10 PCA revascularization procedures were performed in 9 patients, 5 female, ages 1 to 11.1 years (average 5.2 years). Complications included 1 stroke, with no infections, hemorrhages, seizures, or deaths. One patient had less than 1 year of radiographic and clinical follow-up. In 8 of 9 patients with at least 1 year of radiographic follow-up, there was engraftment of surgical vessels present in all cases. No new strokes were identified on long-term follow-up despite the radiographic progression of the disease. In the 8 cases available for analysis, the average follow-up was 50.8 months with a range of 12 to 117 months.

CONCLUSIONS

PCA territory ischemia in patients with progressive moyamoya disease can be surgically treated with indirect revascularization. Here, we describe our experience with PCA revascularization procedures for moyamoya disease, including pial pericranial dural (PiPeD) revascularization and pial synangiosis utilizing the occipital artery. These surgical options may be useful for decreasing the risk of stroke in pediatric moyamoya patients with severe posterior circulation disease.

Technical evolution of pediatric neurosurgery: moyamoya disease

Moyamoya disease (MMD) is a rare steno-occlusive disease of the bilateral internal carotid arteries that predominantly occurs in East Asia. Since the first description of the MMD by Suzuki and Takaku in 1969, significant advances have been made in both basic and clinical understanding of the disease. The incidence and prevalence of pediatric MMD have increased, potentially due to improved detection rates. The advancement of neuroimaging techniques has enabled MRI-based diagnostics and detailed visualization of the vessel wall. Various methods of surgical treatments are successful in pediatric MMD patients, and recent studies emphasize the importance of reducing postoperative complications since the goal of MMD surgery is to prevent future cerebral infarction and hemorrhage. Long-term outcomes following appropriate surgical treatment in pediatric MMD patients have shown promising results, including favorable outcomes in very young patients. Further studies with a large patient cohort are needed to establish individualized risk group stratification for determining the optimal timing of surgical treatment and to conduct multidisciplinary outcome assessments.

Comparison of Bifrontal Craniotomy and Multiple Burr Hole Encephalogaleoperiosteal-Synangiosis for Pediatric Moyamoya Disease: An Experience of 346 Patients

BACKGROUND AND OBJECTIVES

Moyamoya disease (MMD) is a steno-occlusive disease treated with revascularization surgery. Craniotomy and multiple burr hole encephalogaleoperiosteal-synangiosis (EGPS) are used for revascularization of the anterior cerebral artery territory. The aim of this study was to compare the clinical outcome between the 2 surgical methods in pediatric patients with MMD.

METHODS

A retrospective review of patients with MMD who underwent bifrontal indirect bypass surgery was performed. Clinical features, perioperative data, and angiographic, perfusion, and functional outcomes were compared between the 2 groups. Propensity score matching was performed to compare the perioperative characteristics and clinical outcomes.

RESULTS

A total of 346 patients were included in this study, 111 patients underwent bifrontal craniotomy EGPS, and 235 patients had bifrontal multiple burr hole EGPS. An insignificant higher rate of postoperative infarction (11.7% vs 5.5%, P = .072) and more postoperative hemorrhage occurred in the craniotomy EGPS group (3.6% vs 0%, P = .004). Of the 83 patients selected with propensity score matching for each group, the duration of operation was shorter ( P < .001) and the amount of intraoperative bleeding was significantly less in the multiple burr hole EGPS group ( P = .008). There was no difference in clinical outcomes between the 2 groups.

CONCLUSION

Bifrontal multiple burr hole EGPS has benefits over craniotomy with shorter surgical time, less intraoperative bleeding, fewer postoperative complications, and comparable perfusion and functional outcomes. Multiple burr hole EGPS is a safe and effective method that might be considered for revascularization of the anterior cerebral artery territory in pediatric patients with MMD.

Monitoring Posterior Cerebral Perfusion Changes With Dynamic Susceptibility Contrast-Enhanced Perfusion MRI After Anterior Revascularization Surgery in Pediatric Moyamoya Disease

OBJECTIVE

To determine whether dynamic susceptibility contrast-enhanced (DSC) perfusion magnetic resonance imaging (MRI) can be used to evaluate posterior cerebral circulation in pediatric patients with moyamoya disease (MMD) who underwent anterior revascularization.

MATERIALS AND METHODS

This study retrospectively included 73 patients with MMD who underwent DSC perfusion MRI (age, 12.2 ± 6.1 years) between January 2016 and December 2020, owing to recent-onset clinical symptoms during the follow-up period after completion of anterior revascularization. DSC perfusion images were analyzed using a dedicated software package (NordicICE; Nordic NeuroLab) for the middle cerebral artery (MCA), posterior cerebral artery (PCA), and posterior border zone between the two regions (PCA-MCA). Patients were divided into two groups; the PCA stenosis group included 30 patients with newly confirmed PCA involvement, while the no PCA stenosis group included 43 patients without PCA involvement. The relationship between DSC perfusion parameters and PCA stenosis, as well as the performance of the parameters in discriminating between groups, were analyzed.

RESULTS

In the PCA stenosis group, the mean follow-up duration was 5.3 years after anterior revascularization, and visual disturbances were a common symptom. Normalized cerebral blood volume was increased, and both the normalized time-to-peak (nTTP) and mean transit time values were significantly delayed in the PCA stenosis group compared with those in the no PCA stenosis group in the PCA and PCA-MCA border zones. TTP_PCA (odds ratio [OR] = 6.745; 95% confidence interval [CI] = 2.665-17.074; P < 0.001) and CBV_PCA-MCA (OR = 1.567; 95% CI = 1.021-2.406; P = 0.040) were independently associated with PCA stenosis. TTP_PCA showed the highest receiver operating characteristic curve area in discriminating for PCA stenosis (0.895; 95% CI = 0.803-0.986).

CONCLUSION

nTTP can be used to effectively diagnose PCA stenosis. Therefore, DSC perfusion MRI may be a valuable tool for monitoring PCA stenosis in patients with 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.

Quantitative Optical Coherence Tomography Angiography in Patients with Moyamoya Vasculopathy: A Pilot Study

Moyamoya (MM) disease is a chronic cerebrovascular disease that can lead to progressive stenosis of the terminal portions of the internal carotid arteries and their proximal branches. We sought to investigate and quantify retinal vascular changes in patients with MM vasculopathy (MMV) using optical coherence tomography angiography (OCTA) compared to healthy controls. Our findings reveal retinal microvascular changes in patients with MMV and highlights the potential of OCTA imaging for the detection of subclinical retinal pathology.

Additional Revascularization Using Multiple Burr Holes for PCA Involvement in Moyamoya Disease

In specific cases of moyamoya disease (MMD), posterior cerebral artery (PCA) stenosis can develop after treatment of the anterior circulation and require additional revascularization. Here, we report two cases that underwent additional posterior indirect revascularization with multiple burr holes for PCA involvement after bilateral revascularization treatment of the anterior circulation. They presented with transient ischemic attack even after bilateral superficial temporal artery-middle cerebral artery bypass, and magnetic resonance angiography (MRA) showed that PCA stenosis had worsened. Indirect revascularization with multiple burr holes using Benz-marked skin incisions was performed. After surgery, the symptoms improved without perioperative complications, and cerebral angiography showed collateral circulation via the burr hole. Indirect revascularization for MMD is often combined with direct revascularization, and there are only a few reports on the use of multiple burr hole surgery alone. In addition, there are few reports of posterior circulation, despite the emphasis on the importance of PCA involvement in MMD. Indirect revascularization with multiple burr holes alone can be performed in multiple areas and applied to patients who cannot undergo direct revascularization using the occipital artery. The procedure is simple and less invasive than traditional direct revascularization procedures. Therefore, it can be effective, especially in pediatric cases of MMD with PCA involvement.

Occipital artery to middle cerebral artery bypass in pediatric moyamoya disease: rescue therapy after failed revascularization

OBJECTIVE

Patients with pediatric moyamoya disease (PMMD) showing recurrent symptoms or decreased cerebral blood flow after initial revascularization therapy may require additional revascularization to improve their clinical condition. The authors evaluated the clinical and hemodynamic benefits of an occipital artery (OA)-middle cerebral artery (MCA) bypass for patients with PMMD who have undergone an initial revascularization procedure.

METHODS

The authors retrospectively identified 9 patients with PMMD who had undergone OA-MCA bypass between March 2013 and December 2017, and who had received a previous superficial temporal artery-MCA bypass. The following clinical data were collected: initial revascularization procedure, symptoms (presence or recurrence), pre- and postoperative cerebral blood flow and cerebrovascular reactivity (CVR) changes, posterior cerebral artery (PCA) stenosis, PCA-related and nonrelated symptoms, and latest follow-up.

RESULTS

Preoperatively, all patients (n = 9) suffered non-PCA-related recurrent symptoms, and 4 had PCA-related symptoms. At 1-year follow-up, all patients with PCA-related symptoms showed complete recovery. Additionally, 8 (89%) patients with non-PCA symptoms experienced improvement. Only 1 (11%) patient showed no improvement after the surgical procedure. The mean pre- and postoperative CVR values of the MCA territory were 14.8% and 31.3%, respectively, whereas the respective mean CVR values of the PCA territory were 22.8% and 40.0%.

CONCLUSIONS

The OA-MCA bypass is an effective rescue therapy to improve the clinical condition and hemodynamic changes caused by PMMD in patients who experience recurrent symptoms after initial revascularization.

Late (5-20 years) outcomes after STA-MCA anastomosis and encephalo-duro-myo-arterio-pericranial synangiosis in patients with moyamoya disease

OBJECTIVE

Surgical revascularization is known to reduce the incidence of further ischemic and hemorrhagic events in patients with moyamoya disease, but the majority of previous studies report only short-term (< 5 years) outcomes. Therefore, in this study the authors aimed to evaluate late (5-20 years) outcomes of moyamoya patients after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass (encephalo-duro-myo-arterio-pericranial synangiosis [EDMAPS]).

METHODS

Cumulative incidences of late morbidity/mortality and disease progression were evaluated among 93 patients who underwent STA-MCA anastomosis and EDMAPS. All of the patients were prospectively followed up for longer than 5 years postsurgery (10.5 ± 4.4 years). There were 35 pediatric and 58 adult patients. Initial presentation included transient ischemic attack/ischemic stroke in 80 patients and hemorrhagic stroke in 10 patients, and 3 patients were asymptomatic. Surgery was performed in a total of 141 hemispheres. Follow-up MRI/MRA was performed within a 6- or 12-month interval during the follow-up periods.

RESULTS

During the follow-up periods, 92/93 patients were free from any stroke or death, but 1 patient had a recurrence of hemorrhagic stroke (0.10% per patient-year). Disease progression occurred in the territory of the contralateral carotid or posterior cerebral artery (PCA) in 19 hemispheres of 15 patients (1.5% per patient-year). The interval between initial surgery and disease progression varied widely, from 0.5 to 15 years. Repeat bypass surgery for the anterior and posterior circulation resolved ischemic attacks in all 10 patients.

CONCLUSIONS

The study results indicate that STA-MCA anastomosis and EDMAPS would be the best choice to prevent further ischemic and hemorrhagic stroke for longer than 10 years on the basis of the demonstrated widespread improvement in cerebral hemodynamics in both the MCA and ACA territories in the study patients. However, after 10 years postsurgery regular follow-up is essential to detect disease progression in the territory of the contralateral carotid artery and PCA and prevent late cerebrovascular events.

Preoperative neurodevelopment of children with moyamoya angiopathy

AIM

To preoperatively assess the neurodevelopment of a predominantly white population of children with moyamoya angiopathy (MMA).

METHOD

Assessments of 40 children with MMA (24 females, 16 males; mean age 6y 11mo, range 20mo-16y) included tests for non-verbal IQ and fine motor skills, and questionnaires on quality of life, behaviour, and executive functions. The Paediatric Stroke Outcome Measure (PSOM) score was evaluated by a paediatric neurologist.

RESULTS

Children with MMA had significantly lower non-verbal IQ scores (mean IQ 92.1, SD 19.6, p=0.015) and fine motor skills (z-score -1.84, p=0.004) than population norms. Patients with posterior cerebral artery (PCA) involvement had poorer non-verbal IQ scores than those without (79.6, SD 24.6 vs 95.2, SD 17.2, p=0.042). Higher PSOM scores were related to lower non-verbal IQ scores (Spearman's rank correlation coefficient -0.43, p=0.006), while the presence of stroke, bilaterality, disease versus syndrome, and age at diagnosis had no significant effect on non-verbal IQ. Quality of life, behaviour, and executive functions were in the typically developing range.

INTERPRETATION

Children with MMA are more likely to manifest intellectual and fine motor skill impairment before surgical intervention. PCA involvement is an additional risk factor for lower non-verbal IQ.

WHAT THIS PAPER ADDS

Children with moyamoya angiopathy have intellectual and fine motor skill impairment before surgical intervention. Posterior cerebral artery involvement and higher Paediatric Stroke Outcome Measure scores may predict poorer performance.

Transition to Adulthood for Pediatric Moyamoya Patients

Moyamoya is a progressive arteriopathy of the intracranial vasculature, predominantly affecting the terminal branches of the internal carotid artery. Treatment is predicated on surgical revascularization to reduce the risk of stroke. For patients diagnosed and treated as children, it is important to recognize the long-term implications of the disease, for example, that moyamoya is treatable, but not curable. Pediatric moyamoya patients face unique challenges as they transition to adulthood as a consequence of the chronic nature of this disorder. Successful long-term care requires a strategy that incorporates ongoing longitudinal disease monitoring, coordination of care between physician teams, and anticipation of socioeconomic factors that change over time. This article provides an approach to transition care to adult caregivers for pediatric moyamoya patients with a specific focus on the three key stakeholders in the process: the neurosurgeon, the primary care physician, and the individual patient.

Limits and pitfalls of indirect revascularization in moyamoya disease and syndrome

Moyamoya vasculopathy is a rare chronic cerebrovascular disorder characterized by the stenosis of the terminal branches of the internal carotid arteries and the proximal tracts of anterior and middle cerebral arteries. Although surgical revascularization does not significantly change the underlying pathogenic mechanisms, it plays a pivotal role in the management of affected individuals, allowing to decrease the risk of ischemic and hemorrhagic complications. Surgical approaches may be direct (extracranial-intracranial bypass), indirect, or a combination of the two. Several indirect techniques classifiable according to the tissue (muscle, periosteum, galea, dura mater, and extracranial tissues) or vessel (artery) used as a source of blood supply are currently available. In this study, we reviewed the pertinent literature and analyzed the advantages, disadvantages, and pitfalls of the most relevant indirect revascularization techniques. We discussed the technical aspects and the therapeutical implications of each procedure, providing a current state-of-the-art overview on the limits and pitfalls of indirect revascularization in the treatment of moyamoya vasculopathy.

Strategy and effect of repeat bypass surgery for anterior/posterior circulation in refractory moyamoya disease

OBJECTIVE

In this study the authors aimed to describe clinical features, surgical techniques, and long-term outcomes of repeat bypass surgery required for a certain subset of patients with moyamoya disease.

METHODS

The authors retrospectively reviewed a total of 22 repeat bypass surgeries for 20 patients (age range 1-69 years) performed during the last 20 years at their institutions. The patients were classified into 2 groups. Group A included 10 patients who underwent repeat bypass surgery for anterior circulation due to insufficient revascularization on the ipsilateral side. Group B included 10 patients who underwent repeat bypass surgery for posterior circulation due to the involvement of the posterior cerebral artery (PCA) after successful initial surgery for anterior circulation.

RESULTS

Preoperative symptoms included headache in 3 patients, transient ischemic attack in 10, cerebral infarction in 3, and intracranial hemorrhage in 4 patients. Intervals between the initial bypass surgery and repeat bypass surgery were 0.3-30 years (median 3 years). In group A, superficial temporal artery to middle cerebral artery (MCA) anastomosis and indirect bypass were performed on 7 hemispheres. Only indirect bypass was performed on 3 hemispheres because of the lack of suitable donor or recipient arteries. In group B, occipital artery (OA) to PCA anastomosis and indirect bypass were conducted on 4 hemispheres, and OA-MCA anastomosis and indirect bypass on 1 hemisphere. Only indirect bypass was conducted on 7 hemispheres because of the lack of suitable recipient arteries. All 22 repeat bypass surgeries were successfully conducted. During follow-up periods (median 4 years), none of the patients suffered repeat stroke except 1 patient who died of recurrent intracerebral hemorrhage 3 years after repeat bypass surgery for anterior circulation.

CONCLUSIONS

Repeat bypass surgery was feasible and effective to reduce further incidence of headache attack, transient ischemic attack, and ischemic/hemorrhagic stroke in moyamoya disease patients. Through precise radiological analysis, surgical procedures should be planned to yield maximal therapeutic effects.

Characteristics of Moyamoya Syndrome in Sickle-Cell Disease by Magnetic Resonance Angiography: An Adult-Cohort Study

Background: Sickle cell disease (SCD) can be complicated by moyamoya syndrome. Brain magnetic resonance angiography (MRA) is a non-invasive method to diagnose this syndrome and, steno-occlusion and moyamoya vessels (MMV) scores have been proposed to evaluate its severity. Previous studies of SCD moyamoya syndrome did not evaluate the severity according to MRA scores. The objective was to assess the characteristics of moyamoya syndrome in an adult cohort of SCD using these MRA scores.

Methods: Twenty-five SCD patients with moyamoya syndrome were included using MRA with 3D time of flight technique. We evaluate steno-occlusion score for each hemisphere (range 0–10) from: steno-occlusion severity of internal carotid (ICA) (0–3), anterior cerebral (ACA) (0–3), middle cerebral (MCA) (0–2), and posterior cerebral (PCA) (0–2) arteries. MMV score for each hemisphere (range 0–5) depended from 5 MMV areas: (1) anterior communicating artery (2) basal ganglia (3) ICA/MCA (4) posterior communicating artery/PCA (5) basilar artery.

Results: Eight patients (32%) showed unilateral moyamoya syndrome. ICA steno-occlusion was involved in 22 patients (88%), MCA in 23 patients (92%), ACA in 9 patients (36%), and PCA in 3 patients (12%). MMV involved ACoA area in 10 patients (40%), basal ganglia in 13 patients (52%), PCoA/PCA in 10 patients (40%), MCA/ICA in 7 patients (28%), and BA in 1 patient (4%). Steno-occlusion and MMV mean hemisphere scores were 3.4/10 (± 1.42) and 1.6/5 (± 0.71), respectively.

Conclusion: Frequent unilateral moyamoya syndrome, uncommon PCA involvement and, moderate steno-occlusion and MMV scores seem to be features of SCD moyamoya syndrome. In future studies, MRA scores could be collected to assess the follow-up in these patients.

Progress in moyamoya disease

Moyamoya disease is characterized by progressive stenosis or occlusion of the intracranial portion of the internal carotid artery and their proximal branches, resulting in ischemic or hemorrhagic stroke with high rate of disability and even death. So far, available treatment strategies are quite limited, and novel intervention method is being explored. This review encapsulates current advances of moyamoya disease on the aspects of epidemiology, etiology, clinical features, imaging diagnosis and treatment. In addition, we also bring forward our conjecture, which needs to be testified by future research.

Posterior cerebral artery stenosis and posterior circulation revascularization surgery in pediatric patients with moyamoya disease

OBJECTIVE Some pediatric patients with moyamoya disease (MMD) present with posterior cerebral artery (PCA) stenosis before and after anterior circulation revascularization surgery and require posterior circulation revascularization surgery. This study evaluated the factors associated with PCA stenosis and assessed the efficacy of posterior circulation revascularization surgery, including occipital artery (OA)-PCA bypass, in pediatric patients with MMD. METHODS The presence of PCA stenosis before and after anterior circulation revascularization surgery and its clinical characteristics were investigated in 62 pediatric patients (< 16 years of age) with MMD. RESULTS Twenty-three pediatric patients (37%) with MMD presented with PCA stenosis at the time of the initial diagnosis. A strong correlation between the presence of infarction and PCA stenosis before anterior revascularization was observed (p < 0.001). In addition, progressive PCA stenosis was observed in 12 patients (19.4%) after anterior revascularization. The presence of infarction and a younger age at the time of initial diagnosis were risk factors for progressive PCA stenosis after anterior revascularization (p < 0.001 and p = 0.002, respectively). Posterior circulation revascularization surgery, including OA-PCA bypass, was performed in 9 of the 12 patients with progressive PCA stenosis, all of whom showed symptomatic and/or radiological improvement. CONCLUSIONS PCA stenosis is an important clinical factor related to poor prognosis in pediatric MMD. One should be aware of the possibility of progressive PCA stenosis during the postoperative follow-up period and consider performing posterior circulation revascularization surgery.

Unique Angiographic Appearances of Moyamoya Disease Detected with 3-Dimensional Rotational Digital Subtraction Angiography Imaging Showing the Hemodynamic Status

BACKGROUND

The aim of this study was to identify the unique morphological arterial features in patients with moyamoya disease on 3-dimensional rotational digital subtraction angiography.

MATERIALS AND METHODS

One hundred seven hemispheres of 58 consecutive patients with moyamoya disease that were analyzed with fused 3-dimensional images of internal carotid angiograms and vertebral angiograms that were marked with different colors were reviewed. Angiographic findings in the posterior watershed area were classified, and the utility of the classification was analyzed by comparing it with clinical presentations and quantitative hemodynamic parameters obtained with positron emission tomography.

RESULTS

Two unique angiographic appearances were identified. A vacant vessel appearance (no arterial inflow despite absence of cortical infarction) was observed mostly in transient ischemic attack hemispheres. In hemispheres with a vacant vessel appearance, cerebral blood flow was decreased, cerebral blood volume was increased, and mean transit time was prolonged significantly (P = .00017, P = .0061, and P = .00026, respectively). A cocktail vessel appearance (mixture of carotid and vertebral arterial flow) was most commonly observed in asymptomatic cases, as well as in ischemic hemispheres. Cerebral blood volume increased and mean transit time was prolonged significantly (P = .036 and P = .014, respectively) in hemispheres with a cocktail vessel appearance. The trend of progression in hemodynamic severity in the order of normal appearance, cocktail vessel appearance, and vacant vessel appearance in the watershed area was statistically significant.

CONCLUSION

Fused 3-dimensional digital subtraction angiography demonstrated unique angiographic features in the watershed area, and this represented the degree of cerebral hemodynamic impairment in moyamoya disease.

Impaired Collateral Vessel Formation in Sickle Cell Disease

OBJECTIVE

The adaptive response to vascular injury is the formation of functional collateral vessels to maintain organ integrity. Many of the clinical complications associated with sickle cell disease can be attributed to repeated bouts of vascular insufficiency, yet the detailed mechanisms of collateral vessel formation after injury are largely unknown in sickle cell disease. Here, we characterize postischemic neovascularization in sickle cell disease and the role of neutrophils in the production of reactive oxygen species.

APPROACH AND RESULTS

We induced hindlimb ischemia by ligation of the femoral artery in Townes SS (sickle cell) mice compared with AA (wild type) mice. Perfusion recovery, ascertained using LASER (light amplification by stimulated emission of radiation) Doppler perfusion imaging, showed significant diminution in collateral vessel formation in SS mice after hindlimb ischemia (76±13% AA versus 34±10% in SS by day 28; P<0.001; n=10 per group). The incidence of amputation (25% versus 5%) and foot necrosis (80% versus 15%) after hindlimb ischemia was significantly increased in the SS mice. Motor function recovery evaluation by the running wheel assay was also impaired in SS mice (36% versus 97% at 28 days post-hindlimb ischemia; P<0.001). This phenotype was associated with persistent and excessive production of reactive oxygen species by neutrophils. Importantly, neutrophil depletion or treatment with the antioxidant N-acetylcysteine reduced oxidative stress and improved functional collateral formation in the SS mice.

CONCLUSIONS

Our data suggest dysfunctional collateral vessel formation in SS mice after vascular injury and provide a mechanistic basis for the multiple vascular complications of sickle cell disease.

Assessment of the cortical artery using computed tomography angiography for bypass surgery in moyamoya disease

Computed tomography angiography (CTA) is often used to assess the vascular status in moyamoya disease. The purpose of the study is to identify the characteristics of cortical arteries (M4) of moyamoya disease on CTA; the clinical significance of which is also discussed. A total of 38 hemispheric sides of 27 patients with moyamoya disease were included in this study. The number of M4 was visualized on CTA using cortical surface imaging and compared between the moyamoya disease group and the non-moyamoya disease group or the control group. Then, the clinical and radiological factors associated with the number of M4, the distribution of M4, and collateral circulation were examined. The number of M4 was lower in the moyamoya disease group than in the non-moyamoya disease group and in the control group (p < 0.05). There are few predictive clinical factors of the number of M4 except male sex. The prefrontal artery, precentral artery, central artery, and angular artery had a significantly higher prevalence in moyamoya disease (p < 0.05). The durocortical and periventricular anastomosis had a significantly higher prevalence in moyamoya disease (p < 0.05). The prevalence and distribution pattern of cortical arteries in moyamoya disease differed from that of the non-moyamoya disease group, and the distribution patterns of M4 might be influenced by collateral circulation. It is thus essential to recognize M4 to assess the recipient artery so as to ensure superficial temporal artery-middle cerebral artery bypass.

Direct Anastomosis Using Occipital Artery for Additional Revascularization in Moyamoya Disease After Combined Superficial Temporal Artery–Middle Cerebral Artery and Indirect Bypass

BACKGROUND: The posterior cerebral artery (PCA) is involved in approximately 30% of moyamoya disease (MMD) cases. However, there have been insufficient reports describing revascularization techniques in the posterior portion of the brain, particularly of direct anastomosis.

OBJECTIVE: To perform a technical assessment in patients with MMD who underwent either occipital artery (OA)–PCA bypass or OA–middle cerebral artery (MCA) bypass.

METHODS: A total of 428 revascularization procedures in 368 patients were retrospectively assessed by reviewing clinical charts and radiological data.

RESULTS: Ten patients (3.5%) were treated with direct bypass after the anterior revascularization with a median interval of 30 months (range, 5 months-16 years). Seven patients were &lt; 18 years of age (average age, 17.5 ± 15.6 years). Preoperative symptoms included transient motor deficits involving the lower extremities (n = 5), visual disturbances (n = 6), and cerebral infarctions (n = 6). A favorable outcome (modified Rankin Scale score &lt; 3) was achieved in 9 of these 10 patients. Direct anastomosis was performed in 3 hemispheres with an OA-MCA bypass and in 8 hemispheres with an OA-PCA bypass. Patency of the direct bypass was confirmed on angiogram in 7 of 7 patients who underwent conventional angiogram performed within 1 year after the surgery. None of the 10 patients demonstrated cerebral infarctions after the posterior revascularization.

CONCLUSION: In MMD, symptomatic PCA regression after anterior revascularization was found predominantly in children and young adults. Direct anastomosis in the posterior portion of the brain can be successfully achieved and is effective in preventing ischemic events.

Posterior Cerebral Artery Insufficiency in Pediatric Moyamoya Disease

The majority of clinical studies on moyamoya disease (MMD) have focused on anterior circulation. The disease involvement of posterior circulation in MMD, mainly in the posterior cerebral artery (PCA), has been mentioned since the early 1980s, and it has been repeatedly emphasized as one of the most important factors related to poor prognosis in MMD. However, its clinical features and outcome have only been elucidated during the last few years. In this review, the angiographic definition of PCA stenosis is summarized. The clinical features are elucidated as being either early-onset or delayed-onset, according to the time of PCA stenosis diagnosis in reference to the anterior circulation revascularization surgeries. The surgical strategy and hypothesis on the mechanism of PCA stenosis is also briefly mentioned. It appears that some MMD patients may show PCA stenosis during the early or late course of the disease and that the presenting symptoms may vary. Because the hemodynamic compromise caused by PCA stenosis may respond well to surgical treatment, clinicians should be aware of the condition, especially during follow-up of MMD patients.