Ivy sign, misery perfusion, and asymptomatic moyamoya disease: FLAIR imaging and (15)O-gas positron emission tomography

Enhancement of the Ivy Sign during an Ischemic Event in Moyamoya Disease

We herein report a case of increased and expanded ipsilateral ivy sign paralleling the expansion of cerebral infarction in a patient with moyamoya disease. A 67-year-old woman visited our hospital with symptoms of left hemiplegia, left homonymous hemianopia, and left unilateral spatial neglect. Magnetic resonance imaging of the head showed cerebral infarction in the right parietal lobe. In addition, ivy signs were evident on fluid-attenuated inversion recovery imaging. These findings were enhanced by the expansion of cerebral infarction and disappeared once the ischemia resolved, implying hemodynamic changes. As a result of continuing medical treatment without antithrombotic therapy, the patient obtained a good outcome. Treatment for moyamoya disease in the acute phase is considered to require complex knowledge of multiple factors, such as the anatomical background of the individual patient and the progression grade of ischemia.

European Stroke Organisation (ESO) Guidelines on Moyamoya angiopathy: Endorsed by Vascular European Reference Network (VASCERN)

The European Stroke Organisation (ESO) guidelines on Moyamoya Angiopathy (MMA), developed according to ESO standard operating procedure and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology, were compiled to assist clinicians in managing patients with MMA in their decision making. A working group involving neurologists, neurosurgeons, a geneticist and methodologists identified nine relevant clinical questions, performed systematic literature reviews and, whenever possible, meta-analyses. Quality assessment of the available evidence was made with specific recommendations. In the absence of sufficient evidence to provide recommendations, Expert Consensus Statements were formulated. Based on low quality evidence from one RCT, we recommend direct bypass surgery in adult patients with haemorrhagic presentation. For ischaemic adult patients and children, we suggest revascularization surgery using direct or combined technique rather than indirect, in the presence of haemodynamic impairment and with an interval of 6–12 weeks between the last cerebrovascular event and surgery. In the absence of robust trial, an Expert Consensus was reached recommending long-term antiplatelet therapy in non-haemorrhagic MMA, as it may reduce risk of embolic stroke. We also agreed on the utility of performing pre- and post- operative haemodynamic and posterior cerebral artery assessment. There were insufficient data to recommend systematic variant screening of RNF213 p.R4810K. Additionally, we suggest that long-term MMA neuroimaging follow up may guide therapeutic decision making by assessing the disease progression. We believe that this guideline, which is the first comprehensive European guideline on MMA management using GRADE methods will assist clinicians to choose the most effective management strategy for MMA.

Profile of precipitating factors and its implication in 160 Indian patients with Moyamoya angiopathy

INTRODUCTION

Moyamoya angiopathy (MMA) has been known to manifest with myriad of neurological manifestations, often in association with various precipitating factors. This is the first study to systematically analyze the precipitating triggers to neurological symptoms done on the largest cohort of MMA in India.

METHODS

A single-centered, cross-sectional observational study, recruiting 160 patients with consecutive angiographically proven MMA over a period of 5 years (2016-2021), was undertaken to evaluate the profile of immediate precipitating factors in temporal association to the neurological symptoms, along with their clinical and radiological characteristics. SPSS 25 was used for statistical analysis.

RESULTS

Among the 160 patients (Adult-85, children-75), precipitating factors were seen in 41.3%, significantly higher in children (52%) than adults (31.8%) (p value: 0.011). The commonest triggers included fever (18.8%), emotional stress (8.1%), heavy exercise and diarrhea (6.3% each). Cold bath triggered MMA symptoms in 1.3%. Fever (p value: 0.008) and persistent crying (p value: 0.010) triggered neurological symptoms more commonly in children than in adults. Amongst MMA patients with precipitating factors, the commonest MMA presentation included cerebral infarction type (37.9%) and TIA (31.8%). The majority of precipitating factors that preceded an ischemic event were BP-lowing ones (54.7%).

CONCLUSION

Neurological symptoms of MMA are commonly associated with several precipitating factors, including the lesser known triggers like cold bath. The frequency and profile precipitating factors varies with the age of presentation and type of MMA. It can serve as an early clue to the diagnosis of MMA and its careful avoidance can be largely beneficial in limiting the distressing transient neurological symptoms.

Ivy sign: a diagnostic and prognostic biomarker for pediatric moyamoya

OBJECTIVE

Ivy sign is a radiographic finding on FLAIR MRI sequences and is associated with slow cortical blood flow in moyamoya. Limited data exist on the utility of the ivy sign as a diagnostic and prognostic tool in pediatric patients, particularly outside of Asian populations. The authors aimed to investigate a modified grading scale with which to characterize the prevalence and extent of the ivy sign in children with moyamoya and evaluate its efficacy as a biomarker in predicting postoperative outcomes, including stroke risk.

METHODS

Pre- and postoperative clinical and radiographic data of all pediatric patients (21 years of age or younger) who underwent surgery for moyamoya disease or moyamoya syndrome at two major tertiary referral centers in the US and Israel, between July 2009 and August 2019, were retrospectively reviewed. Ivy sign scores were correlated to Suzuki stage, Matsushima grade, and postoperative stroke rate to quantify the diagnostic and prognostic utility of ivy sign.

RESULTS

A total of 171 hemispheres in 107 patients were included. The median age at the time of surgery was 9 years (range 3 months-21 years). The ivy sign was most frequently encountered in association with Suzuki stage III or IV disease in all vascular territories, including the anterior cerebral artery (53.7%), middle cerebral artery (56.3%), and posterior cerebral artery (47.5%) territories. Following surgical revascularization, 85% of hemispheres with Matsushima grade A demonstrated a concomitant, statistically significant reduction in ivy sign scores (OR 5.3, 95% CI 1.4-20.0; p = 0.013). Postoperatively, revascularized hemispheres that exhibited ivy sign score decreases had significantly lower rates of postoperative stroke (3.4%) compared with hemispheres that demonstrated no reversal of the ivy sign (16.1%) (OR 5.5, 95% CI 1.5-21.0; p = 0.008).

CONCLUSIONS

This is the largest study to date that focuses on the role of the ivy sign in pediatric moyamoya. These data demonstrate that the ivy sign was present in approximately half the pediatric patients with moyamoya with Suzuki stage III or IV disease, when blood flow was most unstable. The authors found that reversal of the ivy sign provided both radiographic and clinical utility as a prognostic biomarker postoperatively, given the statistically significant association with both better Matsushima grades and a fivefold reduction in postoperative stroke rates. These findings can help inform clinical decision-making, and they have particular value in the pediatric population, as the ability to minimize additional radiographic evaluations and tailor radiographic surveillance is requisite.

What and why: the current situation and future prospects of "ivy sign" in moyamoya disease

“Ivy sign” is a special imaging manifestation of moyamoya disease (MMD), which shows continuous linear or punctate high intensity along the cortical sulci and subarachnoid space on magnetic resonance images. Ivy sign was reported to reflect the development of compensatory collaterals, and to be closely related to hemodynamic changes and clinical symptoms, and to indicate the postoperative prognosis, in MMD patients. It is a unique and critical marker for MMD. However, due to the lack of consistent criteria, such as definition, grading, and identification standards, ivy sign has not received much attention. We undertook a comprehensive literature search and summarized the current situation regarding ivy sign in MMD in terms of baseline characteristics, detection methods, definition, regional division and distribution patterns, grading criterions, incidence, related factors, the mechanism of ivy sign, and the effects of treatments. We also provided related concerns raised and future prospects relevant to studies about ivy sign in MMD.

Arterial transit artifacts observed by arterial spin labeling in Moyamoya disease

OBJECTIVES

Arterial spin labeling (ASL) is a magnetic resonance imaging (MRI) technique used to assess cerebral perfusion. When tissue perfusion is impaired, such as in Moyamoya disease, a hyperintense band called the arterial transit artifact (ATA) may occur, which interferes with accurate measurements on ASL-MRI. In this study, we evaluated the correlation of ATAs with magnetic resonance angiography (MRA) and single-photon emission computed tomography (SPECT) imaging results in Moyamoya disease. The aim of our study was to elucidate the pathophysiology of ATAs and risk factors for high ATA scores.

MATERIALS AND METHODS

This retrospective study included 28 patients (56 hemispheres) with Moyamoya disease treated at our institution. MRI, MRA, ASL perfusion, and N-isopropyl-[¹²³I] b-iodoamphetamine (¹²³I-IMP) SPECT were performed. In order to semi-quantitatively evaluate the degree of ATA, the ATA scores were measured according to the number of hyperintense signal bands in the cerebral cortex. The relationship between the ATA scores and clinical and radiological factors were analyzed.

RESULTS

Regional cerebral blood flow (rCBF) determined with ASL weakly correlated with that determined by ¹²³I-IMP SPECT (ρ=0.31, p=0.027). There was no significant association between the ATA scores and rCBF values determined with ¹²³I-IMP SPECT (p=0.872, 0.745, 0.743 at PLD1000 (post-labeling delay), 1500, and 2000, respectively). However, there was a significant correlation between ATA scores and MRA scores (ρ=0.427 p=0.001; ρ=0.612 p=0.001; ρ=0.563 p=0.001 at PLD1000, 1500, and 2000, respectively). An analysis of patient background characteristics revealed a significantly higher incidence of high ATA scores in female patients, patients with high MRA scores, and patients with a distinguishable ivy sign. A multivariate analysis confirmed that female sex, high MRA score, and presence of an ivy sign were risk factors for high ATA scores.

CONCLUSION

ATA scores were moderately correlated with MRA scores, and presence of an ivy sign was the most predictive factor for high ATA scores. A high ATA score determined using ASL in a patient with Moyamoya disease might suggest an advanced disease stage and a reduction in cerebrovascular reserve capacity.

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.

Imaging of Moyamoya Disease and Moyamoya Syndrome: Current Status

Moyamoya disease (MMD) and Moyamoya syndrome (MMS) are referring to a progressive steno-occlusive vasculopathy at terminal portions of the bilateral internal carotid arteries and their proximal branches with prominent collateral artery formation. They can be found throughout the world and cause irreversible damage to the cerebral hemodynamics due to the progressive nature. Prompt diagnosis and accurate assessment could significantly improve the prognosis of MMD and MMS. Some imaging modalities could be used for diagnosis and nonquantitative evaluation of MMD and MMS, such as conventional computed tomography (CT) and magnetic resonance imaging (MRI), digital subtraction angiography, CT angiography (CTA), and magnetic resonance angiography. Some could quantitatively evaluate the cerebral hemodynamics of MMD and MMS, such as single-photon emission CT, positron emission tomography, xenon-enhanced CT, perfusion CT, dynamic susceptibility contrast MRI, arterial spin labeling MRI, and the hemodynamic parameters measured by those imaging methods could guide treatment of MMD and MMS. All the imaging modalities have their merits and demerits, and they can play a part in certain situation. We need establish standardized protocols for preoperative and postoperative evaluation with different imaging techniques in the further science for MMD and MMS.

Cerebrovascular Reactivity Measured with ASL Perfusion MRI, Ivy Sign, and Regional Tissue Vascularization in Moyamoya

BACKGROUND

Arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) may be used to determine brain regions at risk for ischemia in patients with moyamoya vasculopathy and to identify patients who may benefit from surgical revascularization. We aimed to investigate whether 1) the severity of moyamoya is related to the presence of leptomeningeal collaterals and cerebrovascular reactivity (CVR), 2) the presence of collaterals and ivy sign reflects disturbed CVR, and 3) arterial transit artefacts (ATAs) and ivy sign reflect the presence of collaterals.

METHODS

We determined severity of moyamoya on digital subtraction angiography (DSA) according to the modified Suzuki classification in 20 brain regions and scored regional tissue revascularization using a 4-point scale. Regional CVR and ATAs were assessed on ASL perfusion MRI, ivy sign on fluid attenuation inversion recovery MRI.

RESULTS

In 11 patients (median age 36 years; 91% female), we studied 203 regions. ATAs were associated with the presence of collaterals on DSA (P < 0.01). Of all regions with clearly visible collateral vessels on DSA, however, only 24% had ATAs. Ivy sign was not related to the presence or absence of collaterals nor to CVR. In 10% of regions with good vascularization on DSA, CVR was poor or showed steal.

CONCLUSIONS

ATAs were associated with the presence of collaterals on DSA. Although DSA vascularization scores correlated with CVR, 10% of regions with good vascularization on DSA had absent CVR or steal on ASL-MRI. DSA and ivy sign did not provide adequate information on the hemodynamic status of brain tissue in patients with moyamoya vasculopathy.

Prevalence of and risk factors for enlarged perivascular spaces in adult patients with moyamoya disease

Background

Enlarged perivascular spaces (EPVS) are often observed with magnetic resonance imaging in patients with small vessel disease. However, the risk factors, radiological features, and clinical relevance of EPVS in patients with moyamoya disease are poorly understood. The purpose of this study was to evaluate EPVS, the risk factors of many EPVS, and the pathophysiology of EPVS in adult patients with moyamoya disease.

Methods

One hundred cerebral hemispheres of 50 adult patients with moyamoya disease were examined. The control group consisted of 50 age/sex-matched patients without ischemic disease. The numbers of EPVS at the level of the centrum semiovale per hemisphere were compared between the moyamoya disease and control groups. In each hemisphere, the total numbers of EPVS were categorized into five grades (0–4), and the clinical and radiological characteristics of the predictive factors in patients in the high EPVS grade group (EPVS grade = 4) were assessed.

Results

The EPVS counts and grades were significantly higher in the moyamoya disease group. Analyses of the background characteristics of the patients with moyamoya disease revealed that significantly higher prevalence of high EPVS grades were associated with the female sex, hypertension, high magnetic resonance angiography scores, high numbers of flow voids in the basal ganglia, high brain atrophy scores, ivy signs, and white matter lesions. A logistic multivariate analysis of the patients with high EPVS grades revealed significant associations with the female sex, hypertension, and flow voids in the basal ganglia.

Conclusions

Increased EPVS were confirmed in adult patients with moyamoya disease, and the associated clinical and radiological factors were identified. The presence of hypertension, the female sex, and flow voids in the basal ganglia were important for predicting high EPVS grades in patients with moyamoya disease. Reductions in arterial pulsations with steno-occlusive changes can inhibit the flow of interstitial fluid, which can increase the number of EPVS in patients with moyamoya disease. Other clinical factors, such as the female sex and hypertension, may promote secondary brain damage in patients with moyamoya disease. Further evaluations of EPVS in patients with moyamoya disease are needed to better understand their pathophysiological importance.

Pathophysiological consideration of medullary streaks on FLAIR imaging in pediatric moyamoya disease

OBJECTIVE Medullary streaks detected on fluid-attenuated inversion recovery (FLAIR) imaging have been considered to be reflected ischemic regions in pediatric moyamoya disease. The purpose of this study was to evaluate these medullary streaks both clinically and radiologically and to discuss associated pathophysiological concerns. METHODS The authors retrospectively reviewed data from 14 consecutive pediatric patients with moyamoya disease treated between April 2009 and June 2016. Clinical and radiological features and postoperative imaging changes were analyzed. In 4 patients, hyperintense medullary streaks on FLAIR imaging (HMSF) at the level of the centrum semiovale were detected. RESULTS The HMSF were coincident with hyperintense medullary streaks on a T2-weighted image, though they were not completely coincident with the vasculature on either a T2*-weighted image or contrast-enhanced CT. Analysis revealed significantly higher values in terms of MR angiography scores, number of flow voids of the basal ganglia, and the presence of the medullary artery in the group with HMSF than in those without. In contrast, the presence of white matter damage was significantly less frequent in the HMSF group. All HMSF disappeared after surgery, and the mean apparent diffusion coefficient at the same level was significantly reduced postoperatively. CONCLUSIONS Although HMSF should be associated with collateral circulation in moyamoya disease, other factors may be involved, including stagnated cerebrospinal fluid or vasogenic edema that is relevant to the impaired state of the white matter. Findings in this study provide insight into the pathophysiological basis of the perivascular space in moyamoya disease.

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.