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Regression of periventricular anastomosis after indirect revascularization in pediatric patients with moyamoya disease

Elizabeth Yi Zheng, Shoko Hara, Motoki Inaji, Yoji Tanaka, Tadashi Nariai, and Taketoshi Maehara


The aim of this study was to evaluate whether indirect revascularization in pediatric patients with moyamoya disease leads to periventricular anastomosis (PVA) regression, which is markedly developed in moyamoya vessels and is regarded as a risk factor for hemorrhage.


Pediatric patients with moyamoya disease treated with indirect revascularization from 2011 to 2021 were included in this study. Magnetic resonance angiography and arterial spin labeling images acquired before and 1 year after surgery were assessed to obtain a visual scale of postoperative collateral artery formation, moyamoya vessels, PVA, and quantitative values of cerebral blood flow (CBF). The relationship between background information (age, sex, RNF213 p.R4810K variant status, and preoperative CBF) and postoperative collateral artery formation, as well as postoperative CBF improvement and regression of moyamoya vessels and PVA, was evaluated.


Of 89 hemispheres in 58 patients (34 females; mean [SD] patient age 8.0 [3.4] years), 74.2% showed good postoperative collateral artery formation and a significant increase in CBF (p < 0.001). Postoperative PVA showed significant regression (postoperative score 1.46 [1.06] vs 2.02 [1.69], p = 0.001), especially in those arising from choroidal arteries (postoperative score 0.28 [0.50] vs 0.72 [0.67], p < 0.001). Compared with hemispheres without good collateral artery formation, those with good collateral artery formation were more likely to show a higher increase in CBF (9.74 [12.44] ml/min/100 g vs −4.86 [9.68] ml/min/100 g, p < 0.001) and regression of PVA (54.5% [36/66] vs 30.4% [7/23], p = 0.015). Although not statistically significant, patients with postoperative PVA progression were younger than those with regression (6.75 [3.03] years vs 8.18 [3.17] years, p = 0.188), and patients with the RNF213 p.R4810K variant were more likely to show regression (28/57 [49.1%] hemispheres vs 5/13 [38.5%] hemispheres, p = 0.069).


Indirect revascularization in pediatric patients with moyamoya disease resulted in good collateral extracranial artery formation and an increase in CBF and PVA regression, especially of vessels arising from choroidal arteries. With good postoperative collateral artery development, patients were more likely to show improved CBF and regression of moyamoya vessels, including PVA. Whether postoperative PVA changes reduce future hemorrhage risk requires further investigation.

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Long-term follow-up of surgically treated juvenile patients with moyamoya disease

Clinical article

Maki Mukawa, Tadashi Nariai, Yoshiharu Matsushima, Yoji Tanaka, Motoki Inaji, Taketoshi Maehara, Masaru Aoyagi, and Kikuo Ohno


Surgical revascularization is considered an effective treatment for juvenile patients with moyamoya disease (MMD). Yet the long-term outcome in surgically treated patients still needs to be clarified. More than 30 years have passed since the authors' department started intensively treating pediatric patients with MMD using indirect anastomosis techniques. In this study the authors surveyed the current status of these patients.


Activities of daily living (ADLs) were surveyed and present clinical status was assessed based on the modified Rankin Scale (mRS). Cerebrovascular events subsequent to surgical treatment were also recorded.


Since 1979, 208 patients younger than 19 years of age with MMD were surgically treated and followed up for > 3 years. Data were available on 172 patients (83%), who had been followed up for a mean of 14.3 years (range 3–32 years). Activity of daily living outcomes were as follows: 138 patients (80.2%) had mRS scores of 0–2, 29 (16.9%) a score of 3, 1 (0.6%) a score of 4, 1 (0.6%) a score of 5, and 3 (1.7%) a score of 6. Cerebrovascular events occurred 8 or more years after surgery in 6 patients (3.4%), that is, 6 hemorrhages and 3 infarctions. The cumulative risk of late-onset stroke at 10, 20, and 30 years after surgical intervention was 0.8%, 6.3%, and 10.0%, respectively.


This long-term survey demonstrated that most surgically treated pediatric patients with MMD maintain good ADL outcomes. However, a significant number of new cerebrovascular events occurred more than 10 years after the initial surgery. Additional follow-up will help to identify which events may occur during the adult years of patients treated as children.

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Absence of the RNF213 p.R4810K variant may indicate a severe form of pediatric moyamoya disease in Japanese patients

Shoko Hara, Maki Mukawa, Hiroyuki Akagawa, Thiparpa Thamamongood, Motoki Inaji, Yoji Tanaka, Taketoshi Maehara, Hidetoshi Kasuya, and Tadashi Nariai


The authors’ objective was to investigate the influence of the RNF213 p.R4810K variant on the clinical presentation and outcomes of Japanese pediatric patients with moyamoya disease.


A total of 129 Japanese patients with pediatric-onset moyamoya disease (onset age ≤ 15 years) who visited the authors’ department from 2012 to 2020 participated in this study. After RNF213 p.R4810K genotyping of each patient was performed, the relationship between genotype and clinical presentation or outcomes, including onset age, initial presentation, surgical outcomes, and subsequent cerebrovascular events, was evaluated. Patients without the p.R4810K variant were tested for RNF213 variants other than p.R4810K. The authors especially focused on the results of patients who presented with moyamoya disease at younger than 1 year of age (infantile onset).


Compared with the patients with heterozygous variants, patients without the p.R4810K variant were younger at onset (7.1 ± 3.7 vs 4.4 ± 0.9 years), and all 4 patients with infantile onset lacked the p.R4810K variant. A greater proportion of patients without the p.R4810K variant presented with infarction than patients with the heterozygous variant (24.0% vs 7.6%) and a decreased proportion presented with transient ischemic attack (36.0% vs 71.7%). No significant correlation was observed between p.R4810K genotype and clinical outcomes, including surgical outcomes and subsequent cerebrovascular events; however, a decreased proportion of patients without the p.R4810K variant had good surgical outcomes compared with that of patients with the heterozygous variant (76.5% vs 92.2%). Among the 25 patients without the p.R4810K variant, 8 rare variants other than p.R4810K were identified. Three of 4 patients with infantile onset had RNF213 variants other than p.R4810K, which had a more severe functional effect on this gene than p.R4810K.


Absence of the RNF213 p.R4810K variant may be a novel biomarker for identification of a severe form of pediatric moyamoya disease.

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First autopsy analysis of a neovascularized arterial network induced by indirect bypass surgery for moyamoya disease: case report

Maki Mukawa, Tadashi Nariai, Motoki Inaji, Natsumi Tamada, Taketoshi Maehara, Yoshiharu Matsushima, Kikuo Ohno, Mariko Negi, and Daisuke Kobayashi

The object of this study was to analyze the pathology of collateral vessels newly induced by indirect bypass surgery for moyamoya disease (MMD). An autopsy analysis was conducted on a 39-year-old woman with MMD who had died of a brainstem infarction. The patient had undergone bilateral indirect bypass surgeries 22 years earlier. Sufficient revascularization via bilateral external carotid arterial systems was confirmed by cerebral angiography before her death. Macroscopic observation of the operative areas revealed countless meandering vessels on the internal surface of the dura mater connected with small vessels on the brain surface and in the subpial brain tissue. Notably, microscopic analysis of these vessels revealed the characteristic 3-layer structure of an arterial wall. This autopsy analysis was the first to confirm that indirect bypass surgery had induced the formation of a new arterial network (arteriogenesis) and that this network had been maintained for more than 20 years to compensate for the chronic cerebral ischemia caused by the MMD.