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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., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Treatment for moyamoya disease in infants and toddlers is challenging, because of the progressiveness of the disease. Revascularization surgery is the first-line therapy and should be performed as early as possible after diagnosis to prevent additional cerebral infarction. This review describes in detail the changes in the new "Diagnostic Criteria 2021 for moyamoya disease", and discusses the concept of treatment including indirect and combined bypass surgery in infants and toddlers. Surgical technique and perioperative management based on our experience are also precisely described.

We previously reported a patient with cerebral proliferative angiopathy (CPA) who showed cerebral ischemia in resting and acetazolamide-stressed N-isopropyl-p-[ 123 I] iodoamphetamine single-photon emission computed tomography ( 123 I-IMP-SPECT). At onset, the patient was treated conservatively. However, during the 2 years following initial onset, his hemiparesis and aphasia had gradually aggravated and his IQ scores were markedly decreased. MRI revealed progressive vascular proliferation and brain atrophy. 123 I-IMP-SPECT showed more severely impaired cerebral blood flow (CBF) and cerebrovascular reactivity over the affected hemisphere. We performed an indirect revascularization to augment CBF; however, his neurological deficits were not improved and new arteriovenous shunts via extracranial-intracranial bypass were developed, followed by an asymptomatic small intracerebral hemorrhage. There are no reports on CPA patients who have shown cerebral hemorrhage after indirect revascularization. Treatments for CPA are still challenging and controversial. Cases with severe stenosis of the proximal arteries may benefit from indirect revascularization. But indirect bypass should not be indicated for such patients without main arterial stenosis, even if they have persistent ischemia., (Copyright © 2018. Published by Elsevier Inc.)

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.

Moyamoya disease can be associated with a rapidly progressive course in young patients. This report describes a patient with moyamoya disease who experienced rapid disease progression, resulting in cerebral infarction and a wide area of diminished cerebral perfusion. Double superficial temporal artery (STA)-middle cerebral artery (MCA) anastomoses were utilized to immediately increase cerebral perfusion in the affected area. This case involved a 5-year-old girl who had been diagnosed with moyamoya disease and had undergone STA-MCA anastomosis with indirect bypass in the right hemisphere at the age of 3. At the time of presentation, magnetic resonance (MR) imaging showed cerebral infarction at the left frontal lobe, and MR angiography showed rapidly progressive narrowing of the left MCA that had not been present 3 months prior. N-isopropyl-p-[I123] iodoamphetamine single-photon emission computed tomography (IMP-SPECT) showed markedly decreased uptake in the left hemisphere. She underwent emergent STA-MCA double anastomoses with indirect bypass on the left side. IMP-SPECT showed marked increase in uptake in the left hemisphere. The anterior cerebral artery (ACA) territory adjacent to the cerebral infarction also showed increased uptake on the SPECT. Postoperatively, there were no clinical or radiographic indications of ischemic or hemorrhagic complications. Double anastomoses are effective in quickly and significantly increasing blood flow. The postoperative course in this case was uneventful. Double anastomoses are a surgical option for patients with moyamoya disease who show rapid disease progression, even in those in the acute phase of cerebral infarction.

Objective: In patients with moyamoya disease, surgery to revascularize the ischemic brain is a recommended treatment. However, there are a few patients who require additional revascularization surgery because of progression of the disease. Even patients who show no postoperative ischemic symptoms at first may experience late deterioration. We performed additional surgery for such lesions using occipital artery (OA)-posterior cerebral artery (PCA) bypass with indirect revascularization. The efficacy of the procedure is reported., Methods: We treated 3 patients with moyamoya disease who showed a transient ischemic attack after revascularization surgery. Three female patients, ranging in age from 6.0 to 35.2 years (mean age, 23.8 years) at the time of surgery, with ischemic symptoms (leg monoparesis in 2, visual impairment in 1) underwent the additional revascularization procedure. Preoperatively, all patients underwent indirect and/or direct revascularization surgery for initial treatment. All patients showed progression of the disease, especially in the PCA. OA-PCA bypass with encephalogaleodurosynangiosis and burr hole surgery were performed for postoperative ischemic symptoms., Results: All patients showed clinical and radiological improvement. The transient ischemic attack was improved in all 3 patients. They did not complain of transient ischemic attack in the recent follow-up period. Follow-up magnetic resonance imaging showed no additional cerebral infarction. Magnetic resonance angiography showed widening of the OA and development of peripheral collateral vessels. Postoperative single-photon emission computed tomographic studies showed marked increase of uptake in both anterior cerebral artery and PCA territories. Cerebral vasodilatory capacity evaluated by an acetazolamide test also showed marked improvement. One patient showed postoperative cerebral edema as a result of focal cerebral hyperperfusion., Conclusion: OA-PCA anastomosis with indirect revascularization was effective for postoperative ischemia that showed symptoms in the anterior cerebral artery and PCA territories as a result of progression of a PCA lesion.

In the surgical treatment of childhood Moyamoya disease, we have been performing a new non-anastomotic bypass surgery using encephalo-galeo-myo-synangiosis (EGMS) with dural pedicle insertion over the brain surface. To assess the results obtained using this procedure, the long-term clinical outcome and the characteristics of cerebral blood flow and oxygen metabolism using PET were evaluated. The subjects were 19 patients with childhood Moyamoya disease admitted to our institution over 8 years from 1988 to 1996. This type of surgery was performed 39 times and the patients have been followed up from 10 months to 8 years. Preoperatively, although cerebral blood flow and oxygen metabolism were varied from individual to individual, low values of regional cerebral blood flow (rCBF) and regional cerebral metabolic rate of oxygen (rCMRO2) with relatively high values of regional oxygen extraction fraction (rOEF) were found in the frontal region in most of the patients compared to normal children. Postoperatively, obvious improvement of cerebral blood flow and hemodynamics in all the areas in the operative site and clinical symptoms and signs ameliorated or disappeared during the follow-up period. In conclusion, the present method appeared to be useful to improve the hemodynamic in the brain and its long-term clinical outcome was satisfactory.

A case of chronic subdural hematoma following EMS (Encephalo-Myo-Synangiosis) for moyamoya disease was presented. Two and a half year-old girl was admitted to our division because of right hemiparesis. Left carotid angiography revealed a very narrow left carotid bifurcation and small moyamoya vessels. EMS was performed on the left side and a right hemiparesis was improved. But she developed a headache and vomiting one month after the operation. CT scan and angiogram showed a chronic subdural hematoma on the left side. A hematoma weighing approximately 30 g was evacuated. We reviewed a similar case of 5-year-old boy in the literature and discussed the mechanism accounting for formation of the chronic subdural hematoma following EMS.