Moyamoya Periventricular Choroidal Collateral Registry-A Multicenter Cohort Study of Moyamoya Disease with Choroidal Anastomosis: Study Protocol.

Recent cohort studies on hemorrhagic and asymptomatic moyamoya disease have revealed that choroidal anastomosis, a type of fragile periventricular collateral pathway (periventricular anastomosis) typical of the disease, is an independent predictor of hemorrhagic stroke. However, treatment strategies for less-symptomatic nonhemorrhagic patients with choroidal anastomosis remain unclear. The Moyamoya Periventricular Choroidal Collateral (P-ChoC) Registry is an ongoing multicentered observational study that will test the hypothesis that extracranial-intracranial bypass prevents de novo hemorrhagic stroke in less symptomatic, nonhemorrhagic patients with choroidal anastomosis and may thus contribute to improving the prognosis of moyamoya disease. In this study, we report the study protocol of the moyamoya P-ChoC Registry and review the literature on choroidal anastomosis as a fragile collateral pathway.

RNF213 Mutation Associated with the Progression from Middle Cerebral Artery Steno-Occlusive Disease to Moyamoya Disease.

Middle cerebral artery steno-occlusive disease (MCAD) has been recognized as a different clinical entity from moyamoya disease (MMD). Although MCAD can progress to MMD, the extent to which patients actually progress and the risk factors for this progression have not been fully elucidated. We retrospectively reviewed patients with MCAD who underwent RNF213 genotyping. Demographic features, RNF213 p.R4810K mutation, medical history, and longitudinal changes in angiography were analyzed. Sixty patients with 81 affected hemispheres were enrolled. During the follow-up period, 17 patients developed MMD, and the RNF213 p.R4810K mutation was the only factor significantly associated with progression to MMD (odds ratio, 16.1; 95% CI, 2.13-731; P = 0.001). The log-rank test demonstrated that patients with the mutation had a higher risk of progression to MMD (P = 0.007), stenosis progression (P = 0.010), and symptomatic cerebral infarction or hemorrhage (P = 0.026). In Cox regression analysis the p.R4810K mutation remained a significant factor after adjusting for age group (childhood or adult onset) at diagnosis (hazard ratio, 8.42; 95% CI, 1.10-64.4). Hemisphere-based analysis also showed that the mutation was associated with a higher risk of progression to the MMD hemisphere (P = 0.002), stenosis progression (P = 0.005), and cerebral infarction or hemorrhage (P = 0.012). The RNF213 p.R4810K mutation was identified as a risk factor for progression from MCAD to MMD. Genotyping for this mutation may contribute to risk stratification in MCAD.

Vessel wall MRI in moyamoya disease: arterial wall enhancement varies depending on age, arteries, and disease progression.

OBJECTIVE: To investigate the relationship of followings for patients with moyamoya disease (MMD): arterial wall enhancement on vessel wall MRI (VW-MRI), cross-sectional area (CSA), time-of-flight MR angiography (MRA), age, locations from intracranial internal carotid artery (ICA) to proximal middle cerebral artery (MCA), disease progression, and transient ischemic attack (TIA). METHODS: Patients who underwent VW-MRI between October 2018 and December 2020 were enrolled in this retrospective study. We measured arterial wall enhancement (enhancement ratio, ER) and CSA at five sections of ICA and MCA. Also, we scored MRA findings. Multiple linear regression (MLR) analysis was performed to explore the associations between ER, age, MRA score, CSA, history of TIA, and surgical revascularization. RESULTS: We investigated 102 sides of 51 patients with MMD (35 women, 16 men, mean age 31 years ± 18 [standard deviation]). ER for MRA score 2 (signal discontinuity) was higher than ER for other scores in sections D (end of ICA) and E (proximal MCA) on MLR analysis. ER in section E was significantly higher in patients for MRA score 2 with TIA history than without. ER significantly increased as CSA increased in section E, which suggests ER becomes less in decreased CSA due to negative remodeling. CONCLUSION: Arterial wall enhancement in MMD varies by age, location, and disease progression. Arterial wall enhancement may be stronger in the progressive stage of MMD. Arterial wall enhancement increases with history of TIA at proximal MCA, which may indicate the progression of the disease. CLINICAL RELEVANCE STATEMENT: Arterial wall enhancement in moyamoya disease varies by age, location of arteries, and disease progression, and arterial wall enhancement may be used as an imaging biomarker of moyamoya disease. KEY POINTS: It has not been clarified what arterial wall enhancement in moyamoya disease represents. Arterial wall enhancement in moyamoya disease varies by age, location of arteries, and disease progression. Arterial wall enhancement in moyamoya disease increases as the disease progresses.

Posterior cerebral artery involvement in unilateral moyamoya disease is exclusively ipsilateral and influenced by RNF213 mutation gene dose: The SUPRA Japan study: PCA involvement in unilateral moyamoya.

OBJECTIVES: The characteristics and clinical implications of posterior cerebral artery (PCA) involvement in unilateral moyamoya disease (U-MMD), such as laterality, frequency of the RNF213 p.R4810K mutation, and clinical outcomes, have not been well studied. POPULATION AND METHODS: We analyzed a cohort of 93 patients with U-MMD who participated in the SUPRA Japan study. Clinical characteristics and radiological examinations were collected from medical records. The presence of the p.R4810K mutation was determined using a TaqMan assay. The clinical outcome was assessed using the modified Rankin Scale (mRS). Univariate and multivariate logistic regression analyses were performed to assess the associations. RESULTS: Among the patients with U-MMD, PCA involvement was observed in 60.0 % (3/5) of patients with homozygous mutation, 11.3 % (7/62) of those with heterozygous mutation, and 3.8 % (1/26) of those with wild type, showing a significant linear trend (p < 0.001 for trend). PCA involvement was observed exclusively on the same side as the affected anterior circulation. Dyslipidemia and cerebral infarction at initial onset were independently associated with mRS ≥1. Hypertension was associated with mRS ≥1 and it was also linked to infarction at initial onset, suggesting a potential confounding effect. Although PCA involvement showed a trend for higher mRS, it was not statistically significant. CONCLUSIONS: Our findings indicate a gene dose effect of the p.R4810K mutation on PCA involvement, with the homozygous state showing the most significant effect. Both genetic and modifiable factors such as dyslipidemia may influence the progression of U-MMD.

"Transcallosal" periventricular anastomosis in moyamoya disease: the fourth periventricular anastomosis and a potential predictor of hemorrhage.

OBJECTIVES: Choroidal anastomosis is a risk factor for hemorrhage in moyamoya disease. One variant of choroidal anastomosis, "transcallosal anastomosis," originates from the medial posterior choroidal artery, and penetrates the corpus callosum to reconstruct the pericallosal artery. We aimed to investigate the prevalence and the bleeding rate of transcallosal anastomosis using sliding thin-slab maximum intensity projection reformatted from magnetic resonance angiography (MRA). MATERIALS AND METHODS: This study included 222 patients. We defined transcallosal anastomosis grades (0-2) and the stenosis of the anterior (ACA, 0-2), middle (MCA, 1-3), and posterior cerebral artery (PCA, 0-2) by MRA scores, independently by two coauthors. RESULTS: Grade-2 transcallosal anastomosis was detected in 21 patients (9.5 %). There were no correlations of the incidence of transcallosal anastomosis with previous bypass surgery (P = 0.23). Multivariate analysis revealed a significantly higher incidence in hemorrhagic onset and younger age (odds ratio [OR] 3.77, and 0.97). Transcallosal anastomosis had statistically significant correlation with ACA and PCA scores (P = 0.01 and 0.03), but not with MCA scores (P = 0.1). In multivariate analysis, ACA scores 1 and 2 were significantly higher (OR, 15.44 and 11.17), and PCA score 1 was also higher (OR, 3.07), but PCA score 2 was not. Interrater agreement for judgment of transcallosal anastomosis grade was strong (κ = 0.89). Two patients with Grade-2 transcallosal anastomosis had late hemorrhage in the corpus callosum (bleeding rate: 2.5 % per year). CONCLUSIONS: Transcallosal anastomosis may be associated with both advanced ACA and moderate PCA stenosis, and cause hemorrhage at the corpus callosum.

Five-Year Stroke Risk and Its Predictors in Asymptomatic Moyamoya Disease: Asymptomatic Moyamoya Registry (AMORE).

BACKGROUND: Long-term outcomes are unknown in patients with asymptomatic moyamoya disease. In this report, we aimed to clarify their 5-year risk of stroke and its predictors. METHODS: We are conducting a multicenter, prospective cohort study (Asymptomatic Moyamoya Registry) in Japan. Participants were eligible if they were 20 to 70 years, had bilateral or unilateral moyamoya disease, experienced no episodes suggestive of TIA and stroke; and were functionally independent (modified Rankin Scale score 0-1). Demographic and radiological information was collected at enrollment. In this study, they are still followed up for 10 years. In this interim analysis, we defined the primary end point as a stroke occurring during a 5-year follow-up period. Independent predictors for stroke were also determined, using a stratification analysis method. RESULTS: Between 2012 and 2015, we enrolled 109 patients, of whom 103 patients with 182 involved hemispheres completed the 5-year follow-up. According to the findings on DSA and MRA, 143 hemispheres were judged as moyamoya disease and 39 hemispheres as questionable manifestations (isolated middle cerebral artery stenosis). The patients with questionable hemispheres were significantly older, more often male, and more frequently had hypertension than those with moyamoya hemisphere. Moyamoya hemispheres developed 7 strokes, including 6 hemorrhagic and 1 ischemic stroke, during the first 5 years. The annual risk of stroke was 1.4% per person, 0.8% per hemisphere, and 1.0% per moyamoya hemisphere. Independent predictor for stroke was Grade-2 choroidal anastomosis (hazard ratio, 5.05 [95% CI, 1.24-20.6]; P=0.023). Furthermore, microbleeds (hazard ratio, 4.89 [95% CI, 1.13-21.3]; P=0.0342) and Grade-2 choroidal anastomosis (hazard ratio, 7.05 [95% CI, 1.62-30.7]; P=0.0093) significantly predicted hemorrhagic stroke. No questionable hemispheres developed any stroke. CONCLUSIONS: The hemispheres with asymptomatic moyamoya disease may carry a 1.0% annual risk of stroke during the first 5 years, the majority of which are hemorrhagic stroke. Grade-2 choroidal anastomosis may predict stroke, and the microbleeds and Grade-2 choroidal anastomosis may carry the risk for hemorrhagic stroke. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: UMIN000006640.

Detecting immunoglobulin G4-related intracranial arteriopathy with magnetic resonance vessel wall imaging: a preliminary experience in two cases.

BACKGROUND: Detecting immunoglobulin G4 (IgG4)-related intracranial arteriopathy, a rare neurovascular complication of IgG4-related disease, is challenging. While magnetic resonance (MR) vessel wall imaging (VWI) can visualize various neurovascular pathologies, its application to this arteriopathy has not been reported as of this writing. CASE PRESENTATION: A 74-year-old male and a 65-year-old female manifested multiple cranial nerve palsy and neck pain, respectively. Both cases exhibited multiorgan masses with markedly elevated serum IgG4 levels and were clinically diagnosed with IgG4-related disease. Three-dimensional T1-weighted black blood VWI with and without contrast agent identified intracranial vascular lesions characterized as nearly-circumferential mural thickening with homogeneous contrast enhancement in the internal carotid and vertebral arteries; some of the lesions had been unrecognized with screening MR angiography due to expansive remodeling. The former patient underwent corticosteroid therapy, and VWI after treatment revealed decreased mural thickening and enhancement. CONCLUSION: Further studies to elucidate characteristic findings of VWI might contribute to early detection of this treatable pathology.

Increased abundance of Ruminococcus gnavus in gut microbiota is associated with moyamoya disease and non-moyamoya intracranial large artery disease.

Moyamoya disease (MMD) is a rare cerebrovascular disease endemic in East Asia. The p.R4810K mutation in RNF213 gene confers a risk of MMD, but other factors remain largely unknown. We tested the association of gut microbiota with MMD. Fecal samples were collected from 27 patients with MMD, 7 patients with non-moyamoya intracranial large artery disease (ICAD) and 15 control individuals with other disorders, and 16S rRNA were sequenced. Although there was no difference in alpha diversity or beta diversity between patients with MMD and controls, the cladogram showed Streptococcaceae was enriched in patient samples. The relative abundance analysis demonstrated that 23 species were differentially abundant between patients with MMD and controls. Among them, increased abundance of Ruminococcus gnavus > 0.003 and decreased abundance of Roseburia inulinivorans < 0.002 were associated with higher risks of MMD (odds ratio 9.6, P = 0.0024; odds ratio 11.1, P = 0.0051). Also, Ruminococcus gnavus was more abundant and Roseburia inulinivorans was less abundant in patients with ICAD than controls (P = 0.046, P = 0.012). The relative abundance of Ruminococcus gnavus or Roseburia inulinivorans was not different between the p.R4810K mutant and wildtype. Our data demonstrated that gut microbiota was associated with both MMD and ICAD.

Neuroimaging at 7 Tesla: a pictorial narrative review.

Neuroimaging using the 7-Tesla (7T) human magnetic resonance (MR) system is rapidly gaining popularity after being approved for clinical use in the European Union and the USA. This trend is the same for functional MR imaging (MRI). The primary advantages of 7T over lower magnetic fields are its higher signal-to-noise and contrast-to-noise ratios, which provide high-resolution acquisitions and better contrast, making it easier to detect lesions and structural changes in brain disorders. Another advantage is the capability to measure a greater number of neurochemicals by virtue of the increased spectral resolution. Many structural and functional studies using 7T have been conducted to visualize details in the white matter and layers of the cortex and hippocampus, the subnucleus or regions of the putamen, the globus pallidus, thalamus and substantia nigra, and in small structures, such as the subthalamic nucleus, habenula, perforating arteries, and the perivascular space, that are difficult to observe at lower magnetic field strengths. The target disorders for 7T neuroimaging range from tumoral diseases to vascular, neurodegenerative, and psychiatric disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy, major depressive disorder, and schizophrenia. MR spectroscopy has also been used for research because of its increased chemical shift that separates overlapping peaks and resolves neurochemicals more effectively at 7T than a lower magnetic field. This paper presents a narrative review of these topics and an illustrative presentation of images obtained at 7T. We expect 7T neuroimaging to provide a new imaging biomarker of various brain disorders.

Long Sylvian Approach for Proximal Middle Cerebral Artery Aneurysm.

This case involved a 66-year-old woman with unruptured proximal middle cerebral artery (MCA) aneurysm that had been found 4 years earlier and followed up with annual magnetic resonance imaging examinations. Considering several risk factors for rupture, such as increasing size and irregular shape of the aneurysm, we offered clipping surgery (Video 1). Preoperative 3-dimensional digital subtraction angiography demonstrated an irregularly shaped aneurysm 6 mm in maximum diameter with multiple daughter sacs. Preoperative magnetic resonance imaging clearly showed that the aneurysm dome was buried in the posterior orbital gyrus. Left pterional craniotomy was performed with a long-distance dissection through the sylvian fissure from the distal M2 segment of the MCA to the internal carotid artery to achieve proximal control. The irregularly shaped aneurysm was completely isolated from the circulation with multiple miniclips under motor evoked potential monitoring with a subdural electrode. Doppler ultrasonography and indocyanine green confirmed complete clipping and patent flow through the MCA bifurcation. Postoperative 3-dimensional computed tomography angiography confirmed no aneurysm filling, and diffusion-weighted imaging demonstrated no ischemic complications. Depending on the positional relationship of the aneurysm and limen insulae, different surgical procedures for head positioning, distance of Sylvian fissure dissection, and securing the site for proximal control are essential for safe clipping of MCA aneurysms.

Lack of Association between Seropositivity of Vasculopathy-Related Viruses and Moyamoya Disease.

OBJECTIVES: Although the association between genetic factors, such as RNF213 mutations, and moyamoya disease (MMD) has been well investigated, environmental factors are largely undetermined. Thus, we aimed to examine whether viral infection increases the risk of MMD. MATERIALS AND METHODS: To eliminate the effect of presence or absence of the RNF213 p.R4810K mutation, the entire study population was positive for this mutation. We collected whole blood from 111 patients with MMD (45 familial and 66 sporadic cases) and 67 healthy volunteers, and we measured the immunoglobulin G titer of 11 viruses (cytomegalovirus, varicella-zoster virus, measles virus, rubella virus, herpes simplex virus, mumps virus, Epstein-Barr virus, human parvovirus B19, human herpesvirus 6 [HHV6], human herpesvirus 8, and John Cunningham virus) that were presumed to be associated with vasculopathy using the enzyme-linked immunosorbent assay. Positivity for past viral infection was determined by cut-off values obtained from previous reports and the manufacturer's instructions, and the positive rate was compared between cases and age- and sex-matched controls. We performed familial case-specific and sporadic case-specific analyses, as well as a case-control analysis. RESULTS: There was no significant difference in the positive rate between the case group and the control group in any of the analyses. A significant difference was only observed in the combined case-control analysis for HHV6 (p = 0.046), but the viral antibody-positive rate in control individuals was higher than in MMD cases. CONCLUSIONS: Our cross-sectional study suggest that the investigated 11 viruses including HHV6 are unlikely to have an impact on MMD development.

Evaluation of moyamoya disease in CT angiography using ultra-high-resolution computed tomography: Application of deep learning reconstruction.

PURPOSE: The aim of this study was to examine the evaluation of ultra-high-resolution computed tomography angiography (UHR CTA) images in moyamoya disease (MMD) reconstructed with hybrid iterative reconstruction (Hybrid-IR), model-based iterative reconstruction (MBIR), and deep learning reconstruction (DLR). METHODS: This retrospective study with institutional review board approval included patients with clinically suspected MMD who underwent UHR CTA between January 2018 and July 2020. CTA images were reconstructed with three reconstruction methods. Qualitative visualization was evaluated in comparison with digital subtraction angiography. Quantitative evaluation included assessment of edge sharpness, full width at half maximum (FWHM), vessel contrast, and tissue signal-to-noise ratio (SNRtissue). One-way analysis of variance was used to analyze differences. In addition, reconstruction time were assessed. RESULTS: Qualitative evaluation of CTA for 33 sides did not differ significantly between reconstruction methods. In quantitative evaluation for 54 patients, edge sharpness for right and left cortical segments of the middle cerebral artery was significantly higher for Hybrid-IR than for other reconstructions. No significant difference was seen between MBIR and DLR. Edge sharpness for STA-MCA bypass was significantly higher for Hybrid-IR than for MBIR, but no significant difference was seen between Hybrid-IR and DLR. FWHM for STA-MCA showed no significant difference between the three reconstruction methods. DLR displayed the highest SNRtissue. The time required for reconstruction was 40 s for Hybrid-IR, 2580 s for MBIR, and 180 s for DLR. CONCLUSION: UHR CTA with DLR adequately visualized vessels in patients with MMD within a clinically feasible reconstruction time.

Characterization of Moyamoya and Middle Cerebral Artery Diseases by Carotid Canal Diameter and RNF213 p.R4810K Genotype.

OBJECTIVES: It is sometimes difficult to differentiate middle cerebral artery disease from moyamoya disease because the two can present similarly yet have different treatment strategies. We investigated whether the presence of a narrow carotid canal and the RNF213 mutation can help differentiate between the two phenotypes. POPULATION AND METHODS: We analyzed 78 patients with moyamoya disease, 27 patients with middle cerebral artery disease, and 79 controls from 2 facilities. The carotid canal diameter was measured using computed tomography. The p.R4810K mutation was genotyped by TaqMan assay. A receiver operating characteristics analysis was performed to assess the significance of the carotid canal diameter for the accurate diagnosis of moyamoya disease. RESULTS: The carotid canal diameter was significantly narrower in patients with moyamoya disease than in controls. The optimal cutoff values were 5.0 mm for adult males and 4.5 mm for adult females and children (sensitivity: 0.82; specificity: 0.92). Among the patients with middle cerebral artery disease, 18.5% and 25.0% of the affected hemispheres had the p.R4810K mutation and narrow canal (i.e., below the cutoff), respectively, whereas only 3.1% of those had both. Contrastingly, 68.8% of the affected hemispheres in patients with moyamoya disease had both these characteristics. Among the patients with moyamoya disease, those with the p.R4810K mutation tended to have narrower carotid canals. CONCLUSIONS: Although the presence of a narrow carotid canal or the p.R4810K mutation alone could not be used to distinguish those with moyamoya disease from those with middle cerebral artery disease, the combination of these factors could better characterize the two phenotypes.

Characterizing the neurocognitive profiles of children with moyamoya disease using the Das Naglieri cognitive assessment system.

Although cognitive impairment is well-documented in children with moyamoya disease (MMD), selective decline in specific neurocognitive domains remains controversial. The purpose of this study was to characterize the neurocognitive profile of children with MMD using the Das Naglieri Cognitive Assessment System (CAS) and the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV). We analyzed the neurocognitive data of 30 children (median age, 7 years) with MMD who were assessed with the CAS and the WISC-IV before surgery. We focused on the comparison of standard scores and intraindividual differences across domains. The CAS scores significantly varied across four measures (standard scores, p < 0.001; intraindividual differences, p < 0.001). Post-hoc analyses revealed that the standard scores and intraindividual differences for successive processing were significantly lower than those for planning and attention. The WISC-IV scores did not significantly vary among the four measures, although the working memory index was the lowest among the four measures. The within-individual weakness in successive processing, a form of working memory function, may be a distinct characteristic of children with MMD. The CAS may be more sensitive than the WISC-IV for detecting this selective neurocognitive weakness in children with MMD.

Genetic and nongenetic factors for contralateral progression of unilateral moyamoya disease: the first report from the SUPRA Japan Study Group.

OBJECTIVE: Although many studies have analyzed risk factors for contralateral progression in unilateral moyamoya disease, they have not been fully elucidated. The aim of this study was to examine whether genetic factors as well as nongenetic factors are involved in the contralateral progression. METHODS: The authors performed a multicenter cohort study in which 93 cases with unilateral moyamoya disease were retrospectively reviewed. The demographic features, RNF213 R4810K mutation, lifestyle factors such as smoking and drinking, past medical history, and angiographic findings were analyzed. A Cox proportional hazards model was used to find risk factors for contralateral progression. RESULTS: Contralateral progression was observed in 24.7% of cases during a mean follow-up period of 72.2 months. Clinical characteristics were not significantly different between 67 patients with the R4810K mutation and those without it. Cox regression analysis showed that the R4810K mutation (hazard ratio [HR] 4.64, p = 0.044), childhood onset (HR 7.21, p < 0.001), male sex (HR 2.85, p = 0.023), and daily alcohol drinking (HR 4.25, p = 0.034) were independent risk factors for contralateral progression. CONCLUSIONS: These results indicate that both genetic and nongenetic factors are associated with contralateral progression of unilateral moyamoya disease. The findings would serve to help us better understand the pathophysiology of moyamoya disease and to manage patients more appropriately.

Quiet Diffusion-weighted MR Imaging of the Brain for Pediatric Patients with Moyamoya Disease.

PURPOSE: Diffusion-weighted MRI (DWI) is an essential sequence for evaluating pediatric patients with moyamoya disease (MMD); however, acoustic noise associated with DWI may lead to motion artifact. Compared with conventional DWI (cDWI), quiet DWI (qDWI) is considered less noisy and able to keep children more relaxed and stable. This study aimed to evaluate the suitability of qDWI compared with cDWI for pediatric patients with MMD. METHODS: In this observational study, MR examinations of the brain were performed either with or without sedation in pediatric patients with MMD between September 2017 and August 2018. Three neuroradiologists independently evaluated the images for artifacts and restricted diffusion in the brain. The differences between qDWI and cDWI were compared statistically using a chi-square test. RESULTS: One-hundred and six MR scans of 56 patients with MMD (38 scans of 15 sedated patients: 6 boys and 9 girls; mean age, 5.2 years; range, 1-9 years; and 68 scans of 42 unsedated patients: 19 boys and 23 girls; mean age, 10.7 years; range, 7-16 years) were evaluated. MR examinations were performed either with or without sedation (except in one patient). In sedated patients, no artifact other than susceptibility was observed on qDWI, whereas four artifacts were observed on cDWI (P = .04). One patient awoke from sedation during cDWI scanning, while no patient awoke from sedation during qDWI acquisition. For unsedated patients, three scans showed artifacts on qDWI, whereas two scans showed artifacts on cDWI (P = .65). Regarding restricted diffusion, qDWI revealed three cases, while two cases were found on cDWI (P = .66). CONCLUSION: qDWI induced fewer artifacts compared with cDWI in sedated patients, and similar frequencies of artifacts were induced by qDWI and by cDWI in unsedated patients. qDWI showed restricted diffusion comparable to cDWI.

Plasticity of the bony carotid canal and its clinical use for assessing negative remodeling of the internal carotid artery.

BACKGROUND AND OBJECTIVE: It has long been believed that the bony carotid canal has no plasticity and that a small canal represents a hypoplastic internal carotid artery. We aimed to show whether the carotid canal can narrow according to morphological changes in the internal carotid artery. MATERIALS AND METHODS: The carotid canal diameter was longitudinally measured in seven individuals who underwent carotid artery ligation. As moyamoya disease is known to be associated with negative remodeling of the internal carotid artery, the carotid canal diameter was measured in 106 patients with moyamoya disease, and an association with the outer diameter of the internal carotid artery or a correlation with the disease stage was investigated. The carotid canal was measured by computed tomography (106 patients), and the outer diameter of the artery was measured by high-resolution magnetic resonance imaging (63 patients). The carotid canal area was calculated by the product of the maximum axial diameter and its perpendicular diameter. RESULTS: All seven patients who underwent carotid artery ligation showed narrowing of the carotid canal, and the carotid canal area decreased by 12.2%-28.9% during a mean follow-up period of 4.2 years. In patients with moyamoya disease, the carotid canal area showed a linear correlation with the outer area of the internal carotid artery (r = 0.657, p < 0.001), and a negative correlation with the disease stage (ρ = -0.283, p < 0.001). CONCLUSION: The bony carotid canal has plasticity, and its area reflects the outer area of the internal carotid artery, therefore, it can be used to assess the remodeling of the carotid artery. A narrow carotid canal may not necessarily indicate hypoplastic internal carotid artery.

[Moyamoya Disease].

In this educational article for young neurosurgeons, the author highlights the characteristic CT and MRI findings for diagnosing moyamoya disease. The author also provides guidelines for the systematic interpretation of angiographic findings in patients with moyamoya disease.

Successful shrinkage of anterior communicating artery aneurysm after ACA-ACA bypass with interposed occipital artery graft in pediatric moyamoya disease: illustrative case.

BACKGROUND: Selecting therapeutic options for moyamoya disease (MMD)-associated anterior communicating artery (ACoA) aneurysm, a rare pathology in children, is challenging because its natural course remains unclear. OBSERVATIONS: A 4-year-old boy exhibiting transient ischemic attacks was diagnosed with unilateral MMD accompanied by an unruptured ACoA aneurysm. Although superficial temporal artery to middle cerebral artery anastomosis eliminated his symptoms, the aneurysm continued to grow after surgery. Since a previous craniotomy and narrow endovascular access at the ACoA precluded both aneurysmal clipping and coil embolization, the patient underwent a surgical anastomosis incorporating an occipital artery graft between the bilateral cortical anterior cerebral arteries (ACAs). This was intended to augment blood flow in the ipsilateral ACA territory and to reduce the hemodynamic burden on the ACoA complex. The postoperative course was uneventful, and radiological images obtained 12 months after surgery revealed good patency of the bypass and marked shrinkage of the aneurysm in spite of the intact contralateral internal carotid artery. LESSONS: Various clinical scenarios should be assessed carefully with regard to this pathology. Bypass surgery aimed at reducing flow to the aneurysm might be an alternative therapeutic option when neither coiling nor clipping is feasible.