Computational fluid dynamics (CFD) assess biological systems based on specific boundary conditions. We propose modeling more advanced hemodynamic metrics, such as core line length (CL) and critical ...points which characterize complexity of flow in the context of cerebral vasculature, and specifically cerebral veins during the physiologically evolving early neonatal state of vein of Galen malformations (VOGM). CFD has not been applied to the study of arteriovenous shunting in Vein of Galen Malformations but could help illustrate the pathophysiology of this malformation.
Three neonatal patients with VOGM at Boston Children's Hospital met inclusion criteria for this study. Structural MRI data was segmented to generate a mesh of the VOGM and venous outflow. Boundary condition flow velocity was derived from PC-MR sequences with arterial and venous dual velocity encoding. The mesh and boundary conditions were applied to model the cerebral venous flow. We computed flow variables including mean wall shear stress (WSSmean), mean OSI, CL, and the mean number of critical points (nCrPointsmean) for each patient specific model. A critical point is defined as the location where the shear stress vector field is zero (stationary point) and can be used to describe complexity of flow.
The division of flow into the left and right venous outflow was comparable between PC-MR and CFD modeling. A high complexity recirculating flow pattern observed on PC-MR was also identified on CFD modeling. Regions of similar WSSmean and OSImean (<1.3 fold) in the left and right venous outflow channels of a single patient have several-fold magnitude difference in higher order hemodynamic metrics (> 3.3 fold CL, > 1.7 fold nCrPointsmean). Specifically, the side which developed JBS in each model had greater nCrPointsmean compared to the jugular bulb with no stenosis (VOGM1: 4.49 vs. 2.53, VOGM2: 1.94 vs. 0, VOGM3: 1 vs. 0). Biologically, these regions had subsequently divergent development, with increased complexity of flow associating with venous stenosis.
Advanced metrics of flow complexity identified in computational models may reflect observed flow phenomena not fully characterized by primary or secondary hemodynamic parameters. These advanced metrics may indicate physiological states that impact development of jugular bulb stenosis in VOGM.
Background
Donor vessel quality can impact the outcome of extracranial-intracranial (EC-IC) bypass. External carotid artery (ECA) disease may produce embolism into the anastomosis and cerebral ...territory and possibly reduce flow in the superficial temporal artery (STA). Previously reported remedies to ECA stenosis include ECA endarterectomy, stenting, and angioplasty.
Clinical presentation
A middle-aged patient with chronic left MCA occlusion, progressive ischemic symptoms on maximal medical therapy, and imaging confirmation of compromised hemodynamic reserve was evaluated for EC-IC bypass. Angiography demonstrated severe ECA origin stenosis. An ECA-ICA transposition was performed, primarily to eliminate the risk of emboli and secondarily to possibly improve the STA flow. The patient sustained an excellent radiological and clinical outcome, and the STA donor cut-flow was increased modestly by 22% (45 to 55 mL/min).
Conclusion
This case is the first report of an ECA to internal carotid artery transposition as an option in the management of ECA stenosis in preparation for an STA-MCA bypass for the purpose of flow augmentation.
Blue rubber bleb nevus syndrome (BRBNS) is a rare condition that presents with venous malformation blebs throughout the body, most commonly on the skin and gastrointestinal tract. There have only ...been a limited number of reports of benign BRBNS lesions involving the spine in children, which were detected after chronic symptomatology. We herein present a unique case of a ruptured BRBNS venous malformation into the epidural space of the lumbar spine in a child presenting with acute neurologic deficit and discuss the relevant surgical considerations for operating in the setting of BRBNS.
Background and Purpose
Fractal dimension is an objective metric for the notion of structural complexity. We sought to investigate differences in structural complexity between healthy and affected ...territories of cerebral vasculature in moyamoya, as well as associated scalp vasculature and native transdural collaterals in patients with moyamoya by comparing their respective fractal dimensions.
Methods
Our cohort consisted of 15 transdural collaterals from 12 patients with unilateral anterior circulation moyamoya. Frames of distal arterial vasculature from internal and external carotid angiograms were selected then automatically segmented and also manually annotated by a cerebrovascular surgeon. In the affected hemisphere, the region with transdural collateral supply was compared to the contralateral region. The resulting skeletonized angiograms were analyzed for their fractal dimensions.
Results
We found the average fractal dimension (Df) of the moyamoya-side ICA was 1.82 with slightly different means for the anteroposterial (AP) and lateral views (mean = 1.82; mean = 1.81). The overall mean for healthy cerebral vasculature was also found to be 1.82 (AP: mean = 1.83; lateral: mean = 1.81). Mean Df of native transdural collaterals was found to be 1.82 (AP: mean = 1.83; lateral: mean = 1.81). The mean Df difference between autosegmented and manually segmented images was 0.013.
Conclusion
In accordance with the clinical understanding of moyamoya disease, the distal arterial structural complexity is not affected in moyamoya, and is maintained by transdural collaterals formed by vasculogenesis. Autosegmentation of cerebral vasculature is also shown to be accurate when compared to manual segmentation.
Middle fossa arachnoid cysts (MFACs) are rare, congenital lesions that may rupture and cause symptoms of elevated intracranial pressure. We sought to describe the presence of and factors associated ...with optic nerve edema in MFACs, focusing on the utility of ophthalmologic evaluations for guiding cyst management.
We reviewed clinical and radiographic information for all patients with MFACs with ophthalmologic evaluations at our institution. Headache, cranial nerve palsy, emesis, altered mental status, fatigue, and seizures were considered MFAC-related symptoms. Univariate and multivariable analyses evaluated factors associated with optic edema.
Fifty-one patients between 2003 and 2022 were included. Cysts were a median volume of 169.9 cm3 (interquartile range: 70.5, 647.7). Evidence of rupture with subdural hematoma/hygroma occurred in 19 (37.3%) patients. Eighteen (35.3%) patients underwent surgery for their cyst and/or rupture-associated intracranial bleed. Eleven (21.6%) patients had optic edema; all were symptomatic and experienced cyst rupture. Ten of these patients received surgery. Postoperatively, optic edema resolved in 80% of cases. Cyst volume and symptoms were not associated with optic edema; however, patients with ruptured cysts, particularly those with traumatic rupture, were more likely to have optic edema and receive surgery (P < 0.001).
We found optic edema in 21.6% of evaluated MFACs, and this comprised of 57.9% of ruptured cases. Optic edema was not found in unruptured cysts. Cyst fenestration improved optic edema and patient symptoms. In conjunction with clinical history and neuroimaging, optic edema may help guide MFAC management, particularly in patients with cyst rupture.
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.
Purpose
Few guidelines exist for genetic testing of patients with moyamoya arteriopathy. This study aims to characterize the yield of genetic testing of non-syndromic moyamoya patients given the ...current pre-test probability.
Methods
All pediatric moyamoya patients who received revascularization surgery at one institution between 2018 and 2022 were retrospectively reviewed. Patients with previously diagnosed moyamoya syndromes or therapeutic cranial radiation were excluded.
Results
Of 117 patients with moyamoya, 74 non-syndromic patients (44 females, 59%) were eligible. The median age at surgery was 8.1 years. Neurosurgeons referred 18 (24%) patients for neurogenetic evaluation. Eleven (61%) patients subsequently underwent genetic testing. Eight (73%) patients had available testing results. Five (62.5%) of these patients had developmental delay compared to 16 (22%) of the entire cohort. Six (75%) patients who underwent genetic testing were found to have at least one genetic variant. These results led to diagnosis of a new genetic disorder for 1 (12.5%) patient and screening recommendations for 2 (25%) patients. An RNF213 variant in one patient led to recommendations for family member screening and pulmonary hypertension screening. Another patient was diagnosed with CBL disorder and referred for cancer screening. The median age at surgery in patients with clinically actionable findings was 4.6 years compared to 9.2 years in those who were referred for genetic testing. All 3 patients who had an actionable finding had developmental delay.
Conclusion
It may be beneficial to refer moyamoya patients under 5 for genetic screening given the high likelihood of discovering actionable mutations.
Machine learning (ML) has been increasingly used in medicine and neurosurgery. We sought to determine whether ML models can distinguish ruptured from unruptured aneurysms and identify features ...associated with rupture.
We performed a retrospective review of patients with intracranial aneurysms detected on vascular imaging at our institution between 2002 and 2018. The dataset was used to train 3 ML models (random forest, linear support vector machine SVM, and radial basis function kernel SVM). Relative contributions of individual predictors were derived from the linear SVM model.
Complete data were available for 845 aneurysms in 615 patients. Ruptured aneurysms (n = 309, 37%) were larger (mean 6.51 mm vs. 5.73 mm; P = 0.02) and more likely to be in the posterior circulation (20% vs. 11%; P < 0.001) than unruptured aneurysms. Area under the receiver operating curve was 0.77 for the linear SVM, 0.78 for the radial basis function kernel SVM models, and 0.81 for the random forest model. Aneurysm location and size were the 2 features that contributed most significantly to the model. Posterior communicating artery, anterior communicating artery, and posterior inferior cerebellar artery locations were most highly associated with rupture, whereas paraclinoid and middle cerebral artery locations had the strongest association with unruptured status.
ML models are capable of accurately distinguishing ruptured from unruptured aneurysms and identifying features associated with rupture. Consistent with prior studies, location and size show the strongest association with aneurysm rupture.
