A Combined Computational Fluid Dynamics and Arterial Spin Labeling MRI Modeling Strategy to Quantify Patient-Specific Cerebral Hemodynamics in Cerebrovascular Occlusive Disease

Cerebral hemodynamics in the presence of cerebrovascular occlusive disease (CVOD) are influenced by the anatomy of the intracranial arteries, the degree of stenosis, the patency of collateral pathways, and the condition of the cerebral microvasculature. Accurate characterization of cerebral hemodynamics is a challenging problem. In this work, we present a strategy to quantify cerebral hemodynamics using computational fluid dynamics (CFD) in combination with arterial spin labeling MRI (ASL). First, we calibrated patient-specific CFD outflow boundary conditions using ASL-derived flow splits in the Circle of Willis. Following, we validated the calibrated CFD model by evaluating the fractional blood supply from the main neck arteries to the vascular territories using Lagrangian particle tracking and comparing the results against vessel-selective ASL (VS-ASL). Finally, the feasibility and capability of our proposed method were demonstrated in two patients with CVOD and a healthy control subject. We showed that the calibrated CFD model accurately reproduced the fractional blood supply to the vascular territories, as obtained from VS-ASL. The two patients revealed significant differences in pressure drop over the stenosis, collateral flow, and resistance of the distal vasculature, despite similar degrees of clinical stenosis severity. Our results demonstrated the advantages of a patient-specific CFD analysis for assessing the hemodynamic impact of stenosis.

Perioperative Considerations for Revascularization and Non-Revascularization Surgeries in Moyamoya Disease

Moyamoya disease is a rare, progressive cerebrovascular occlusive disease; characterized by narrowing of the distal internal carotid arteries and their branches. The incidence is high in East Asians and most commonly presents in the first and fourth decade of life. Its symptoms are headaches, seizures, transient neurological deficits, and cognitive decline. Medical management is based on treating the symptoms and includes antiplatelet and anti-seizure medications. Surgical revascularization is the mainstay of treatment. Unique pathophysiology of moyamoya disease necessitates neuro-anesthesiologists to formulate an individualized plan perioperatively. The overriding goal of perioperative anesthetic management of moyamoya disease is to ensure optimal cerebral perfusion and protection. Maintenance of normotension, normocarbia, normo-oxygenation, normothermia, and euvolemia is the cornerstone during the perioperative period. Perioperative adequate analgesia is crucial to prevent cerebral ischemia and allows close neurological monitoring. This chapter reviews perioperative anesthetic management of patients with moyamoya disease.

A combined computational fluid dynamics and MRI Arterial Spin Labeling modeling strategy to quantify patient-specific cerebral hemodynamics in cerebrovascular occlusive disease

Cerebral hemodynamics in the presence of cerebrovascular occlusive disease (CVOD) are influenced by the anatomy of the intracranial arteries, the degree of stenosis, the patency of collateral pathways, and the condition of the cerebral microvasculature. Accurate characterization of cerebral hemodynamics is a challenging problem. In this work, we present a strategy to quantify cerebral hemodynamics using computational fluid dynamics (CFD) in combination with arterial spin labeling MRI (ASL). First, we calibrated patient-specific CFD outflow boundary conditions using ASL-derived flow splits in the Circle of Willis. Following, we validated the calibrated CFD model by evaluating the fractional blood supply from the main neck arteries to the vascular territories using Lagrangian particle tracking and comparing the results against vessel-selective ASL (VS-ASL). Finally, cerebral hemodynamics were assessed in two patients with CVOD and a healthy control subject. We demonstrated that the calibrated CFD model accurately reproduced the fractional blood supply to the vascular territories, as obtained from VS-ASL. The two patients revealed significant differences in pressure drop over the stenosis, collateral flow, and resistance of the distal vasculature, despite similar degrees of clinical stenosis severity. Our results demonstrated the advantages of a patient-specific CFD analysis for assessing the hemodynamic impact of stenosis.

Superficial-Temporal-Artery-To-Middle-Cerebral-Artery Bypass in Cerebrovascular Occlusive Disease and Hemodynamic-Related Ischemia: Illustrative Case and Literature Review

Stroke is the third most common cause of death worldwide. About 10% to 15% of strokes related to the territory of the carotid artery are associated with its complete occlusion. There is an important subgroup of patients with cerebrovascular occlusive diseases who might benefit from an external-carotid-to-internal-carotid bypass. In the present study, we report a case of a 53-year-old male patient with stenosis of the M2 branch of the middle cerebral artery (MCA), with a history of ∼ 20 episodes of transient ischemic accidents (TIA)s, in whom an anastomosis of the M4 branch of the superficial temporal artery-MCA was performed. The patient was discharged in three days, and in the two years of follow-up, they were no more TIAs. We also conducted a review of the literature on cerebrovascular occlusive disease and extracranial-intracranial bypass surgery. New methods to evaluate cerebral hemodynamics made it possible to classify a new subgroup of patients with symptomatic cerebrovascular disease and documented cerebrovascular compromise in whom the drug therapy fails, who can benefit from the extracranial-intracranial bypass. Our case report illustrates the advantages of revascularization in these selected patients.

Postpartum-Onset Moyamoya Disease: A Rare Cause of Stroke in Unexpected

Moyamoya disease (MMD) is a chronic cerebrovascular occlusive disease that is characterized by progressive bilateral stenosis of the terminal portion of the internal carotid artery and its main branches. Cerebrovascular events are the primary presenting symptoms and are related both to stenosis and occlusion of the ICAs and their main branches. Detection of bilateral stenosis by cerebral angiography is considered the gold standard, but computed tomography angiography (CTA) is also an acceptable method of diagnosis. In the current literature, there are no precise data on the incidence of moyamoya disease in Europe and the United States. Also, the pathogenesis of MMD remains obscure, and genetic factors and inflammation are the two most representative mechanisms. Here, we report the case of MMD in a 29-year-old African American female who presented with an ischemic stroke for the second time that manifested after pregnancy. This case is important to increase awareness of the probability of this rare disease in Western countries as well as to call attention to pregnancy’s accelerating effects of MMD. Careful, long-term neurologic and radiologic follow-up is essential in adult patients with MMD to prevent additional stroke events and improve outcomes.

Pedicled temporoparietal fascial flap for combined revascularization in adult moyamoya disease

Moyamoya disease (MMD) is a progressive, idiopathic cerebrovascular occlusive disease. Various revascularization techniques including direct, indirect, and combined microvascular bypasses have been described. This article presents a modified revascularization technique for MMD utilizing a pedicled temporoparietal fascial flap (TPFF) for combined revascularization. This technique combines a large area of coverage for indirect revascularization with the benefits of a direct bypass. The pedicled TPFF also benefits from intact venous drainage to minimize the risk of flap swelling that could result in complications from mass effect.

P3710Long term follow-up in a real-world study cohort after patent foramen ovale closure

Background Patent foramen ovale (PFO) closure is the treatment of choice after cryptogenic stroke according recent evidence. The indication is based on results of several randomized controlled trials; however, the results of these trials may not be extrapolated to a real-world clinical setting. Therefore, the aim of the present study was to evaluate long-term outcome regarding recurrent stroke, migraine, and/or peripheral embolism in patients after PFO closure. Methods We retrospectively analyzed outcomes of consecutive patients undergoing PFO closure from 2011 to 2018 at two interventional sites with respect to periprocedural events occurring during hospitalization and long-term follow-up. Follow-up data were collected from outpatient visits or telephone interviews. Results The analysis included 214 consecutive patients (mean age 52 years; 58% male). The follow-up rate was 96% and the mean follow-up time was 38 (SD 22) months. The index vascular event leading to PFO closure was stroke (n=190; 89%), including patients with repetitive stroke (n=36), embolic myocardial infarction (n=21), and migraine (n=3). One quarter (24.6%) of the population studied had an atrial septal aneurysm (>15 mm). Procedural success was achieved in 98%. There were no procedure-related strokes or deaths. Periprocedural complications occurred in 16 patients (7%): two cases of pericardial tamponade, seven complications at the access site mainly caused by bleeding, two cases of transient atrial fibrillation, and five other complications. The Amplatz Septal Occluder™ was used in two thirds (64.5%) of the cases and the Gore Cardioform™ device in one third (28.6%). Four (2%) patients died during follow-up. None of these patients experienced a recurrent stroke. Ten (5%) other patients experienced a recurrent stroke. Patients with recurrent stroke events were older than patients without recurrent stroke (mean 62.6 [SD 8.8] years vs. mean 52.2 [SD 13.8] years; p=0.015) and had a higher rate of preexisting cerebrovascular occlusive disease (5 [50%] vs. 10 [6%]; p<0.0001). There was no difference in risk for recurrent stroke between patients with one prior stroke and more than one stroke before PFO closure (p=0.71). Atrial fibrillation occurred in 6.6% of the patients during follow-up, but only one of these patients had recurrent stroke. No other anatomic and vascular risk factors or antithrombotic treatments were identified as being predictive of embolic events after closure. Conclusion In this real-world PFO closure cohort the recurrent stroke rate is low, although it is higher than reported in the recent randomized controlled trials. Recurrent strokes after PFO closure may reflect additional comorbid risk factors such as age or cerebrovascular occlusive disease that are unrelated to the potential for paradoxical embolism.

Surgery for Moyamoya Disease in Children

Moyamoya disease is a chronic progressive cerebrovascular occlusive disease of the terminal portion of the internal carotid arteries associated with an acquired abnormal vascular network at the base of the brain, often leading to ischemic or hemorrhagic stroke. Moyamoya disease is a relatively common cause of pediatric stroke with a specific racial and well-identified clinical and imaging phenotype. Moyamoya disease is more prevalent in East Asian countries compared with other geographic regions with a higher incidence of familial cases and clinically more aggressive form. Moyamoya disease is one of the few causes of stroke that is amenable to effective surgical revascularization treatment. There are various surgical options available for revascularization, including the direct, indirect, or combined bypass techniques, each with variable responses. However, due to the heterogeneity of the diseases, different clinical course, geographical variables associated with the disease, and availability of a wide variety of surgical revascularization procedures, optimal selection of a surgical candidate and the surgical technique becomes challenging, particularly in the pediatric population. This brief review presents pertinent literature of clinical options for the diagnosis and surgical treatment of moyamoya disease in children.