Hemodynamic Differences Between Basilar Artery Fenestration and Normal Vertebrobasilar Artery: A Pilot Study

Background: Basilar artery fenestration has been proposed as a contributor to ischemic stroke, as unique flow patterns induced by fenestration may be related to thrombus formation or insufficiency. This study aimed to evaluate the hemodynamics of basilar artery fenestration (BAF) using computational fluid dynamics (CFD).Methods: Patients with BAF and normal vertebrobasilar system were recruited and separately evaluated using CFD. Specific geometric vascular models were reconstructed based on 3D-rotational angiography (3D-RA). Patients were divided into the BAF group and control group (i.e., patients with the normal vertebrobasilar system). Hemodynamic and geometric variables were calculated and compared between groups using Student's t-test or Wilcoxon rank-sum test.Results: Overall, 24 patients were included, with 12 patients each in the BAF group and the control group. The BAF group had a significantly smaller basilar artery diameter than the control group (3.1 ± 0.51 vs. 3.76 ± 0.4, p = 0.002). Compared to the control group, the BAF group had higher values of maxOSI (median, 0.3 vs. 0.09, p = 0.028), TAWSSG (median, 983.42 vs. 565.39, p = 0.038) in the flow confluence, higher SAR-TAWSSG in bifurcation (median, 70.22 vs. 27.65, p = 0.002) and higher SAR-TAWSSG in basilar artery (median, 48.75 vs. 16.17, p < 0.001) of the vertebrobasilar artery.Conclusions: This pilot study suggested that hemodynamic differences between BAF and normal vertebrobasilar artery across multiple shear flow parameters. The disturbed flow in the BAF may increase the risk of thrombus formation, plaque instability, and subsequent ischemic cerebrovascular events. These should be confirmed by future studies.

Cerebrovascular Anatomy and Pathophysiology

The cerebrospinal vasculature originates at the aortic arch. The right brachiocephalic artery divides into the right common carotid artery and the right subclavian artery. The left common carotid and left subclavian arteries arise directly from the aortic arch. The 2 common carotid arteries bifurcate into the internal and external carotid arteries. The anterior circulation of the brain includes the distal branches from the internal carotid artery, including the anterior cerebral artery and the middle cerebral artery. The vertebral arteries arise from the subclavians and join at the pontomedullary junction, forming the basilar artery. The vertebrobasilar system and distal branches are commonly known as the posterior circulation of the brain.

Regulation of Blood Flow in the Cerebral Posterior Circulation by Parasympathetic Nerve Fibers: Physiological Background and Possible Clinical Implications in Patients With Vertebrobasilar Stroke

Posterior circulation involves the vertebrobasilar arteries, which supply oxygen and glucose to vital human brainstem structures and other areas. This complex circulatory- perfusion system is not homogenous throughout the day; rather, its hemodynamic changes rely on physiological demands, ensuring brainstem perfusion. This dynamic autoregulatory pattern maintains cerebral perfusion during blood pressure changes. Accumulative evidence suggests that activity within the autonomic nervous system is involved in the regulation of cerebral blood flow. Neither the sympathetic nor parasympathetic nervous systems work independently. Functional studies have shown a tight and complicated cross talk between these systems. In pathological processes where sympathetic stimulation is present, systemic vasoconstriction is followed, representing the most important CNS parasympathetic trigger that will promote local vasodilation. Stroke is a clear example of this process. The posterior circulation is affected in 30% of strokes, causing high morbidity and mortality outcomes. Currently, the management of ischemic stroke is focused on thrombolytic treatment and endovascular thrombectomy within an overall tight 4.5 to 6 h ischemic time window. Therefore, the autonomic nervous system could represent a potential therapeutic target to modulate reperfusion after cerebral ischemia through vasodilation, which could potentially decrease infarct size and increase the thrombolytic therapeutic ischemic window. In addition, shifting the autonomic nervous system balance toward its parasympathetic branch has shown to enhance neurogenesis and decrease local inflammation. Regretfully, the vast majority of animal models and human research on neuromodulation during brain ischemia have been focused on anterior circulation with disappointing results. In addition, the source of parasympathetic inputs in the vertebrobasilar system in humans is poorly understood, substantiating a gap and controversy in this area. Here, we reviewed current available literature regarding the parasympathetic vascular function and challenges of its stimulation in the vertebrobasilar system.

The potential of duplex scanning in the diagnosis of pathological tortuosity of the vertebral artery

Aim. To assess the capabilities of duplex scanning and study the features of hemodynamics in the vertebral arteries before and after surgical treatment.Material and methods. The results of anatomical and circulatory characteristics of an extracranial segment of the vertebral arteries in 52 patients with various forms of pathological tortuosity were analyzed. Kinking was present in 38 patients, coiling in 8 patients, and Powers anomaly in 6 patients. There were 18 men and 34 women. The mean age of the patients was 45.6±8.7 years.Results and discussion. In all types of PT of VA with ostium stenosis, the diameter of the artery was decreased, and based on tortuosity it contributed both to the reduction and deterioration of arterial blood flow to the vertebrobasilar basin. The decrease or increase in the linear velocity of blood flow, as well as other blood flow parameters, depended on both the type of pathological tortuosity of the PA and on the vessel diameter and the value of angulation. Hypoplasia of the opposite vertebral artery also occurred in 28 patients, which resulted in impaired blood supply to the brain.Vascular examination after reconstructive surgeries resulted in normalization of the parameters of arterial circulation and cerebral perfusion. Primary vascular patency was 96.2%, restenosis was not revealed in any observation.Conclusion. Duplex scanning is a highly informative technique for both diagnosing pathological deformities of the vertebral arteries and assessing the restoration of the hemodynamics of the vertebrobasilar system after reconstructive surgery. This method provides the most accurate information on the anatomical form and localization of pathological deformities of the vertebral artery. It also allows quantitative assessment of cerebral blood flow.

Medicolegal evaluation of pontine hemorrhage at autopsy- Highlights from a case and an overview

One in ten non-traumatic intracerebral hemorrhages (ICH) is located in the pons with chronic arterial hypertension as the leading etiology. In the forensic context, deaths related to a pontine hemorrhage (PH) are usually encountered in situations of drug abuse, excited delirium, trauma, as well as in sudden natural deaths where some hypertensive catastrophe is the usual underlying mechanism. The clinical presentation of PH may be variable, causing a failure in timely diagnosis that, if presents with unexplainable circumstances, may become the subject of medicolegal concern. The present case relates to a middle-aged man with a long history of hypertension and presents during an afternoon with an abrupt onset of deleterious symptoms. The patient was managed conservatively but succumbed to his illness and expires during treatment. A questionable diagnosis and the case circumstances, however, directed the doctors to inform the police. A medicolegal autopsy was therefore carried out that leads to the discovery of a lethal pontine hemorrhage rupturing into the fourth ventricle and involving the adjacent cerebellar tissues as well. Severe atherosclerosis of the basal arteries constituting Circle of Willis and Vertebrobasilar system was seen along with their hallmark effects that became evident during brain sectioning. Pathological stigmata of well established hypertension were found in the heart and kidneys. A clinic pathological correlation of the physical characteristics and topography of the hematoma to its severity was also carried out, based upon the known CT and autopsy findings. The possibility of a drug related or traumatic and secondary brainstem/Duret hemorrhage was ruled out.

Vestibular vertigo in emergency neurology

The review deals with approaches to the differential diagnosis of the causes of vertigo in emergency neurology. The main causes of episodic and acute vestibular syndrome are discussed. Clinical diagnostic methods for acute vestibular syndrome (evaluation of nystagmus, test of skew, head-impulse test and neurological status) are considered. Clinical signs of “benign” acute vestibular syndrome and symptoms indicating a stroke in the vertebrobasilar system are presented. Differential diagnostic criteria for peripheral and central vestibular disorders are presented. Transient ischemic attacks, features of the otoneurologic status in vestibular neuronitis and different localizations of cerebral infarction focus are considered. Errors in the diagnosis of the vertigo causes are discussed.

Our Experience in the Treatment of Vertebrobasilar Insufficiency Due to Cervical Spine Disorders

This article defines vertebra-related causes of vertebrobasilar insufficiency in patients with the signs of tortuosity of segment VI of the VA. The aim of this study is to present the results of diagnostics of discirculatory phenomena in the vertebrobasilar system and to show their importance for differentiated surgical treatment of stenotic lesions of segment V1 of VA in pathological disorders of cerebral circulation in the VBS caused by osteochondrosis of the cervical spine. The following traditional methods are used in diagnostics: Doppler ultrasonography, multispiral computed tomography with contrast enhancement. Also using developed by the author method for determining VA reactivity and circulatory insufficiency in the vertebrobasilar system (VBS). Based on our methodology and criteria, patients were selected for different types of surgical treatment with clinical outcome prediction following interventions on the arteries of the VBS. To determine the pathologies of the intracranial segments of the vertebral and basilar arteries, taking into account the pathways of collateral compensation in the VBS, cerebral angiography is recommended before surgery on the arteries of the VBS. Reconstructive techniques used on segment VI of the VA will predictably show the best long-term clinical results. The excision of a tortuous segment VI of the VA may be effective in obtaining reliable results of successful interventions in the early postoperative period. The conservative treatment of the patients with multiple VBD lesions is possible. early outcomes of their use are satisfactory.

Intracranial Fusiform and Circumferential Aneurysms of the Main Trunk: Therapeutic Dilemmas and Prospects

Intracranial fusiform and circumferential aneurysms (IFCAs), especially those located on the main trunk, are uncommon and difficult to manage. Currently, literature focused on IFCAs on the main trunk of cerebral arteries is lacking. The treatment of IFCAs is still under debate. Therefore, in this review, we further explore the treatment of this complicated entity. In addition, we also present some interesting cases. Based on the literature review and our experience, we found that IFCAs are often located in the vertebrobasilar system and that ruptured or large symptomatic IFCAs are associated with increased mortality and higher rebleeding rates. The treatment strategies for IFCAs can be classified as deconstructive and reconstructive methods via open surgery and/or endovascular treatment (EVT). Currently, EVT is a popular method and the main therapeutic choice. In particular, flow diversion has revolutionized the treatment of IFCAs. Parent artery occlusion (PAO) with or without revascularization may still be considered a suitable choice. Complex IFCAs that cannot be resolved by EVT can also be treated via open surgery with or without extracranial–intracranial bypass. Targeted embolization for the weak points of IFCAs is a temporary or palliative choice that is rarely used. In summary, despite complications, both surgical treatment and EVT are effective options for appropriately selected cases. Due to the development of endovascular implants, EVT will have better prospects in the future.