Effect of Pulsatility on the Transport of Thrombin in an Idealized Cerebral Aneurysm Geometry

Computational models of cerebral aneurysm thrombosis are designed for use in research and clinical applications. A steady flow assumption is applied in many of these models. To explore the accuracy of this assumption a pulsatile-flow thrombin-transport computational fluid dynamics (CFD) model, which uses a symmetrical idealized aneurysm geometry, was developed. First, a steady-flow computational model was developed and validated using data from an in vitro experiment, based on particle image velocimetry (PIV). The experimental data revealed an asymmetric flow pattern in the aneurysm. The validated computational model was subsequently altered to incorporate pulsatility, by applying a data-derived flow function at the inlet boundary. For both the steady and pulsatile computational models, a scalar function simulating thrombin generation was applied at the aneurysm wall. To determine the influence of pulsatility on thrombin transport, the outputs of the steady model were compared to the outputs of the pulsatile model. The comparison revealed that in the pulsatile case, an average of 10.2% less thrombin accumulates within the aneurysm than the steady case for any given time, due to periodic losses of a significant amount of thrombin-concentrated blood from the aneurysm into the parent vessel’s bloodstream. These findings demonstrate that pulsatility may change clotting outcomes in cerebral aneurysms.

Sex Differences in Cerebral Aneurysms and Subarachnoid Hemorrhage

Sex differences in cerebral aneurysm occurrence and characteristics have been well described. Although sex differences in outcomes following ischemic stroke have been identified, the effect of sex on outcomes following hemorrhagic stroke, and in particular, aneurysm treatment has been less studied. We describe the current state of knowledge regarding the impact of sex on treatment and outcomes of cerebral aneurysms. Although prior studies suggest that aneurysm prevalence and progression may be related to sex, we did not find clear evidence that outcomes following subarachnoid hemorrhage vary based on sex. Last, we identify areas for future research that could enhance understanding of the role sex plays in this context.

Flow Diverter Device for Treatment of Cerebral Aneurysm with Short-Term Follow Up: Two Case Reports

The flow diverter device (FDD) is an important treatment method for cerebral aneurysms, especially for intracranial dissecting aneurysms. This paper is the result of FDD treatment for two cases of vertebral dissecting aneurysm (VADA) patients and short-term follow-up at 3 months. All two cases were targeted for unruptured cerebral aneurysm, and 4-vessel angiography was performed as a follow-up examination for 3 months after receiving the procedure. As result, it was possible to shorten the period of use of antiplatelet drugs. In the case of VADA, there are limitations in general coiling procedures or conventional surgical treatment methods. In that sense, the FDD treatment method can be a very effective alternative treatment of VADA

The utility of dual-energy computed tomography angiography for the evaluation of brain aneurysms after endovascular coiling: a prospective study

Background Non-invasive alternatives to digital subtraction angiography (DSA) for follow-up of patients with coiled aneurysms are sought. Purpose To compare a novel method of dual-energy computed tomography angiography (DE-CTA) for postoperative assessment of coiled brain aneurysms to detect aneurysm recanalization and patency of adjacent blood vessels, with DSA. Material and Methods Patients who underwent endovascular cerebral aneurysm coiling were prospectively evaluated postoperatively by both DE-CTA and conventional DSA. CTA was performed using a novel dual-energy method with single-source and fast kilovoltage switching. DSA was performed using biplanar cerebral angiography. An experienced neuroradiologist and neurosurgeon, both blinded to the original radiological results, reviewed the images. Results A total of 54 patients (16 men, 38 women; mean age=47.6 + 9 years) with 55 coiled aneurysms were enrolled in our study between July 2014 and June 2015: 29 patients had suffered a subarachnoid hemorrhage and 26 patients had an incidentally found cerebral aneurysm. All patients had at least one DSA and DE-CTA performed at most one week apart. DE-CTA showed a 100% sensitivity and specificity in detection of complete aneurysm occlusion and 80% sensitivity and specificity for detection of residual necks and domes. DE-CTA successfully detected all vascular diameter changes as comparable to DSA with minimal interfering artifact. Conclusion DE-CTA is a promising non-invasive alternative to conventional catheter-based angiography for identification of aneurysm recurrence and assessment of adjacent arteries after endovascular coiling. It allows for far more rapid image acquisition than DSA, is non-invasive, and is widely available at clinical centers.

Adjuvant hyperbaric oxygen treatment of acute brain herniation after microsurgical clipping of a recurring cerebral aneurysm: a case report

Introduction: Acute brain herniation is a life-threatening neurological condition that occasionally develops due to severe complications following cerebral aneurysm clipping. Strategies for managing acute brain herniation have not improved substantially during the past decade. Hyperbaric oxygen treatment (HBOT) may alleviate harmful effects of cerebral hypoxia, which is one of the most important pathophysiological features of acute brain herniation and, therefore, may be useful as an adjuvant therapy for acute brain herniation. A case treated with adjuvant HBOT is reported. Case report: A 60-year-old asymptomatic man presented with a recurring left middle cerebral artery bifurcation aneurysm with previous stent-assisted embolisation. After craniotomy for surgical clipping of the aneurysm, disturbance of consciousness and right hemiplegia occurred. Computed tomography (CT) images suggested simultaneous cerebral ischaemia and intracranial haemorrhage. Pharmacologic treatment resulted in no improvement. A CT scan acquired five days after surgery showed uncal and falcine herniation. HBOT was administered five days after surgery, and the patient’s condition dramatically improved. He became conscious, and his hemiplegia improved following seven sessions of HBOT. Simultaneously, CT images showed regression of the acute brain herniation. Conclusions: The patient had recovered completely at one year post-treatment. HBOT may be effective in the treatment of acute brain herniation following cerebral aneurysm clipping.

Pituitary Adenomas Associated with Intracranial Aneurysms: the Clinical Characteristics, Therapeutic Strategies, and Possible Effects of Vascular Remodeling Factors

Background Pituitary adenoma coexists with intracranial aneurysms in 2.3 to 3.6% of cases, and intracranial aneurysms are thought to be incidental. On the other hand, older age and cavernous sinus invasion are reported to increase the rate of coexistence, so these two diseases may be related. Methods Ten males and 14 females with the coexistence of pituitary adenomas and intracranial aneurysms were retrospectively investigated among 923 patients (2.6%). Patients were subdivided into two groups: those with direct attachment of cerebral aneurysms to the pituitary adenomas and those without direct attachment. The clinical characteristics, therapeutic strategies, and possible effects of vascular remodeling factors were investigated. Results Twelve patients had functioning pituitary adenomas, and cavernous sinus invasion was identified in 7 of 24 patients. Five of these 7 patients were treated with priority for the cerebral aneurysm until 2007, whereas 14 of 17 patients without involvement of the aneurysm tip in the tumor were treated with priority for the pituitary adenoma in the later period. Among vascular remodeling factors, strong expression of vascular endothelial growth factor (VEGF) was significantly associated with the coexistence of pituitary adenoma and cerebral aneurysm (p < 0.05). Conclusion Intracranial aneurysms were found to coexist in 2.6% of cases of surgically treated pituitary adenomas. VEGF-induced arterial wall remodeling may be part of the mechanism of association between pituitary adenomas and cerebral aneurysms, suggesting possible causative mechanism.