Koponyaűri aneurysmák hemodinamikai elemzése: vérzési kockázat és műtéti hatékonyság = Hemodynamic analysis of intracranial aneurysms: risk of bleeding and efficacy of treatment

Koponyaűri aneurysmák áramlástani elemzését végeztük idealizált 2D és 3D geometriai modelleken valamint valós aneurysmákról készült rotációs angiográfia 3D rekonstrukciójából készült véges elemes modelleken, számítógépes áramlás szimulációval. Idealizált modelleken összefüggést találtunk az aneurysma bemeneti nyílásának ("nyak") átmérője illetve területe és az aneurysmán belüli rotációs áramlás mértéke között. A nyak magassága befolyásolta a kialakuló örvényáramok helyét és számát. A legnagyobb nyíróerő a nyak áramlásirány szerinti távoli pontján lép fel. Valós aneurysmák véges elemes modelljein az áramlási mintát meghatározta, hogy az aneurysma a szülőér kanyarulatának küső vagy belső ívén, vagy elágazási pontján alakult-e ki, valamint hogy nyaka körkörösen, vagy csak egy oldalon érinti a szülőér falát. További különbséget eredményezett az aneurysma legnagyobb magassága és a szülőér hossztengelye által bezárt szög. Az érfalat falát körkörösen involváló zsákoknál szabálytalan örvényáramlást, a szülőérrel párhuzamosan elrendezett aneruysmáknál pedig sugár-áramlást észleltünk. Utóbbi esetekben az aneurysmzsák távoli fala áramlás elosztóként viselkedik. A dynamikus nyomás ilyenkor egyenetlen, az áramláselosztó pontnak megfelelően kisebb csúcsot mutat, míg más esetekben a zsák fala mentén egyenletes. Nem talátlunk egyértelmű összefüggést a nyíróerők eloszlásával kapcsolatban. Mindezek alapján megalapozottan feltehető, hogy a körkörös nyakkal eredő illetve a szülőér hossztengelyével párhuzamosan elrendezett aneurysmák hemodynamikai terhelése és vérzési kockázata magasabb lehet. | Peri-aneurysmal flow was studied in 2D and 3D idealized geometric models of sidewall aneurysms and on finite element models of real human intracranial aneurysms based on 3D reconstruction of rotational angiographic images using computerized flow simulations. On ideal models, the diameter and surface of the aneurysm?s entrance ("neck") significantly impacted the amount of rotational flow within the aneurysm sac and the heights of neck affected the number and site of intra-aneurysmal vortices. The peak shear stress was found at the upstream edge of the neck. On real aneurysm models, the flow pattern was influenced by the location of aneurysms on the inner or outer surface of a loop of the parent artery, by the limited or circumferential involvement of the parent artery?s wall and by the angle between the parent artery?s main axis and the heights of the aneurysm sac. Vortex flow was found in sidewall aneurysms with limited neck involvement, irregular vortex in those with circumferential involvement and jet flow in aneurysms with a parallel arrangement in relation to the parent artery. Dynamic pressure was unevenly distributed over the wall of the aneurysm in these later cases, while there was no peak of pressure in the others. No firm relationship was found between aneurysm geometry and shear stress distribution. These results suggest that aneurysms in a parallel position to the parent artery and those with circumferential involvement of the parent artery?s wall may have an increased hemodynamic stress and subsequently a higher likelihood of rupture

Multiple Coaxial Catheter System for Reliable Access in Interventional Stroke Therapy

In some patients with acute cerebral vessel occlusion, navigating mechanical thrombectomy systems is difficult due to tortuous anatomy of the aortic arch, carotid arteries, or vertebral arteries. Our purpose was to describe a multiple coaxial catheter system used for mechanical revascularization that helps navigation and manipulations in tortuous vessels. A triple or quadruple coaxial catheter system was built in 28 consecutive cases presenting with acute ischemic stroke. All cases were treated by mechanical thrombectomy with the Penumbra System. In cases of unsuccessful thrombo-aspiration, additional thrombolysis or angioplasty with stent placement was used for improving recanalization. The catheter system consisted of an outermost 8-Fr and an intermediate 6-Fr guiding catheter, containing the inner Penumbra reperfusion catheters. The largest, 4.1-Fr, reperfusion catheter was navigated over a Prowler Select Plus microcatheter. The catheter system provided access to reach the cerebral lesions and provided stability for the mechanically demanding manipulations of thromboaspiration and stent navigation in all cases. Apart from their mechanical role, the specific parts of the system could also provide access to different types of interventions, like carotid stenting through the 8-Fr guiding catheter and intracranial stenting and thrombolysis through the Prowler Select Plus microcatheter. In this series, there were no complications related to the catheter system. In conclusion, building up a triple or quadruple coaxial system proved to be safe and efficient in our experience for the mechanical thrombectomy treatment of acute ischemic strok

Use of the Enterprise™ Intracranial Stent for Revascularization of Large Vessel Occlusions in Acute Stroke

Background and Purpose:: Major cerebral thromboembolism often resists recanalization with currently available techniques. The authors present their initial experience with a self-expanding stent for use in intracranial vascular reconstruction, permitting immediate recanalization of acute thromboembolic occlusions of the anterior circulation. Patients and Methods:: Patients treated with the Cordis Enterprise™ self-expanding intracranial stent system for acute thromboembolic occlusion of the major anterior cerebral arteries were included. Treatment comprised systemic and intraarterial thrombolysis, mechanical thrombectomy, and stent placement. Stent deployment, recanalization rate by means of Thrombolysis In Cerebral Infarction (TICI) scores and the clinical outcome were all assessed. Results:: Six patients presenting with acute carotid T (n = 2) or proximal middle cerebral artery occlusion (n = 4) were treated. The mean National Institutes of Health Stroke Scale (NIHSS) score at presentation was 14; the mean age was 57 years. Successful stent deployment and immediate recanalization were achieved in all six with a TICI score of ≥ 2. Neither distal emboli nor any procedure-related complications were encountered. One patient developed symptomatic intracerebral hemorrhage and two patients needed decompressive craniectomy after treatment. The mean NIHSS score at 10 days was 10, but only one patient showed a complete recovery at 3 months. Conclusion:: Intracranial placement of the Enterprise™ self-expanding stent has proven to be feasible and efficient in achieving immediate recanalization of occluded main cerebral arteries. The use of antiplatelet therapy after treatment may, however, increase the risk of reperfusion intracerebral hemorrhag

Dual-Energy Computed Tomography in Stroke Imaging : Value of a New Image Acquisition Technique for Ischemia Detection after Mechanical Thrombectomy

OBJECTIVE: To assess if a new dual-energy computed tomography (DECT) technique enables an improved visualization of ischemic brain tissue after mechanical thrombectomy in acute stroke patients. MATERIAL AND METHODS: The DECT head scans with a new sequential technique (TwinSpiral DECT) were performed in 41 patients with ischemic stroke after endovascular thrombectomy and were retrospectively included. Standard mixed and virtual non-contrast (VNC) images were reconstructed. Infarct visibility and image noise were assessed qualitatively by two readers using a 4-point Likert scale. Quantitative Hounsfield units (HU) were used to assess density differences of ischemic brain tissue versus healthy tissue on the non-affected contralateral hemisphere. RESULTS: Infarct visibility was significantly better in VNC compared to mixed images for both readers R1 (VNC: median 1 (range 1-3), mixed: median 2 (range 1-4), p < 0.05) and R2 (VNC: median 2 (range 1-3), mixed: 2 (range 1-4), p < 0.05). Qualitative image noise was significantly higher in VNC compared to mixed images for both readers R1 (VNC: median 3, mixed: 2) and R2 (VNC: median 2, mixed: 1, p < 0.05, each). Mean HU were significantly different between the infarcted tissue and the reference healthy brain tissue on the contralateral hemisphere in VNC (infarct 24 ± 3) and mixed images (infarct 33 ± 5, p < 0.05, each). The mean HU difference between ischemia and reference in VNC images (mean 8 ± 3) was significantly higher (p < 0.05) compared to the mean HU difference in mixed images (mean 5 ± 4). CONCLUSION: TwinSpiral DECT allows an improved qualitative and quantitative visualization of ischemic brain tissue in ischemic stroke patients after endovascular treatment

Prognostic assessment in patients operated for brain metastasis from systemic tumors

Background: Established models for prognostic assessment in patients with brain metastasis do not stratify for prior surgery. Here we tested the prognostic accuracy of the Graded Prognostic Assessment (GPA) score model in patients operated for BM and explored further prognostic factors. Methods: We included 285 patients operated for brain metastasis at the University Hospital Zurich in the analysis. Information on patient characteristics, imaging, staging, peri- and postoperative complications and survival were extracted from the files and integrated into a multivariate Cox hazard model. Results: The GPA score showed an association with outcome. We further identified residual tumor after surgery (p = 0.007, hazard ratio (HR) 1.6, 95% confidence interval (CI) 1.1-2.3) steroid use (p = 0.021, HR 1.7, 95% CI 1.1-2.6) and number of extracranial metastasis sites (p = 0.009, HR 1.4, 95% CI 1.1-1.6) at the time of surgery as independent prognostic factors. A trend was observed for postoperative infection of the subarachnoid space (p = 0.102, HR 3.5, 95% CI 0.8-15.7). Conclusions: We confirm the prognostic capacity of the GPA score in a cohort of operated patients with brain metastasis. However, extent of resection and steroid use provide additional aid for the prognostic assessment in these patients

Subsequent effect of subacute T-2 toxicosis on spermatozoa, seminal plasma and testosterone production in rabbits

Pannon White (n512) male rabbits (weight: 4050 to 4500 g, age: 9 months) received 2ml of a suspension containing purified T-2 toxin by gavage for 3 days. The daily toxin intake was 4 mg/animal (0.78 to 0.99 mg/kg body weight (BW)). Control animals (n512) received toxin-free suspension for 3 days. Since a feed-refusal effect was observed on the second day after T-2 administration, a group of bucks (n510) were kept as controls (no toxin treatment) but on a restricted feeding schedule, that is, the same amount of feed was provided to them as was consumed by the exposed animals. On day 51 of the experiment (i.e. 48 days after the 3-day toxin treatment), semen was collected, and pH, concentration, motility and morphology of the spermatozoa, as well as concentration of citric acid, zinc and fructose in the seminal plasma, were measured. After gonadotropinreleasing hormone (GnRH) analogue treatment, the testosterone level was examined. One day of T-2 toxin treatment dramatically decreased voluntary feed intake (by 27% compared to control, P,0.05) and remained lower ( P,0.05) during the first 2 weeks after the withdrawal of the toxin. BW of the contaminated rabbits decreased by 88% on days 17 and 29 compared to controls ( P,0.05). No effect of toxin treatment was detected on pH and quantity of the semen or concentration of spermatozoa. The ratio of spermatozoa showing progressive forward motility decreased from 65% to 53% in the semen samples of toxin-treated animals compared to controls ( P.0.05). The ratio of spermatozoa with abnormal morphology increased ( P,0.05) in the ejaculates collected from the toxin-treated animals. T-2 toxin applied in high doses decreased the concentration of citric acid in seminal plasma ( P,0.05). No effect of T-2 toxin on the concentrations of the other seminal plasma parameters (fructose and zinc) was observed. T-2 toxin decreased the basic testosterone level by 45% compared to control ( P,0.01) and resulted in lower ( P,0.05) GnRH-induced testosterone concentration. Feed restriction, that is, less nutrient intake, resulted in more morphologically abnormal spermatozoa in the semen, but it did not cause significant loss in BW, motility of the spermatozoa, composition of the seminal plasma or testosterone concentration – its effect needs further examination

Flow-augmentation STA-MCA bypass for acute and subacute ischemic stroke due to internal carotid artery occlusion and the role of advanced neuroimaging with hemodynamic and flow-measurement in the decision-making: preliminary data

Symptomatic patients with ischemic stroke due to internal carotid artery (ICA) occlusion often present with compromised brain hemodynamic status involving substantially larger parts of the affected vascular territory than the ischemic core itself (1-3). Despite the fact that the “Extracranial-Intracranial” (EC-IC) Bypass Study Group and the “Carotid Occlusion Surgery Study” (COSS) failed to demonstrate a benefit of bypass in comparison to medical therapy (4,5), several studies showed a significant improvement in hemodynamic parameters after superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery was performed in carefully selected patients (6-9) and even a reduction in stroke recurrence (6). Analysis showed that the failure of the COSS trial (5) to show a benefit regarding ipsilateral 2-year stroke recurrence in patients undergoing cerebral bypass revascularization was likely caused by a failure of the semiquantitative, hemispheric oxygen extraction fraction (OEF) ratio method used in the trial than by the selection of the patients for bypass based on hemodynamic compromise (10). Therefore, alternative and especially quantitative imaging techniques are needed to assess hemodynamic status in patients with ischemic stroke due to ICA occlusion

Flow diversion treatment: intra-aneurismal blood flow velocity and WSS reduction are parameters to predict aneurysm thrombosis

Background: To evaluate the haemodynamic changes induced by flow diversion treatment in cerebral aneurysms, resulting in thrombosis or persisting aneurysm patency over time. Method: Eight patients with aneurysms at the para-ophthalmic segment of the internal carotid artery were treated by flow diversion only. The clinical follow-up ranged between 6days and 12months. Computational fluid dynamics (CFD) analysis of pre- and post-treatment conditions was performed in all cases. True geometric models of the flow diverter were created and placed over the neck of the aneurysms by using a virtual stent-deployment technique, and the device was simulated as a true physical barrier. Pre- and post-treatment haemodynamics were compared, including mean and maximal velocities, wall-shear stress (WSS) and intra-aneurysmal flow patterns. The CFD study results were then correlated to angiographic follow-up studies. Results: Mean intra-aneurysmal flow velocities and WSS were significantly reduced in all aneurysms. Changes in flow patterns were recorded in only one case. Seven of eight aneurysms showed complete occlusion during the follow-up. One aneurysm remaining patent after 1year showed no change in flow patterns. One aneurysm rupturing 5days after treatment showed also no change in flow pattern, and no change in the maximal inflow velocity. Conclusions: Relative flow velocity and WSS reduction in and of itself may result in aneurysm thrombosis in the majority of cases. Flow reductions under aneurysm-specific thresholds may, however, be the reason why some aneurysms remain completely or partially patent after flow diversio

Perkután csontcementes csigolyaplasztika hatása a szomszédos csigolyatestekre: elõzetes biomechanikai vizsgálat

In this preliminary study the authors have evaluated the biomechanical effect of two differentpercutaneous vertebral augmentation techniques – vertebroplasty and kyphoplasty – on adjacentvertebral bodies. The in vitro study was performed by applying compressive load on functionalspinal units containing three vertebrae. The middle vertebral body was previously treatedwith one of the above mentioned techniques. The results showed that the applied technologyis feasible for performing a larger sample size study to compare vertebroplasty andkyphoplasty in terms of their biomechanical effects on adjacent vertebrae.Az elõzetes biomechanikai vizsgálatban a szerzõk az osteoporosis talaján kialakult kompreszszióscsigolyatörések kezelésében alkalmazott perkután csigolyastabilizációs módszerek, avertebroplasztika és kyphoplasztika szomszédos csigolyatestekre gyakorolt hatásait vizsgálták.A vizsgálatot három csigolyatestet tartalmazó funkcionális gerincegységek végezték nyomóterhelésalkalmazásával. A funkcionális gerincegységek középsõ csigolyáját elõzetesen vertebroplasztikávalvagy kyphoplasztikával kezelték. Az eredmények azt mutatják, hogy a kidolgozottmódszer alkalmas egy nagyobb mintaszámú összehasonlító vizsgálat elvégzésére, amely választadhat arra a kérdésre, hogy a két perkután csigolyastabilizációs módszer szomszédos csigolyákragyakorolt biomechanikai hatásában van-e különbség. DOI: 10.17489/biohun/2009/2/0