Visuell evozierte Antworten der corticalen Areale V1/V2 und V5 nach Schachbrettmusterumkehrreizung - Magnetenzephalographische Untersuchungen in Kombination mit cytoarchitektonischen Wahrscheinlichkeiten

Ziel dieser Arbeit ist die präzise anatomische Identifikation der corticalen Quellen visuell evozierter magnetischer Felder (VEFs) bei Schachbrettmusterumkehrreizung und die Bestimmung der zugehörigen Zeitgänge. Durch visuelle Stimulation mit Schachbrettmusterumkehrreizung werden cerebrale Neuronenpopulationen aktiviert. Die Aktivierung cerebraler Neuronenpopulationen führt dazu, daß im Gehirn Ströme fließen. Diese Hirnströme produzieren Magnetfelder, welche als Korrelate der elektrischen Signalübertragung neuronaler Hirnzellen zu verstehen sind und mittels Magnetenzephalographie (MEG) nicht-invasiv außerhalb des Kopfes gemessen werden können ... Durch Verwendung geeigneter Rückrechnungsverfahren lassen sich die, den gemessenen Magnetfeldern zugrundeliegenden Ströme, im Gehirn lokalisieren. Das in der vorliegenden MEG-Studie angewandte Rückrechnungsverfahren Magnetfeld-Tomographie (MFT) ermöglicht es, den im Rahmen einer Reizantwort in jedem cerebralen Volumenelement (Voxel) aktivierten Strom zu bestimmen. [...

Coordinated reset neuromodulation for Parkinson's disease: proof-of-concept study.

The discovery of abnormal synchronization of neuronal activity in the basal ganglia in Parkinson's disease (PD) has prompted the development of novel neuromodulation paradigms. Coordinated reset neuromodulation intends to specifically counteract excessive synchronization and to induce cumulative unlearning of pathological synaptic connectivity and neuronal synchrony.In this prospective case series, six PD patients were evaluated before and after coordinated reset neuromodulation according to a standardized protocol that included both electrophysiological recordings and clinical assessments.Coordinated reset neuromodulation of the subthalamic nucleus (STN) applied to six PD patients in an externalized setting during three stimulation days induced a significant and cumulative reduction of beta band activity that correlated with a significant improvement of motor function.These results highlight the potential effects of coordinated reset neuromodulation of the STN in PD patients and encourage further development of this approach as an alternative to conventional high-frequency deep brain stimulation in PD

The Use of Flow Diverter in Ruptured, Dissecting Intracranial Aneurysms of the Posterior Circulation

OBJECTIVE: Acute dissecting aneurysms of the posterior circulation are a rare cause of subarachnoid hemorrhage. Established endovascular treatment options include parent artery occlusion and stent-assisted coiling, but appear to be associated with an increased risk of ischemic stroke. Vessel reconstruction with flow diverters is an alternative treatment option; however, its safety and efficacy in the acute stage remains unclear. METHODS: This is a multicentric retrospective analysis of 15 consecutive acutely ruptured dissecting posterior circulation aneurysms treated with flow diverters. The primary end point was favorable aneurysm occlusion, defined as OKM C1-3 and D (O'Kelly Marotta scale). Secondary end points were procedure-related complications and clinical outcome. RESULTS: Nine of 15 aneurysms (60%) arose from the intradural portion of the vertebral artery, 3 were located on the posterior inferior cerebellar artery and 1 each on the anterior inferior cerebellar artery, posterior cerebral artery, and basilar artery. Flow diverter placement was technically successful in 14 of 15 cases (93%). After endovascular treatment, none of the ruptured aneurysms rebled. Median clinical follow-up was 217 days and median angiographic follow-up was 203 days. Favorable occlusion was observed in 7 of 14 aneurysms (50%) directly after flow diverter placement; of those, 5 were completely occluded (36%). Seven patients (47%) with poor-grade subarachnoid hemorrhage died in the acute phase. Favorable clinical outcome (modified Rankin scale <= 2) was observed in 4 of 15 patients (27%) and a moderate outcome (modified Rankin scale 3/4) was observed in 5 of 15 patients (33%). All aneurysms showed complete occlusion at follow-up. CONCLUSIONS: Flow diverters might be a feasible, alternative treatment option for acutely ruptured dissecting posterior circulation aneurysms and may effectively prevent rebleeding. Larger cohort studies are required to validate these results

Mechanical Thrombectomy in Basilar Artery Occlusion: Presence of Bilateral Posterior Communicating Arteries is aPredictor of Favorable Clinical Outcome

BackgroundMechanical thrombectomy (MT) of basilar artery occlusions (BAO) is asubject of debate. We investigated the clinical outcome of MT in BAO and predictors of afavorable outcome.Material and MethodsA total of 104 MTs of BAO (carried out between 2010 and 2016) were analyzed. Favorable outcome as a modified Rankin scale (mRS) 2 at 90days was the primary endpoint. The influence of the following variables on outcome was investigated: number of detectable posterior communicating arteries (PcoAs), patency of basilar tip, completeness of BAO and posterior circulation Alberta Stroke Program early computed tomography score (PC-ASPECTS). Secondary endpoints were technical periprocedural parameters including symptomatic intracranial hemorrhage (sICH).ResultsThe favorable clinical outcome at 90days was 25% and mortality was 43%. The rate of successful reperfusion, i.e. modified thrombolysis in cerebral infarction (mTICI) 2b was 82%. Presence of bilateral PcoAs (area under the curve, AUC: 0.81, odds ratio, OR: 4.2, 2.2-8.2; p< 0.0001), lower National Institute of Health Stroke Scale (NIHSS) on admission (AUC: 0.74, OR: 2.6, 1.3-5.2; p< 0.01), PC-ASPECTS 9 (AUC: 0.72, OR: 4.2, 1.5-11.9; p< 0.01), incomplete BAO (AUC: 0.66, OR: 2.6, 1.4-4.8; p< 0.001), and basilar tip patency (AUC: 0.66, OR: 2.5, 1.3-4.8; p< 0.01) were associated with a favorable outcome. Stepwise logistic regression analysis revealed that the strongest predictors of favorable outcome at 90days were bilateral PcoAs, low NIHSS on admission, and incomplete BAO (AUC: 0.923, OR: 7.2, 3-17.3; p< 0.0001).ConclusionThe use of MT for BAO is safe with high rates of successful reperfusion. Aside from baseline NIHSS and incomplete vessel occlusion, both known predictors of favorable outcome in anterior circulation events, we found that collateral flow based on the presence or absence of PcoAs had adecisive prognostic impact

Incomplete Large Vessel Occlusions in Mechanical Thrombectomy: An Independent Predictor of Favorable Outcome in Ischemic Stroke

Background and Purpose: Cerebral large vessel occlusion (LVO) in acute ischemic stroke (AIS) may be complete (CLVO) or incomplete (ILVO). The influence of ILVO on clinical outcome after mechanical thrombectomy (MT) remains unclear. We investigated primarily the clinical outcome in patients with AIS due to ILVO or CLVO. Methods: Five hundred three consecutive AIS patients with LVO treated with stent-retriever or direct aspiration-based MT between 2010 and 2016 were analyzed. The primary endpoint was favorable clinical outcome (modified Rankin Scale <= 2) at 90 days; secondary endpoints were periprocedural parameters. Results: Forty-nine patients (11.3%) with a median National Institutes of Health Stroke Scale (NIHSS) of 11 presented with ILVO and the remainder presented with CLVO and median NIHSS of 15 (p < 0.001). The median groin puncture-to-reperfusion time was 30 vs. 67 min, respectively (p < 0.001). Successful reperfusion was reached in 47 out of 49 ILVO (95.9%) vs. 298 out of 381 CLVO (78.2%; p < 0.005) with less retrieval maneuvers (1.7 +/- 2.2 vs. 3.0 +/- 2.5; p < 0.001). The favorable outcome at 90 days was 81% in patients with ILVO vs. 29.1% in CLVO (p < 0.001); respective all-cause mortality rates were 6.4 vs. 28.5% (p < 0.001). Periprocedural complications (6.9%) occurred exclusively in CLVO patients (p < 0.05). ILVO was associated with favorable clinical outcome independent of age and NIHSS in multivariate logistic regression both in the anterior (OR 3.6; 95% CI 1.8-6.9; p < 0.001) and posterior circulation (OR 3.5; 95% CI 1.8-6.9; p < 0.001). Conclusions: AIS due to ILVO is frequent and is associated with a nearly threefold higher chance of favorable clinical outcome at 90 days, independent of age and initial NIHSS compared to CLVO. (C) 2017 S. Karger AG, Base

Order of Treatment Matters in Ischemic Stroke: Mechanical Thrombectomy First, Then Carotid Artery Stenting for Tandem Lesions of the Anterior Circulation

Background: One endovascular treatment option of acute ischemic stroke due to tandem occlusion (TO) comprises intracranial thrombectomy and acute extracranial carotid artery stenting (CAS). In this setting, the order of treatment may impact the clinical outcome in this stroke subtype. Methods: Retrospective analysis was performed on data prospectively collected in 4 international stroke centers between 2013 and 2017. One hundred sixty-five patients with anterior TO were treated by endovascular therapy. Clinical and procedural data were evaluated. Favorable clinical outcome was defined as modified Rankin Scale (mRS) = 2 at 90 days. Propensity score matching was performed for different treatment strategies. Results: Patients' mean age was 65 +/- 11 years and 118 were male (69%). The median admission National Institutes of Health Stroke Scale was 15 (interquartile range 8). In 59% of the patients (n = 101), the antegrade strategy (first stenting, then thrombectomy) was -performed, in 41% (n = 70) retrograde treatment (first thrombectomy, then stenting). Successful reperfusion (mTICI = 2b) was achieved in 128 patients (75%). Fifty-nine patients (39%) showed a favorable clinical outcome after 90 days. After propensity score matching, data of 100 patients could be analyzed. Analysis revealed that the retrograde strategy yielded a significantly higher rate of successful reperfusion compared to the antegrade strategy (92 vs. 56%; p < 0.001). The rate of favorable clinical outcome after 90 days (mRS = 2) was consistently higher (44 vs. 30%; p < 0.05) in the retrograde strategy group. Conclusion: Mechanical thrombectomy prior to acute CAS in TO is a predictive factor for favorable clinical outcome at 90 days. (c) 2018 S. Karger AG, Base

Carotid Artery Stenosis Contralateral to Acute Tandem Occlusion: An Independent Predictor of Poor Clinical Outcome after Mechanical Thrombectomy with Concomitant Carotid Artery Stenting

Background and Purpose: Cerebral ischemic strokes due to extra-/intracranial tandem occlusions (TO) of the anterior circulation are responsible for causing mechanical thrombectomy (MT). The impact of concomitant contralateral carotid stenosis (CCS) upon outcome remains unclear in this stroke subtype. Methods: Retrospective analysis of prospectively collected data of 4 international stroke centers between 2011 and 2017. One hundred ninety-seven consecutive patients with anterior TO were treated with MT and acute carotid artery stenting (CAS). Clinical (including demographics and National Institutes of Health Stroke Scale [NIHSS]), imaging (including angiographic evaluation of CCS) and procedural data were evaluated. Favorable clinical outcome was defined as modified Rankin Scale (mRS) 50% is an independent predictor of poor clinical outcome. This most likely cause is due to poorer collateral flow to the affected tissue. (c) 2017 S. Karger AG, Base