Functional Outcomes at 90 Days in Octogenarians Undergoing Thrombectomy for Acute Ischemic Stroke: A Prospective Cohort Study and Meta-Analysis

Background: Elderly patients account for 30% of acute ischemic stroke (AIS) but are under-represented in randomized controlled trials of endovascular thrombectomy (EVT). Meta-analysis of “real world” studies evaluating 90-day outcomes in elderly patients ≥80 years have been limited to small numbers undergoing EVT with older generation devices.Methods: A retrospective analysis of 181 prospectively collected patients who received EVT for anterior circulation AIS at an Australian center over 2.5-years. The study aims to determine (i) 90-day functional outcomes (modified Rankin Scale mRS 0–2) in patients ≥80 vs. <80 years, (ii) the interaction of prognostic factors and age and (iii) compare our data to those previously reported using a meta-analysis of outcomes in observational studies using second generation thrombectomy devices.Results: We analyzed 2,387 patients (≥80 years, n = 649; <80 years, n = 1,738) from 14 studies including our study (≥80 years, n = 71; <80 years, n = 110). Twenty-eight percent of our and 30% of the meta-analysis elderly cohort achieved good 90-day mRS compared to 55 and 52%, respectively of younger patients (p < 0.001). Twenty-seven percent of our and 26% of the meta-analysis elderly cohort died compared to 16% (p = 0.07) and 15% (p < 0.0001), respectively of younger patients. Baseline NIHSS≥16 correlated with poor prognosis in elderly (OR 16.4; 95% CI 4.49–59.91, p < 0.001) and younger (OR 8.73;95% CI 3.35–22.80, p < 0.001) patients. Prior rt-PA was associated with favorable outcome in younger (OR 2.90; 95%CI 1.29–6.52, p = 0.01) patients only.Conclusion: EVT has less favorable outcomes in elderly patients. However, results are better than outcomes in historical controls not treated with thrombectomy providing further support for EVT in the elderly

Impact of interhospital transfer on patients undergoing endovascular thrombectomy for acute ischaemic stroke in an Australian setting

Objective To assess the impact of interhospital transfer on the interplay between functional outcome, mortality, reperfusion rates and workflow time metrics in patients undergoing endovascular thrombectomy (EVT) for acute ischaemic stroke due to large vessel occlusion (LVO) in the anterior cerebral circulation. Design, setting and participants This is an analysis of a prospective database of consecutive patients undergoing EVT for LVO presenting between January 2017 and December 2018 at a single Australian comprehensive stroke centre (CSC). Patients presented directly or were transferred to the CSC from 21 sites across New South Wales and the Australian Capital Territory. Main outcome measures The main outcome measures were rate of good 90-day functional outcome (modified Rankin Scale 0–2), successful reperfusion (Thrombolysis in Cerebral Infarction scale grade 2b or 3), symptomatic intracerebral haemorrhage (sICH) and 90-day mortality. Key workflow time metric milestones were examined. Results 154 of 213 (72%) patients were interhospital transfers. There was no significant difference in baseline characteristics including age, National Institutes of Health Stroke Scale score, intravenous thrombolysis administration or procedure time between transferred and direct presenters (all p>0.05). Transferred patients had worse 90-day functional outcome (39.6% vs 61.0%, OR 0.42, 95% CI 0.23 to 0.78), higher mortality (25.3% vs 6.8%, OR 4.66, CI 1.59 to 13.70) and longer stroke onset to treatment (groin puncture) time (298 min vs 205 min, p<0.01). Successful reperfusion rates and sICH were similar between the cohorts (96.8% vs 98.3%, and 7.8% vs 3.4%). Conclusion Interhospital transfer is associated with longer stroke onset to treatment, worse 90-day functional outcome and higher mortality compared with patients presenting directly to the CSC

Rescue therapy after failed thrombectomy in medium/distal vessel occlusions: a retrospective analysis of an international, multi-center registry

Background: There are limited therapeutic options in cases of failed reperfusion (modified thrombolysis in cerebral infarction [mTICI] score < 2b) after stent-retriever and/or aspiration based endovascular treatment (EVT) for acute ischemic stroke. Despite the absence of data supporting its use, rescue therapy (balloon angioplasty and/or stent implantation) is often utilized in such cases. Studies are limited to large vessel occlusions, while the outcomes and complications after rescue therapy in medium/distal vessel occlusions (MDVOs) have not been reported. This study aims to report the outcomes of rescue therapy in MDVO stroke patients. Methods: We performed an analysis of the "Blood pressure and Antiplatelet medication management after reScue angioplasty after failed Endovascular treatment in Large and distal vessel occlusions with probable IntraCranial Atherosclerotic Disease" (BASEL ICAD) retrospective registry. All MDVO stroke patients were included in the analysis. Results: Out of the 718 registry patients, 87 (12.1%) presented with an MDVO. Fifty-six patients (64.4%) showed an occlusion of the M2 segment of the middle cerebral artery. Rescue stenting was performed in 78 patients (89.7%) while balloon angioplasty alone was performed in 9 patients (10.3%). Successful reperfusion (mTICI score ⩾ 2b) was achieved in 73 (83.9%) patients after rescue therapy. Symptomatic intracranial hemorrhage (sICH) occurred in 8 patients (9.2%) and post-treatment stent occlusion in 12 patients (13.8%). Ninety days mortality was 20.7%. Twenty-eight patients (32.2%) achieved functional independence at 90 days (modified Rankin Scale 0-2). Conclusion: Rescue therapy with stenting and/or balloon angioplasty in patients undergoing EVT for isolated MDVO with suspected underlying intracranial atherosclerotic disease is an effective reperfusion strategy but is associated with complications and poor functional outcomes

Line orientation adaptation: local or global?

Prolonged exposure to an oriented line shifts the perceived orientation of a subsequently observed line in the opposite direction, a phenomenon known as the tilt aftereffect (TAE). Here we consider whether the TAE for line stimuli is mediated by a mechanism that integrates the local parts of the line into a single global entity prior to the site of adaptation, or the result of the sum of local TAEs acting separately on the parts of the line. To test between these two alternatives we used the fact the TAE transfers almost completely across luminance contrast polarity [1]. We measured the TAE using adaptor and test lines that (1) either alternated in luminance polarity or were of a single polarity, and (2) either alternated in local orientation or were of a single orientation. We reasoned that if the TAE was agnostic to luminance polarity and was parts-based, we should obtain large TAEs using alternating-polarity adaptors with single-polarity tests. However we found that (i) TAEs using one-alternating-polarity adaptors with all-white tests were relatively small, increased slightly for two-alternating-polarity adaptors, and were largest with all-white or all-black adaptors. (ii) however TAEs were relatively large when the test was one-alternating polarity, irrespective of the adaptor type. (iii) The results with orientation closely mirrored those obtained with polarity with the difference that the TAE transfer across orthogonal orientations was weak. Taken together, our results demonstrate that the TAE for lines is mediated by a global shape mechanism that integrates the parts of lines into whole prior to the site of orientation adaptation. The asymmetry in the magnitude of TAE depending on whether the alternating-polarity lines was the adaptor or test can be explained by an imbalance in the population of neurons sensitive to 1st-and 2nd-order lines, with the 2nd-order lines being encoded by a subset of the mechanisms sensitive to 1st-order lines

Management of spinal dural arteriovenous fistula in a child with myelopathy

Background: Spinal dural arteriovenous fistulas (DAVF) are rare intradural spinal lesions. Patients with DAVF are typically in the 40’s or 50’s, and classically present with acute neurological deterioration. Notably, these lesions are exceedingly rare in the pediatric age group. Case Description: A 2-year-old child presented with the sudden onset of lethargy, and 4/5 weakness of the left lower extremity with accompanying ataxia. The cervicothoracic MR scan revealed central cord edema from C5 to T4. A DAVF was diagnosed based on the multiple dilated intradural perimedullary veins. Following endovascular treatment, the child markedly recovered and remained stable 2 years later. Conclusion: DAVFs are treatable lesions that rarely occur in the pediatric age group. They are associated with serious neurological morbidity. When suspected, they should be immediately diagnosed with magnetic resonance imaging/magnetic resonance angiography, and formal angiography. Prompt neurosurgical and neuroradiological/ endovascular opinions and intervention should be sought to provide and the best treatment strategy. </jats:sec

Altering brain dynamics with transcranial random noise stimulation

AbstractRandom noise can enhance the detectability of weak signals in nonlinear threshold systems, a phenomenon known as stochastic resonance (SR). This concept is not only applicable to single threshold systems but can also be applied to dynamical systems with multiple attractor states, such as observed during the phenomenon of binocular rivalry. Binocular rivalry can be characterized by marginally stable attractor states between which the brain switches in a spontaneous, stochastic manner. The switches are thought to be driven by a combination of neuronal adaptation and noise. Here we used a computational model to predict the effect of noise on perceptual dominance durations when either low-contrast or high-contrast stimuli are presented. Subsequently we compared the model prediction to a series of three experiments where we measured binocular rivalry dynamics when noise (zero-mean Gaussian white noise) was added either to the visual stimulus (Exp. 1) or directly to the visual cortex (Exp. 2 and Exp. 3) by applying transcranial Random Noise Stimulation (tRNS 1mA, 100-640 Hz zero mean Gaussian white noise). We found that adding noise significantly reduced the mixed percept duration (Exp. 1 and Exp. 2). This effect was only present for low-contrast but not for high-contrast visual stimuli which is in line with the model predictions. Our results demonstrate that both central and peripheral noise can influence state-switching dynamics of binocular rivalry under specific conditions (e.g. low visual contrast stimuli), in line with a SR-mechanism.</jats:p

Altering brain dynamics with transcranial random noise stimulation

Random noise can enhance the detectability of weak signals in nonlinear systems, a phenomenon known as stochastic resonance (SR). This concept is not only applicable to single threshold systems but can also be applied to dynamical systems with multiple attractor states, such as observed during the phenomenon of binocular rivalry. Binocular rivalry can be characterized by marginally stable attractor states between which the brain switches in a spontaneous, stochastic manner. Here we used a computational model to predict the effect of noise on perceptual dominance durations. Subsequently we compared the model prediction to a series of experiments where we measured binocular rivalry dynamics when noise (zero-mean Gaussian random noise) was added either to the visual stimulus (Exp. 1) or directly to the visual cortex (Exp. 2) by applying transcranial Random Noise Stimulation (tRNS 1 mA, 100–640 Hz zero -mean Gaussian random noise). We found that adding noise significantly reduced the mixed percept duration (Exp. 1 and Exp. 2). Our results are the first to demonstrate that both central and peripheral noise can influence state-switching dynamics of binocular rivalry under specific conditions (e.g. low visual contrast stimuli), in line with a SR-mechanism

Altering brain dynamics with transcranial random noise stimulation

AbstractRandom noise can enhance the detectability of weak signals in nonlinear systems, a phenomenon known as stochastic resonance (SR). This concept is not only applicable to single threshold systems but can also be applied to dynamical systems with multiple attractor states, such as observed during the phenomenon of binocular rivalry. Binocular rivalry can be characterized by marginally stable attractor states between which the brain switches in a spontaneous, stochastic manner. Here we used a computational model to predict the effect of noise on perceptual dominance durations. Subsequently we compared the model prediction to a series of experiments where we measured binocular rivalry dynamics when noise (zero-mean Gaussian random noise) was added either to the visual stimulus (Exp. 1) or directly to the visual cortex (Exp. 2) by applying transcranial Random Noise Stimulation (tRNS 1 mA, 100–640 Hz zero -mean Gaussian random noise). We found that adding noise significantly reduced the mixed percept duration (Exp. 1 and Exp. 2). Our results are the first to demonstrate that both central and peripheral noise can influence state-switching dynamics of binocular rivalry under specific conditions (e.g. low visual contrast stimuli), in line with a SR-mechanism.</jats:p