Bettina Lara Serrallach

BACKGROUND: The optimal management of isolated posterior cerebral artery occlusion (iPCAO) remains unclear. We investigated whether baseline perfusion imaging parameters are associated with clinical outcomes and whether they modify the association between endovascular therapy (EVT) and outcomes in iPCAO. METHODS: This prespecified secondary analysis of the international, multicenter, observational PLATO (Posterior Cerebral Artery Occlusion) registry (35 centers, 10 countries, 2015–2025) included consecutive adults with unilateral iPCAO and baseline perfusion imaging (computed tomography or magnetic resonance imaging) with reconstructed parameters. The primary end point was an excellent 90-day outcome (modified Rankin Scale score, 0–1). Perfusion parameters included hypoperfusion volume, infarct core volume, and mismatch ratio. The primary analysis used multivariable mixed-effects regression models (center as random effect) to assess associations between perfusion parameters and outcomes, adjusting for age, sex, treatment year, prestroke modified Rankin Scale score, baseline National Institutes of Health Stroke Scale score, diabetes, stroke cause, posterior circulation Acute Stroke Prognosis Early Computed Tomography Score, occlusion site, intravenous thrombolysis, and onset-to-door time. To test whether the association between EVT and outcomes varies according to baseline perfusion parameters, we evaluated treatment-by-perfusion interactions by including interaction terms (treatment×perfusion parameter) in inverse probability of treatment weighting–adjusted models, with results expressed as ratios of odds ratios (ORs). RESULTS: Of 1811 patients with iPCAO, 443 met inclusion criteria (median age, 74 years; 41.8% female). Larger hypoperfusion volume was associated with lower odds of excellent outcome (adjusted OR, 0.72 [95% CI, 0.58–0.89] per 1-unit increase in natural logarithm–transformed volume). No interaction between perfusion parameters and EVT was observed for the primary outcome. However, increasing core volume was associated with a progressively less favorable modified Rankin Scale score shift (ratio of OR, 0.66 [95% CI, 0.48–0.90]; P _interaction =0.009) and higher mortality (ratio of OR, 1.82 [95% CI, 1.10–3.03]; P _interaction =0.021) with EVT compared with medical management. Increasing hypoperfusion volume was associated with a higher risk of symptomatic intracranial hemorrhage with EVT (ratio of OR, 10.15 [95% CI, 1.06–96.93]; P _interaction =0.044). CONCLUSIONS: In iPCAO, perfusion imaging provides independent prognostic information but does not identify patients with potential benefit from EVT and may instead indicate those at higher procedural risk. REGISTRATION: URL: https://osf.io/62mwt ; Unique identifier: NCT05291637.

Auditory perception is essential for human communication and development, influencing cognitive and social functions. Electroencephalography (EEG) has long been used to examine auditory evoked potentials (AEPs), while magnetoencephalography (MEG) has more recently enabled the investigation of auditory evoked fields (AEFs), providing complementary spatial detail. However, MEG’s high costs and operational complexity limit its accessibility. In this study, we adapted analysis protocols originally developed for MEG to EEG in order to explore their applicability in a more accessible and cost-effective modality. We examined auditory evoked potentials in response to instrumental tones among adults (N=12) using EEG and compared the results with previously published MEG data. Our findings suggest that EEG can approximate MEG-based methodologies, demonstrating similar mean latencies and standard errors for P1, N1, and P2 components. Despite slight variations in standard errors, likely due to the smaller sample size, the results support EEG’s continued value for broader application in auditory neuroscience. The accessibility of EEG opens opportunities for large-scale studies, enhancing our understanding of auditory perception across diverse populations. This approach may also contribute to the development of diagnostics and tailored interventions for auditory-related conditions, including ADHD and dyslexia

Background: Subarachnoid hyperdensities (SH) on flat-detector CT (FDCT) after mechanical thrombectomy (MT) are associated with less favorable clinical outcomes. We aimed to further elucidate the prevalence and clinical significance of SH following MT, especially in patients with dominant, co- and non-dominant M2 occlusions. Methods: 728 patients from two comprehensive stroke centers were assessed for the presence of SH on FDCT. The primary outcome was the presence of SH on FDCT. The secondary outcome was modified Rankin Scale scores (mRS) at 90 days. Baseline procedural characteristics and clinical outcomes were analyzed using group comparisons and multivariable logistic regression. To remove the effect of confounding factors, a logistic regression model was built using inverse probability weighting. Results: In total, 411 patients were included. Prevalence of SH on FDCT was 171/411 (41.6 %), with particularly high prevalence in co- and non-dominant M2 occlusions (63%) and dominant M2 occlusions (53.9%). The occurrence of SH was independently associated with poor functional outcomes (adjusted OR for mRS at 90 days: 1.5; 95% CI, 1.1–2.2) and increased mortality (aOR: 1.7; 95% CI, 1.0–2.8). Increased risk of developing SH was particularly evident in patients with co- and non-dominant M2 occlusions (P < 0.001 OR = 3.78; 95% CI, 2.18–6.57) and dominant M2 occlusions (P < 0.001 OR = 3.07; 95% CI, 1.68–5.59) compared to large vessel occlusions. A higher number of device passes, specifically between 3 and 6 and more than 6, show an effect on the occurrence of SH P < 0.001 OR = 2.75; 95% CI, 1.56–4.84 and P = 0.02 OR = 3.45; 95% CI, 1.17–10.16 compared to fewer passes (1–3). Conclusion: SH are common after MT, especially in M2 occlusions. They are associated with poorer functional outcomes in patients with co- and non-dominant M2 occlusions and higher numbers of device passes (>3).

BACKGROUND: A third of endovascularly treated patients with stroke experience incomplete reperfusion (expanded Thrombolysis in Cerebral Infarction [eTICI] <3), and the natural evolution of this incomplete reperfusion remains unknown. We systematically reviewed the literature and performed a meta-analysis on the natural evolution of incomplete reperfusion after endovascular therapy. METHODS: A systematic review of MEDLINE, Embase, and PubMed up until March 1, 2024, using a predefined strategy. Only full-text English-written articles reporting rates of either favorable (ie, delayed reperfusion (DR) or no new infarct) or unfavorable progression (ie, persistent perfusion deficit or new infarct) of incompletely reperfused tissue were included. The primary outcome was the rate of DR and its association with functional independence (modified Rankin Scale score, 0–2) at 90 days postintervention. Pooled odds ratios with 95% CIs were calculated using a random-effects model. RESULTS: Six studies involving 950 patients (50.7% female; median age, 71 years; interquartile range, 60–79) were included. Four studies assessed the evolution of incomplete reperfusion on magnetic resonance imaging perfusion imaging, while 2 studies used diffusion-weighted imaging and noncontrast computed tomography imaging, where new infarct was used to denote unfavorable progression. Five studies defined incomplete reperfusion as eTICI 2b50 or 2c. DR occurred in 41% (interquartile range, 33%–51%) of cases 24 hours postintervention. Achieving DR was associated with a higher likelihood of functional independence at 90 days (odds ratio, 2.5 [95% CI, 1.9–3.4]). CONCLUSIONS: Nearly half of eTICI <3 patients achieve DR, leading to favorable clinical outcomes. This subgroup may derive limited or potentially harmful effects from pursuing additional reperfusion strategies (eg, intra-arterial lytics or secondary thrombectomy). Accurately predicting the evolution of incomplete reperfusion could optimize patient selection for adjunctive reperfusion strategies at the end of an intervention. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifiers: NCT05499832.

BACKGROUND: Perfusion abnormalities in the infarct and salvaged penumbra have been proposed as a potential reason for poor clinical outcome (modified Rankin Scale score >2) despite complete angiographic reperfusion (Thrombolysis in Cerebral Infarction [TICI3]). In this study, we aimed to identify different microvascular perfusion patterns and their association with clinical outcomes among TICI3 patients. METHODS: University Hospital Bern’s stroke registry of all patients between February 2015 and December 2021. Macrovascular reperfusion was graded using the TICI scale. Microvascular reperfusion status was evaluated within the infarct area on cerebral blood volume and cerebral blood flow perfusion maps obtained 24-hour postintervention. Primary outcome was functional independence (90-day modified Rankin Scale score 0–2) evaluated with the logistic regression analysis adjusted for age, sex, and 24-hour infarct volume from follow-up imaging. RESULTS: Based on microvascular perfusion findings, the entire cohort (N=248) was stratified into one of the 4 clusters: (1) normoperfusion (no perfusion abnormalities; n=143/248); (2) hyperperfusion (hyperperfusion on both cerebral blood volume and cerebral blood flow; n=54/248); (3) hypoperfusion (hypoperfusion on both cerebral blood volume and cerebral blood flow; n=14/248); and (4) mixed (discrepant findings, eg, cerebral blood volume hypoperfusion and cerebral blood flow hyperperfusion; n=37/248). Compared with the normoperfusion cluster, patients in the hypoperfusion cluster were less likely to achieve functional independence (adjusted odds ratio, 0.3 [95% CI, 0.1–0.9]), while patients in the hyperperfusion cluster tended to have better outcomes (adjusted odds ratio, 3.3 [95% CI, 1.3–8.8]). CONCLUSIONS: In around half of TICI3 patients, perfusion abnormalities on the microvascular level can be observed. Microvascular hypoperfusion, despite complete macrovascular reperfusion, is rare but may explain the poor clinical course among some TICI3 patients, while a detrimental effect of hyperperfusion after reperfusion could not be confirmed.

BACKGROUND AND PURPOSE: Flat-panel detector computed tomography (FDCT) immediately after mechanical thrombectomy (MT) can detect complications including early hemorrhagic transformation and subarachnoid hyperdensities (SH). The clinical significance of SH in patients undergoing MT remains unclear. MATERIALS AND METHODS: We studied 223 patients who underwent MT for anterior circulation stroke, had FDCT performed immediately after the procedure, and had follow-up imaging within 24 hours. SH severity was categorized into 5 grades (SH 0: absent to SH IV: extensive). Baseline and procedural characteristics, as well as outcome measures, were analyzed using group comparisons and multivariable logistic regression analyses. RESULTS: Overall, 100/223 (45%) of patients showed SH on immediate post-interventional FDCT. The factors associated with an increased SH risk were: medium vessel occlusion or distal vessel occlusion as compared to a large vessel occlusion, a more distal device position, a higher number of device passes, a larger volume of contrast applied, and worse final reperfusion eTICI. Occurrence of SH grade II-IV was independently associated with worse functional outcomes (aOR for mRS 3-6: 2.2, 95% CI 1.1-4.3), whereas patients with SH grade I had similar outcomes to patients without SH. CONCLUSIONS: Our study identified risk factors for SH, most of which reflect increasingly challenging procedures or more peripheral recanalization attempts. The presence of SH grades II-IV was associated with poorer outcomes, suggesting the need for personalized strategies to reduce its incidence and severity or potentially improve recovery after SH. ABBREVIATIONS: DVO = distal vessel occlusion; FDCT = flat-panel detector computed tomography; LVO = large vessel occlusion; MVO = medium vessel occlusion; MT = mechanical thrombectomy; SH = subarachnoid hyperdensities

Purpose: Flat-panel detector computed tomography (FDCT) is increasingly used in (neuro)interventional angiography suites. This study aimed to compare FDCT perfusion (FDCTP) with conventional multidetector computed tomography perfusion (MDCTP) in patients with acute ischemic stroke. Methods: In this study, 19 patients with large vessel occlusion in the anterior circulation who had undergone mechanical thrombectomy, baseline MDCTP and pre-interventional FDCTP were included. Hypoperfused tissue volumes were manually segmented on time to maximum (Tmax) and time to peak (TTP) maps based on the maximum visible extent. Absolute and relative thresholds were applied to the maximum visible extent on Tmax and relative cerebral blood flow (rCBF) maps to delineate penumbra volumes and volumes with a high likelihood of irreversible infarcted tissue (“core”). Standard comparative metrics were used to evaluate the performance of FDCTP. Results: Strong correlations and robust agreement were found between manually segmented volumes on MDCTP and FDCTP Tmax maps (r = 0.85, 95% CI 0.65–0.94, p < 0.001; ICC = 0.85, 95% CI 0.69–0.94) and TTP maps (r = 0.91, 95% CI 0.78–0.97, p < 0.001; ICC = 0.90, 95% CI 0.78–0.96); however, direct quantitative comparisons using thresholding showed lower correlations and weaker agreement (MDCTP versus FDCTP Tmax 6 s: r = 0.35, 95% CI −0.13–0.69, p = 0.15; ICC = 0.32, 95% CI 0.07–0.75). Normalization techniques improved results for Tmax maps (r = 0.78, 95% CI 0.50–0.91, p < 0.001; ICC = 0.77, 95% CI 0.55–0.91). Bland-Altman analyses indicated a slight systematic underestimation of FDCTP Tmax maximum visible extent volumes and slight overestimation of FDCTP TTP maximum visible extent volumes compared to MDCTP. Conclusion: FDCTP and MDCTP provide qualitatively comparable volumetric results on Tmax and TTP maps; however, direct quantitative measurements of infarct core and hypoperfused tissue volumes showed lower correlations and agreement.

BACKGROUND AND PURPOSE: Potential utility of flat panel CT perfusion imaging (FPCT-PI) performed immediately after mechanical thrombectomy (MT) is unknown. We aimed to assess whether FPCT-PI obtained directly post-MT could provide additional potentially relevant information on tissue reperfusion status. MATERIALS AND METHODS: This was a single-center analysis of all patients with consecutive acute stroke admitted between June 2019 and March 2021 who underwent MT and postinterventional FPCT-PI (n = 26). A core lab blinded to technical details and clinical data performed TICI grading on postinterventional DSA images and qualitatively assessed reperfusion on time-sensitive FPCT-PI maps. According to agreement between DSA and FPCT-PI, all patients were classified into 4 groups: hypoperfusion findings perfectly matched by location (group 1), hypoperfusion findings mismatched by location (group 2), complete reperfusion on DSA with hypoperfusion on FPCT-PI (group 3), and hypoperfusion on DSA with complete reperfusion on FPCT-PI (group 4). RESULTS: Detection of hypoperfusion (present/absent) concurred in 21/26 patients. Of these, reperfusion findings showed perfect agreement on location and size in 16 patients (group 1), while in 5 patients there was a mismatch by location (group 2). Of the remaining 5 patients with disagreement regarding the presence or absence of hypoperfusion, 3 were classified into group 3 and 2 into group 4. FPCT-PI findings could have avoided TICI overestimation in all false-positive operator-rated TICI 3 cases (10/26). CONCLUSIONS: FPCT-PI may provide additional clinically relevant information in a considerable proportion of patients undergoing MT. Hence, FPCT-PI may complement the evaluation of reperfusion efficacy and potentially inform decision-making in the angiography suite.

BACKGROUND AND PURPOSE: Intra-arterial thrombolytics may be used to treat distal vessel occlusions, which cause incomplete reperfusion following mechanical thrombectomy. Because immediate reperfusion after intra-arterial thrombolytics occurs rarely, the aim of this study was to assess the delayed effect of intra-arterial thrombolytics using follow-up perfusion imaging. MATERIALS AND METHODS: We included patients from a prospective stroke registry (February 2015 to September 2022) who had undergone mechanical thrombectomy and had incomplete reperfusion (expanded TICI 2a–2c) and available 24 hour perfusion imaging. Perfusion imaging was rated as delayed reperfusion if time-sensitive perfusion maps did not show wedge-shaped delays suggestive of persisting occlusions corresponding to the post-mechanical thrombectomy angiographic deficit. Patients treated with intra-arterial thrombolytics were compared with controls using multivariable logistic regression and inverse probability of treatment weighting matching for baseline differences and factors associated with delayed reperfusion. RESULTS: The median age of the final study population (n = 459) was 74 years (interquartile range, 63–81 years), and delayed reperfusion occurred in 61% of cases. Patients treated with additional intra-arterial thrombolytics (n = 40) were younger and had worse expanded TICI scores. After matching was performed, intra-arterial thrombolytics was associated with higher rates of delayed reperfusion (adjusted OR = 2.7; 95% CI, 1.1–6.4) and lower rates of new infarction in the residually hypoperfused territory after mechanical thrombectomy (adjusted OR = 0.3; 95% CI, 0.1–0.7). No difference was found in the rates of functional independence (90-day mRS, 0–2; adjusted OR = 1.4; 95% CI, 0.4–4.1). CONCLUSIONS: Rescue intra-arterial thrombolytics is associated with delayed reperfusion of remaining vessel occlusions following incomplete mechanical thrombectomy. The value of intra-arterial thrombolytics as a potential therapy for incomplete reperfusions after mechanical thrombectomy should be assessed in the setting of randomized controlled trials.