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Background and purpose Relative signal intensity of acute ischemic stroke lesions in fluid-attenuated inversion recovery (FLAIR-rSI) magnetic resonance imaging is associated with time elapsed since stroke onset with higher intensities signifying longer time intervals. In the randomized controlled WAKE-UP trial, intravenous alteplase was effective in patients with unknown onset stroke selected by visual assessment of DWI-FLAIR mismatch, i.e., in those with no marked FLAIR hyperintensity in the region of the acute DWI lesion. In this post-hoc analysis, we investigated if quantitatively measured FLAIR-rSI modifies treatment effect of intravenous alteplase. Methods FLAIR-rSI of stroke lesions was measured relative to signal intensity in a mirrored region in the contralesional hemisphere. The relationship between FLAIR-rSI and treatment effect on functional outcome assessed by the modified Rankin Scale (mRS) after 90 days was analysed by binary logistic regression using different endpoints, i.e., favourable outcome defined as mRS 0-1, independent outcome defined as mRS 0-2, ordinal analysis of mRS scores (shift analysis). All models were adjusted for NIHSS at symptom onset and stroke lesion volume. Results FLAIR-rSI was successfully quantified in stroke lesions in 433 patients (86% of 503 patients included in WAKE-UP). Mean FLAIR-rSI was 1.06 (SD 0.09). Interaction of FLAIR-rSI and treatment effect was not significant for mRS 0-1 (p=0.169) and shift analysis (p=0.086), but 2 reached significance for mRS 0-2 (p=0.004). We observed a smooth continuing trend of decreasing treatment effects in relation to clinical endpoints with increasing FLAIR-rSI. Conclusion In patients in whom no marked parenchymal FLAIR hyperintensity was detected by visual judgement in the WAKE-UP trial, higher FLAIR-rSI of DWI lesions was associated with decreased treatment effects of intravenous thrombolysis. This parallels the known association of treatment effect and elapsing time of stroke onset.

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Telemedicine networks facilitate acute-phase neurological assessment and prevent unnecessary secondary interhospital transfers.

Objectives: Mechanical thrombectomy (MT) is an effective treatment for acute ischemic stroke (AIS) caused by large vessel occlusion. Recanalization time is a key factor in the treatment of AIS. It has previously been suggested that intravenous thrombolysis (IVT) may be associated with a shorter recanalization time. The aim of our study was to investigate whether IVT or other factors could be associated with shorter or longer MT procedure times. Methods: We performed a retrospective analysis of a local cohort of patients treated by MT. We collected procedure time (puncture to recanalization and clot visualization to recanalization), demographic data, localization of the thrombus, antithrombotic treatment at arrival, IVT infusion, and stroke subtype at discharge according to the TOAST classification. We planned to analyze the full cohort and the successful revascularization subgroup. Results: There was no difference in procedure times between patients who received IVT and those who did not. In the successful revascularization subgroup, patients presenting with cardioembolic stroke had a significantly shorter time between clot visualizations and revascularization than the other patients (41 vs. 56 min, p = 0.024), but this was not the case in the full cohort. Also in the successful revascularization subgroup, the revascularization time was 76 vs. 61 min (p = 0.075) in patients presenting with tandem occlusion vs. the others, but there was no difference between these groups in the full cohort. Conclusions: There was no difference in terms of procedure times in patients treated by IVT and MT vs. patients treated by MT alone either in the full cohort or in the successful revascularization subgroup. The data from the successful revascularization subgroup may be useful for studying revascularization times, provided that data from procedures that were stopped prematurely by the operator due to the length of time since symptom onset is removed.