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BackgroundCircadian variations in the timing of the onset of stroke symptoms have been described, showing a morning excess of cardiovascular risk. To date, no differences have been found between stroke subtype and time distribution throughout the day. The present study aims to compare the seasonal and circadian rhythm of symptoms onset in ischemic, hemorrhagic, and stroke mimic patients.MethodsThis study was conducted prospectively at a hospital and involved a cohort of stroke alert patients from 2018 to 2021. Stroke subtypes were classified as ischemic stroke, intracerebral hemorrhage (ICH), transient ischemic attack (TIA), and stroke mimic. Clinical variables were recorded, and each patient was assigned to a 4-h interval of the day according to the time of onset of symptoms; unwitnessed stroke patients were analyzed separately. Seasonal changes in stroke distribution were analyzed at 3-month intervals.ResultsA total of 2,348 patients were included in this analysis (ischemic 67%, ICH 13%, mimic 16%, and TIA 3%). Regardless of stroke subtype, most of the patients were distributed between 08–12 h and 12–16 h. Significant differences were found in the time distribution depending on stroke subtype, with ICH predominating in the 4–8 h period (dawn), most of which were hypertensive, TIA in the 12–16 h period (afternoon), and stroke mimic in the 20 h period (evening). The ischemic stroke was evenly distributed throughout the different periods of the day. There were no differences in the seasonal pattern between different stroke subtypes, with winter being the one that accumulated the most cases.ConclusionThe present study showed different circadian patterns of stroke subtypes, with a predominance of ICH at dawn and stroke mimic in the afternoon. The stroke circadian rhythm resembles previous studies, with a higher incidence in the morning and a second peak in the afternoon.

Introduction PROMISE trial has shown high predictive accuracy of the N20 somatosensory evoked potential (SEP) response on functional recovery in patients with AIS undergoing endovascular thrombectomy (EVT). This secondary study aims to describe the association between the N20 response and imaging biomarkers of ischemic penumbra, infarct volume and collateral flow. Methods Presence and amplitude of the N20 response was recorded before EVT. At baseline, infarct core was automatically calculated establishing a threshold value of ADC6 sec; and hypoperfusion intensity ratio (HIR) as the proportion of ischemic volume that also has a delay in Tmax>10s. Leptomeningeal collaterals were classified according to the Arterial Collateral Grading Scale in CTA as "poor" (absence and 50%, equal to and greater than the contralateral), or according to the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology scale when the acquired image was dynamic MR angiography, dichotomized as incomplete collateral fill (poor collateral) (grades 0 to 2) and complete collateral fill (optimal collateral) (grades 3 and 4). Collaterals were not evaluated in the conventional angiography since we did not perform a full study to shorten the time to thrombus access. The adjusted predictive value of N20 for functional recovery was analyzed by logistic regression and compared with imaging variables by using receiver operating characteristic curves. Results From 223 patients studied, 99 patients had multimodal imaging with perfusion studies and N20 assessable recordings at baseline (mean age, 70y; median NIHSS, 18), 63 patients with present (N20+) and 36 with absent N20 response (N20‐). Median infarct core was 12 (0‐25) and 16 (3‐60) cc (p= 0,193), ischemic volume 81 (39‐132) and 111 (54‐188) cc (p=0,082) and the HIR 0,4 (0,2‐0,6) 0,4 (0,3‐0,6) (p=0,572), respectively. N20+ was associated to a better collateral flow (OR 2,5; [1,2‐5,3]; p=0,01). N20+ showed the highest predictive capacity of functional recovery at day 7 compared to imaging variables (Table 1) and increased 15 (4‐103) fold the likelihood of good outcome after adjusting for collateral flow 2.94 (1.10‐8.40), ASPECT score (1,17 (0,74 ‐ 1,87) and infarct core 0.98 (0.95‐1.01). Conclusion N20 SEP response is a powerful biomarker of functional recovery that might surrogate advanced imaging in patients with AIS evaluated for endovascular thrombectomy.