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Objective:To determine the sensitivity of T2*weighted gradient-echo (T2*GRE) and inversion recovery turbo-field-echo (TFE) sequences for cortical multiple sclerosis lesions at 7 T. Design, Setting, and Participants: Autopsied brain tissue from individuals with multiple sclerosis was scanned with 3-dimensional T2*GRE and 3-dimensional inversion recovery white matter-attenuated TFE sequences at 7 T. Cortical lesions visible with either sequence were scored for each anatomical lesion type. Imaged brain tissue was then processed for immunohistochemical analysis, and cortical lesions were identified by labeling with antibody against myelin basic protein and CD68 for microglia. Magnetic resonance images were matched with corresponding histological sections and scored retrospectively to determine the sensitivity for each cortical lesion type.Main Outcome Measure: Cortical lesion detection by 3-dimensional T2*GRE and white matter-attenuated TFE sequences. Results:The 3-dimensional T2*GRE and white matterattenuated TFE sequences retrospectively detected 93% and 82% of all cortical lesions, respectively (with varying sensitivities for different lesion types). Lesion visibility was primarily determined by size as all undetected lesions were smaller than 1.1 mm at their smallest diameter. The T2*GRE images showed hypointense rings in some cortical lesions that corresponded with increased density of activated microglia.Conclusions: Three-dimensional T2*GRE and white matter-attenuated TFE sequences at a 7-T field strength detect most cortical lesions in postmortem multiple sclerosis tissue. This study indicates the potential of T2*GRE and white matter-attenuated TFE sequences in ultrahigh-field magnetic resonance imaging for cortical lesion detection in patients with multiple sclerosis.

Background: Anecdotal reports suggest fewer patients with stroke symptoms are presenting to hospitals during the coronavirus disease 2019 (COVID-19) pandemic. We quantify trends in stroke code calls and treatments at 3 Connecticut hospitals during the local emergence of COVID-19 and examine patient characteristics and stroke process measures at a Comprehensive Stroke Center (CSC) before and during the pandemic. Methods: Stroke code activity was analyzed from January 1 to April 28, 2020, and corresponding dates in 2019. Piecewise linear regression and spline models identified when stroke codes in 2020 began to decline and when they fell below 2019 levels. Patient-level data were analyzed in February versus March and April 2020 at the CSC to identify differences in patient characteristics during the pandemic. Results: A total of 822 stroke codes were activated at 3 hospitals from January 1 to April 28, 2020. The number of stroke codes/wk decreased by 12.8/wk from February 18 to March 16 ( P =0.0360) with nadir of 39.6% of expected stroke codes called from March 10 to 16 (30% decrease in total stroke codes during the pandemic weeks in 2020 versus 2019). There was no commensurate increase in within-network telestroke utilization. Compared with before the pandemic (n=167), pandemic-epoch stroke code patients at the CSC (n=211) were more likely to have histories of hypertension, dyslipidemia, coronary artery disease, and substance abuse; no or public health insurance; lower median household income; and to live in the CSC city ( P <0.05). There was no difference in age, sex, race/ethnicity, stroke severity, time to presentation, door-to-needle/door-to-reperfusion times, or discharge modified Rankin Scale. Conclusions: Hospital presentation for stroke-like symptoms decreased during the COVID-19 pandemic, without differences in stroke severity or early outcomes. Individuals living outside of the CSC city were less likely to present for stroke codes at the CSC during the pandemic. Public health initiatives to increase awareness of presenting for non-COVID-19 medical emergencies such as stroke during the pandemic are critical.

Background and Purpose— Sex differences in stroke incidence over time were previously reported from the GCNKSS (Greater Cincinnati/Northern Kentucky Stroke Study). We aimed to determine whether these differences continued through 2015 and whether they were driven by particular age groups. Methods— Within the GCNKSS population of 1.3 million, incident (first ever) strokes among residents ≥20 years of age were ascertained at all local hospitals during 5 periods: July 1993 to June 1994 and calendar years 1999, 2005, 2010, and 2015. Out-of-hospital cases were sampled. Sex-specific incidence rates per 100 000 were adjusted for age and race and standardized to the 2010 US Census. Trends over time by sex were compared (overall and age stratified). Sex-specific case fatality rates were also reported. Bonferroni corrections were applied for multiple comparisons. Results— Over the 5 study periods, there were 9733 incident strokes (56.3% women). For women, there were 229 (95% CI, 215–242) per 100 000 incident strokes in 1993/1994 and 174 (95% CI, 163–185) in 2015 ( P <0.05), compared with 282 (95% CI, 263–301) in 1993/1994 to 211 (95% CI, 198–225) in 2015 ( P <0.05) in men. Incidence rates decreased between the first and last study periods in both sexes for IS but not for intracerebral hemorrhage or subarachnoid hemorrhage. Significant decreases in stroke incidence occurred between the first and last study periods for both sexes in the 65- to 84-year age group and men only in the ≥85-year age group; stroke incidence increased for men only in the 20- to 44-year age group. Conclusions— Overall stroke incidence decreased from the early 1990s to 2015 for both sexes. Future studies should continue close surveillance of sex differences in the 20- to 44-year and ≥85-year age groups, and future stroke prevention strategies should target strokes in the young- and middle-age groups, as well as intracerebral hemorrhage.

Background and Purpose Stroke mortality is 30% higher in the rural US. This could be due to either higher incidence or higher case-fatality from stroke in rural areas. Methods The urban-rural status of 23,280 stroke-free participants recruited between 2003 and 2007 in the REasons for Geographic And Racial Differences in Stroke (REGARDS) study was classified using the Rural/Urban Commuting Area scheme as residing in urban, large rural town/city, or small rural town or isolated areas. The risk of incident stroke was assessed using proportional hazards analysis, and case-fatality (death within 30 days of stroke) was assessed using logistic regression. Models were adjusted for demographics, traditional stroke risk factors, and measures of socio-economic status (SES). Results After adjustment for demographic factors and relative to urban areas, stroke incidence was 1.23-times higher (95% CI: 1.01 – 1.51) in large rural town/cities, and 1.30-times higher (95% CI: 1.03 – 1.62) in small rural towns or isolated areas. Adjustment for risk factors and SES only modestly attenuated this association, and the association became marginally non-significant (p = 0.071). There was no association of rural-urban status with case-fatality (p > 0.47). Conclusions The higher stroke mortality in rural regions appeared to be attributable to higher stroke incidence rather than case fatality. A higher prevalence of risk factors and lower SES only modestly contributed to the increased risk of incident stroke risk in rural areas. There was no evidence of higher case-fatality in rural areas.

Background and Purpose— Loss of cerebral autoregulation in the acute phase of ischemic stroke leaves patients vulnerable to blood pressure (BP) changes. Effective BP management after endovascular thrombectomy may protect the brain from hypoperfusion or hyperperfusion. In this observational study, we compared personalized, autoregulation-based BP targets to static systolic BP thresholds. Methods— We prospectively enrolled 90 patients undergoing endovascular thrombectomy for stroke. Autoregulatory function was continuously measured by interrogating changes in near-infrared spectroscopy–derived tissue oxygenation (a cerebral blood flow surrogate) in response to changes in mean arterial pressure. The resulting autoregulatory index was used to trend the BP range at which autoregulation was most preserved. Percent time that mean arterial pressure exceeded the upper limit of autoregulation or decreased below the lower limit of autoregulation was calculated for each patient. Time above fixed systolic BP thresholds was computed in a similar fashion. Functional outcome was measured with the modified Rankin Scale at 90 days. Results— Personalized limits of autoregulation were successfully computed in all 90 patients (age 71.6±16.2, 47% female, mean National Institutes of Health Stroke Scale 13.9±5.7, monitoring time 28.0±18.4 hours). Percent time with mean arterial pressure above the upper limit of autoregulation associated with worse 90-day outcomes (odds ratio per 10% 1.84 [95% CI, 1.3–2.7] P =0.002), and patients with hemorrhagic transformation spent more time above the upper limit of autoregulation (10.9% versus 16.0%, P =0.042). Although there appeared to be a nonsignificant trend towards worse outcome with increasing time above systolic BP thresholds of 140 mm Hg and 160 mm Hg, the effect sizes were smaller compared with the personalized approach. Conclusions— Noninvasive determination of personalized BP thresholds for stroke patients is feasible. Deviation from these limits may increase risk of further brain injury and poor functional outcome. This approach may present a better strategy compared with the classical approach of maintaining systolic BP below a predetermined value, though a randomized trial is needed to determine the optimal approach for hemodynamic management.

Background and Purpose— We aimed to compare functional and procedural outcomes of patients with acute ischemic stroke with none-to-minimal (modified Rankin Scale [mRS] score, 0–1) and moderate (mRS score, 2–3) prestroke disability treated with mechanical thrombectomy. Methods— Consecutive adult patients undergoing mechanical thrombectomy for an anterior circulation stroke were prospectively identified at 2 comprehensive stroke centers from 2012 to 2018. Procedural and 90-day functional outcomes were compared among patients with prestroke mRS scores 0 to 1 and 2 to 3 using χ 2 , logistic, and linear regression tests. Primary outcome and significant differences in secondary outcomes were adjusted for prespecified covariates. Results— Of 919 patients treated with mechanical thrombectomy, 761 were included and 259 (34%) patients had moderate prestroke disability. Ninety-day mRS score 0 to 1 or no worsening of prestroke mRS was observed in 36.7% and 26.7% of patients with no-to-minimal and moderate prestroke disability, respectively (odds ratio, 0.63 [0.45–0.88], P =0.008; adjusted odds ratio, 0.90 [0.60–1.35], P =0.6). No increase in the disability at 90 days was observed in 22.4% and 26.7%, respectively. Rate of symptomatic intracerebral hemorrhage (7.3% versus 6.2%, P =0.65), successful recanalization (86.7% versus 83.8%, P =0.33), and median length of hospital stay (5 versus 5 days, P =0.06) were not significantly different. Death by 90 days was higher in patients with moderate prestroke disability (14.3% versus 40.3%; odds ratio, 4.06 [2.82–5.86], P <0.001; adjusted odds ratio, 2.83 [1.84, 4.37], P <0.001). Conclusions— One-third of patients undergoing mechanical thrombectomy had a moderate prestroke disability. There was insufficient evidence that functional and procedural outcomes were different between patients with no-to-minimal and moderate prestroke disability. Patients with prestroke disability were more likely to die by 90 days.

Brain imaging is essential to the clinical management of patients with ischemic stroke. Timely and accessible neuroimaging, however, can be limited in clinical stroke pathways. Here, portable magnetic resonance imaging (pMRI) acquired at very low magnetic field strength (0.064 T) is used to obtain actionable bedside neuroimaging for 50 confirmed patients with ischemic stroke. Low-field pMRI detected infarcts in 45 (90%) patients across cortical, subcortical, and cerebellar structures. Lesions as small as 4 mm were captured. Infarcts appeared as hyperintense regions on T2-weighted, fluid-attenuated inversion recovery and diffusion-weighted imaging sequences. Stroke volume measurements were consistent across pMRI sequences and between low-field pMRI and conventional high-field MRI studies. Low-field pMRI stroke volumes significantly correlated with stroke severity and functional outcome at discharge. These results validate the use of low-field pMRI to obtain clinically useful imaging of stroke, setting the stage for use in resource-limited environments.