Badi, Mohammed K.

Introduction: Poor leptomeningeal collateral flow is related to worse neurological outcome in acute ischemic stroke. The increased release of stress hormones during the first hours of acute stroke leads to inhibition of insulin secretion and increase insulin resistance, thus inducing stress hyperglycemia, which is often evident on blood glucose levels at admission. While admission hyperglycemia, independent of diabetes mellitus (DM) is associated with poor clinical outcome in ischemic stroke, studies on its effect on collateral circulation after acute cerebral embolism are largely inconclusive. Methods: We identified a consecutive series of patients aged 18 years and older from 2008 to 2018 with acute embolic large vessel stroke confirmed on CT angiography (CTA) using an institutional database. Individual CTAs were over-read, and collateral scores of the affected hemisphere were calculated using a modification of the Tan scale (0-4), by two trained readers. We reviewed the electronic medical records for presenting NIHSS, admission glucose and HbA1C levels, and prior history of DM. Spearman’s ρ, odds ratios (OR), and their 95% confidence intervals (CI) were analyzed. All tests were considered significant when P<0.05. Results: Of the 405 patients identified through the database (mean age 70 years [range, 55-85], 45% [183/405] women), 35% (142/405) had a prior history of DM. Mean admission glucose was 134±51 mg/dL, and median NIHSS at presentation was 17. Blood glucose level at admission was negatively correlated with collateral scores (ρ= -0.23, P=0.008). Specifically, glucose levels above 120 mg/dL were significantly associated (OR 1.68 CI 1.13-2.5) with poor collateral scores (≤1). However, collateral scores exhibited no statistically significant relationship with HbA1c (ρ=-0.08, P=0.15) or prior history of DM (P=0.73). Conclusions: Patients with higher admission glucose levels have poor collateral scores, while HbA1c and prior DM do not have a similar effect on collateral flow. Our results suggest that poor collateral flow may explain adverse outcomes associated with hyperglycemia in acute ischemic stroke. Determining if there is a benefit of aggressive glycemic control within the first few hours of embolic stroke warrants further study.

Introduction: Good collateral flow is associated with improved outcomes in acute embolic stroke. There is compelling data linking smoking to all types of stroke, with current smokers at a higher risk than former or never smokers. Smoking has, however, been shown to promote collaterals in coronary vascular bed in humans. It is unknown if there is a similar effect in cerebral collateral flow. We aimed to investigate if cigarette smoking was positively associated with collateral blood flow in a homogenous cohort of patients with acute large vessel occlusive embolic stroke. Methods: We identified all patients aged ≥18 with acute ischemic stroke showing embolic occlusion of ICA terminus/M1 MCA on admission CT angiography (CTA), between 2008 to 2018, through an institutional database. Patients with chronic occlusions and stenotic lesions were excluded. Individual CTAs were independently reviewed by two trained investigators to calculate collateral scores of the affected hemisphere using the modified Tan scale (0-4) as a reference. Details of cigarette smoking history were obtained from the electronic medical records. Patients were grouped into smokers (former and current smokers) and never smokers. Odds ratios (OR) and their 95% confidence intervals (CI) were estimated, and all tests were considered significant when P<0.05. Results: Of the 612 patients identified through the database, 429/612 patients (mean age 71±16 years, 45% [194/429] women) satisfied the inclusion criteria. 64.8% (278/429) had a positive history of smoking with an average of 47±12 pack-years. There was a significant association between good collateral scores (≥2) with smoking history (OR 1.74 CI 1.17-2.61, P=0.006). This trend remained significant even after comparing raw collateral scores (0-4) ( P=0.006, Spearman’s ρ=0.22). However, number of pack-years and collateral scores exhibited no statistically significant relationship (P=0.6). Conclusions: Our study shows that patients who have ever smoked have higher intracranial collateral vessel scores in the event of an acute embolic stroke. Increased impedance and reduced cerebral blood flow resulting from cigarette smoking may stimulate collateral recruitment in cerebral pial circulation, similar to the effect in coronary bed.