Transient Ischemic Attacks Preceding Ischemic Stroke and the Possible Preconditioning of the Human Brain: A Systematic Review and Meta-Analysis.

Sherief Ghozy,Waleed Brinjikji,Ramanathan Kadirvel,David R Holmes,David F Kallmes,Kevin M Kallmes,Salah Eddine Oussama Kacimi,Abdullah Reda,Mohamed Gomaa Sobeeh,Mohamed Elfil,Alejandro A Rabinstein

doi:10.3389/fneur.2021.755167

Abstract

Stroke is a leading cause of mortality and disability worldwide. Transient ischemic attack (TIA) is defined as transient brain ischemia with temporary neurological deficits. In animal models, prior TIA seems to enhance brain ischemic tolerance to withstand further ischemic events, which might be explained by brain preconditioning. Thus, this review aims to formulate evidence of whether TIAs can induce positive preconditioning and enhance the functional outcomes in patients suffering from subsequent ischemic strokes. Five databases were searched (PubMed, Embase, SAGE, Web of Science, and Scopus), and twelve studies were included in the quantitative analysis. Studies were eligible when comparing patients with acute ischemic stroke (AIS) and previous TIA with those with AIS without TIA. Comparisons included the National Institute of Health Stroke Scale (NIHSS) score at admission and 7 days from the stroke event, modified Rankin score (mRS), and Trial of ORG 10,172 in Acute Stroke Treatment (TOAST) classification. Odds ratio (OR), mean difference (MD), and 95% confidence interval (CI) were used to describe our results using the random effect model. Our results revealed that patients with stroke and prior TIAs had lower NIHSS scores at admission than those without prior TIAs. However, the NIHSS score was not significantly different between the two groups at 7 days. Furthermore, there was no statistically significant difference between both groups in terms of mortality. Despite the differences in the admission mRS score groups, patients with prior TIAs had lower mRS scores at discharge.

Highlights

Stroke is one of the most common causes responsible for mortality, morbidity, and loss of function worldwide [1]
Six studies used both modified Rankin score (mRS) and National Institute of Health Stroke Scale (NIHSS) to assess the severity of the disability, seven studies reported the odds of cardioembolism and large vessel stroke in both groups, five studies reported the mortality rate, and three studies reported the odds of small vessel stroke
Understanding the physiological basis of Ischemic preconditioning (IPC) that Transient ischemic attack (TIA) might mediate can open the door for new preventive treatment modalities for patients at high risk of developing ischemic strokes

Summary

Introduction

Stroke is one of the most common causes responsible for mortality, morbidity, and loss of function worldwide [1]. Many management approaches have been extensively reported in the literature, which mainly target decreasing the incidence of severe events and mortality after a stroke event, in addition to enhancing recovery and rehabilitation among the survivors [3,4,5,6]. Ischemia accounts for a significant part of brain tissue injury during stroke, reperfusion contributes to brain tissue damage [7]. Many approaches have been suggested to regulate the process of ischemia-reperfusion and enhance the clinical and prognostic outcomes. Controversies still exist in literature about the potential neuroprotective effects that this approach might have [14]

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