Medical Management Versus Surgical Bypass for Symptomatic Intracranial Atherosclerotic Disease: A Systematic Review Adeel Ilyas 1 , Ching-Jen Chen 2 , Natasha Ironside 3 , Thomas J. Buell 2 , Gustavo Chagoya 1 , Philip G. Schmalz 1 , William R. Stetler 1 , Norberto Andaluz 4 , Robert F. James 4 , Dale Ding 4 INTRODUCTION Intracranial atherosclerotic disease (ICAD) is one of the most common causes of stroke worldwide. 1 ICAD is responsible for approximately 10% of all ischemic strokes in Western countries and up to 50% of ischemic strokes in some Asian countries. 1-4 Furthermore, up to 40% of patients with symptomatic ICAD are at risk of recurrent cerebral ischemia within 2 years. 5,6 Treatment options for symptomatic ICAD include medical management (dual antiplatelet therapy and optimization of risk factors), endovascular stenting, and surgical bypass. 7,8 While randomized clinical trials, such as the Stenting versus Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis (SAMMPRIS) and Vitesse Intracranial Stent Study for Ischemic Stroke Therapy (VISSIT) trials, have failed to show a benefit from endovascular treatment of ICAD, there are limited data available regarding the comparative effectiveness of surgical versus medical management of symptomatic ICAD. 9,10 Although the 1985 landmark interna- tional extracranialintracranial (EC-IC) bypass trial failed to demonstrate overall improved outcomes after direct bypass versus medical therapy for ischemic cere- brovascular disease, a subgroup analysis found favorable perioperative and long- term outcomes in patients who underwent bypass for symptomatic ICAD. 11,12 Several retrospective studies also have reported reasonably low rates of perioperative morbidity, recurrent ischemic stroke, and mortality following bypass for symptomatic ICAD. 13-17 In addition, many recent studies have selected surgical candidates by using he- modynamic measurements, the absence of which was a major criticism of the EC-IC bypass trial. 18,19 Therefore, the aim of this systematic review is to compare the outcomes of medical management alone versus surgical bypass for patients with symptomatic ICAD who were treated in the era following the EC-IC bypass trial. - INTRODUCTION: Intracranial atherosclerotic disease (ICAD) is a major cause of stroke worldwide. The optimal management of patients with symp- tomatic ICAD is controversial. Therefore, the aim of this systematic review is to compare medical management versus surgical bypass for the treatment of symptomatic ICAD. - METHODS: A literature review was performed to identify studies reporting outcomes of patients with ICAD who were managed medically or surgically with either direct or indirect bypass. Baseline, treatment, and outcomes data were analyzed. Complications included ischemic stroke, intracranial hemorrhage, and cerebrovascular death. Secondary analyses of the surgically treated cohort were performed to compare the outcomes of direct versus indirect bypass. - RESULTS: The pooled analysis was derived from 18 studies, comprising a total of 2160 patients with ICAD, including 1790 managed medically and 370 treated with surgical bypass. The rates of ischemic stroke, intracranial hem- orrhage, and cerebrovascular death were 16%, 1%, and 4.5% in the medical cohort, respectively, versus 8%, 0.6%, and 1.9% in the surgical cohort, respec- tively. Among patients with ICAD who underwent bypass surgery, the rates of ischemic stroke and cerebrovascular death were 7% and 1.9% in the direct bypass group, respectively, versus 19% and 2.1% in the indirect bypass group, respectively. - CONCLUSIONS: Direct or indirect bypass surgery is a reasonable treatment option for appropriately selected patients with ICAD. Careful preoperative evaluation of hemodynamic parameters and the relevant donor and recipient vessels is crucial to maximizing the success of bypass for ICAD. Further studies remain necessary to clarify the roles of medical versus surgical management for ICAD. Key words - Bypass - Intracranial atherosclerotic disease - Medical - Review - Stroke Abbreviations and Acronyms EC-IC: Extracranialintracranial ICA: Internal carotid artery ICAD: Intracranial atherosclerotic disease MCA: Middle cerebral artery From the 1 Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, Alabama; 2 Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; 3 Department of Neurosurgery, New York-Presbyterian/Columbia University Medical Center, New York, New York; and 4 Department of Neurological Surgery, University of Louisville School of Medicine, Louisville, Kentucky To whom correspondence should be addressed: Adeel Ilyas, M.D. [E-mail: ailyas@uab.edu] Citation: World Neurosurg. (2019) 129:62-71. https://doi.org/10.1016/j.wneu.2019.05.223 Journal homepage: www.journals.elsevier.com/world- neurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved. 62 www.SCIENCEDIRECT.com WORLD NEUROSURGERY, https://doi.org/10.1016/j.wneu.2019.05.223 Literature Review