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Copyright © 2020 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved. 936 www.ccmjournal.org June 2020 • Volume 48 • Number 6 Neurologic complications are associated with significantly increased morbidity and mortality in extracorporeal membrane oxygenation (ECMO) patients. The reported prevalence of neurologic complications, particularly ischemic stroke, intracranial hemorrhage, and brain death, is highly variable during adult ECMO. For adult venoarterial ECMO patients, previous meta-analyses have estimated a cumulative rate of 13.3% for all reported neurologic complications and 5.9% to 7.8% for ischemic and/or hemorrhagic stroke. Recent data from the multicenter Extracorporeal Life Support Organization (ELSO) registry reported a peak prevalence of neurologic complications of 20% in 2002–2004, which decreased to 13% in 2011–2013 (1). Intracranial hemorrhage was associated with a 10.5% hospital survival rate in adult venoarterial ECMO patients in the ELSO registry (2). Lack of standardized diagnostic criteria to report neurologic complications in ECMO registries likely underestimates the true prevalence of neurologic complications in ECMO. Furthermore, it is challenging to determine whether these neurologic injuries are related to the specific diagnostic indication for ECMO (cardiac arrest, cardiogenic shock, severe hypoxemia, acute respiratory distress syndrome [ARDS]) or whether they are attributable to ECMO treatment. There is no question that large gaps exist in our knowledge of ECMO-related neurologic complications (3). In this issue of Critical Care Medicine, Cho et al (4) present results from a retrospective cohort study of adult ECMO patients who had undergone brain autopsy over a 10-year period (2009–2018) at a single tertiary medical center with a high prevalence of acute brain injury. They also describe difference in the neuropathology findings and neurologic examination/ electroencephalogram (EEG) in four of these patients (5). A previous retrospective single-center study (Mayo Clinic, Rochester, MN) reported that of 87 adults treated with ECMO, neurologic events occurred in 42 patients (50%), with diagnoses including subarachnoid hemorrhage, ischemic watershed infarctions, hypoxic-ischemic encephalopathy, unexplained coma, and brain death. Although stroke was rarely diagnosed clinically, nine of 10 brain autopsies confirmed hypoxic-ischemic and hemorrhagic lesions of vascular origin (6). Neurologic events were associated with higher age and more severe hypoxemia. Autopsy studies of the brains of ECMO-treated adults are few, and the information provided in the current study by Cho et al (4) adds to our knowledge of this important topic. But several limitations are also noted: