title: The Association of Brain MRI Characteristics and Postoperative Delirium in Cardiac Surgery Patients.
abstract: OBJECTIVE
  Delirium is common after cardiac surgery and is associated with adverse consequences, including cognitive decline. Identification of vulnerable older adults might allow for early implementation of delirium-prevention strategies. Brain MRI findings provide insight into structural brain changes that may identify vulnerable patients. The purpose of this study was to examine the association between brain MRI characteristics potentially associated with delirium vulnerability and the development of postoperative delirium in a nested cohort of patients undergoing cardiac surgery.
  
  
  METHODS
  We identified 79 cardiac surgery patients who had brain MRI imaging after cardiac surgery, as part of an ongoing randomized trial evaluating the efficacy of blood pressure management based on cerebral autoregulation monitoring versus standard management for improving neurological outcomes. Cerebral lateral ventricular size, cortical sulcal width, and white matter hyperintensities (WMH) on brain MRI scans were graded on a validated 0 to 9 scale, and categorized into tertiles. New ischemic lesions were characterized as present or absent. Delirium was assessed using a validated chart-review. Neuropsychological testing performed before surgery was used to establish preoperative cognitive baseline. Multivariable logistic regression was used to assess the independent association between MRI characteristics and postoperative delirium.
  
  
  RESULTS
  The average age of patients was 70.1 ± 7.8 years old, and 72% were male. Twenty-eight of 79 (35.4%) patients developed postoperative delirium. Patients with delirium had higher unadjusted ventricular size (median 4 vs. 3, P = 0.003), and there was a trend towards higher sulcal sizes and WMH grades. Increasing tertiles of ventricular size (Odds Ratio [OR] 3.59; 95% Confidence Interval [CI] 1.59-8.12; P = 0.002) and sulcal size (OR 2.15; 95%CI 1.13-4.12; P = 0.02) were associated with postoperative delirium, with a trend for tertiles of WMH grade (OR 1.91; 95%CI 0.99-3.68; P = 0.05). In multivariable models adjusted for logistic EuroSCORE, baseline cognitive status, bypass time, and any postoperative complication, each tertile of ventricular size was associated with increased odds of postoperative delirium (OR 3.23 per tertile increase in ventricular size; 95%CI 1.21-8.60; P = 0.02). There were no differences in odds of delirium by tertiles of sulcal grade, tertiles of white matter grade, or presence of new ischemic lesions, in adjusted models.
  
  
  CONCLUSIONS
  Increased brain ventricular size was independently associated with delirium after cardiac surgery. These results suggest that cerebral atrophy may contribute to increased vulnerability for postoperative delirium. Baseline brain MRIs may be useful in identifying cardiac surgery patients at high risk for postoperative delirium, who might benefit from targeted perioperative approaches to prevent delirium. ClinicalTrials.gov identifier: NCT00981474.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, John Hopkins School of Medicine, Baltimore, Maryland. Electronic address: cbrownv@jhmi.edu.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Brown
authors.affiliation: Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Roland
authors.initials: R
authors.lastname: Faigle
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Lauren
authors.initials: L
authors.lastname: Klinker
authors.affiliation: Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Mona
authors.initials: M
authors.lastname: Bahouth
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, John Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Laura
authors.initials: L
authors.lastname: Max
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, John Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Andrew
authors.initials: A
authors.lastname: LaFlam
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Karin J
authors.initials: KJ
authors.lastname: Neufeld
authors.affiliation: Department of Surgery, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Mandal
authors.affiliation: Department of Neurology, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Rebecca F
authors.initials: RF
authors.lastname: Gottesman
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, John Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Hogue
mesh_terms: D000368:Aged; D001921:Brain / Q000503:physiopathology*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D003693:Delirium / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology
keywords: cardiac surgery; postoperative delirium; sulcal width; ventricular size; white matter hyperintensities