The Association of Brain MRI Characteristics and Postoperative Delirium in Cardiac Surgery Patients

Abstract

Purpose Delirium is common after cardiac surgery, and it is associated with short- and long-term consequences, including cognitive decline. Identification of patients who are vulnerable to delirium might allow for early implementation of delirium-prevention strategies in older adults undergoing surgery. 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. Findings 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. Implications 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.

Cotard Syndrome in Hypoactive Delirium – A Case Report

“…Two recent MRI studies could show neither a significant association between brain atrophy or whitematter hyperintensities (Cavallari et al 2015), nor between global or voxel-wise cerebral blood flow, with the incidence and severity of postoperative delirium (Hshieh et al 2016) in nondemented elderly patients. These findings contrast with previous assumptions about neuroradiological risk factors for delirium (Brown et al 2015, Soiza et al 2008). In another study, the correlations of blood oxygen levels between various brain regions in resting-state fMRI scans of patients both during the acute episode and after its resolution were examined (Choi et al 2012).…”

Patients prone for postoperative delirium

“…ApoE4, a marker of Alzheimer's disease, was no risk factor in surgical patients [31,32]. One study group found brain atrophy not to be associated with incidence of POD [33], whereas others identified decreased grey matter volume or cerebral atrophy contributing to POD [34,35].…”

A systematic review of neuroimaging in delirium: predictors, correlates and consequences

“…Another study assessed WMHs after cardiothoracic surgery and demonstrated a trend towards association with post‐operative delirium ( N = 79; WMH 10‐point scale: 3 vs. 2; p = 0.05; Brown et al, ).…”

“…Five studies assessed the relationship between cerebral atrophy and delirium involving 846 patients of whom 175 had delirium. One study (Brown et al, ) used a validated 10‐point rating scale for assessment of cerebral ventricular size and sulcal widening (Manolio et al, ). A validated stroke‐specific 4‐point visual scale (Pasquier et al, ) grading regional sulcal and ventricular atrophy was used in another study (Oldenbeuving et al, ).…”

“…Patients with delirium post‐cardiothoracic surgery had larger ventricular atrophy scores than non‐delirium patients after surgery ( N = 79; median 4 vs. 3; p = 0.003; Brown et al, ) and severe sulcal atrophy and ventricular dilatation predicted delirium following stroke (N = 527; OR 2.7, 95%CI: 1.1–6.8; Oldenbeuving et al, ).…”