Proton Magnetic Resonance Spectroscopy in adult cancer patients with delirium

Structural Brain Changes in Delirium: An Integrative Review

Delirium is a serious complication of acute illness. Little is known, however, regarding the neurobiology of delirium, largely due to challenges in studying the complex inpatient population. Neuroimaging is one noninvasive method that can be used to study structural and functional brain abnormalities associated with delirium. The purpose of this integrative literature review was to examine the content and quality of current structural neuroimaging evidence in delirium. After meeting inclusion criteria, 11 articles were included in the review. Commonly noted structural abnormalities were impaired white matter integrity, brain atrophy, ischemic lesions, edema, and inflammation. Findings demonstrated widespread alterations in several brain structures. Limitations of the studies in this review included small sample sizes, inappropriate or questionable delirium measurements, and failure to consider confounding variables. This review provides insight into possible structural changes responsible for the signs and symptoms seen in patients with delirium, but more high-quality studies are needed.

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

OBJECTIVE

Neuroimaging advances our understanding of delirium pathophysiology and its consequences. A previous systematic review identified 12 studies (total participants N = 764, delirium cases N = 194; years 1989-2007) and found associations with white matter hyperintensities (WMH) and cerebral atrophy. Our objectives were to perform an updated systematic review of neuroimaging studies in delirium published since January 2006 and summarise the available literature on predictors, correlates or outcomes.

METHODS

Studies were identified by keyword and MeSH-based electronic searches of EMBASE, MEDLINE and PsycINFO combining terms for neuroimaging, brain structure and delirium. We included neuroimaging studies of delirium in adults using validated delirium assessment methods.

RESULTS

Thirty-two studies (total N = 3187, delirium N = 1086) met the inclusion criteria. Imaging included magnetic resonance imaging (MRI; N = 9), computed tomography (N = 4), diffusion tensor imaging (N = 3), transcranial Doppler (N = 5), near infrared spectroscopy (N = 5), functional-MRI (N = 2), single photon emission computed tomography (N = 1), proton MRI spectroscopy (N = 1), arterial spin-labelling MRI (N = 1) and 2-¹³ fluoro-2-deoxyglucose positron emission tomography (N = 1). Despite heterogeneity in study design, delirium was associated with WMH, lower brain volume, atrophy, dysconnectivity, impaired cerebral autoregulation, reduced blood flow and cerebral oxygenation and glucose hypometabolism. There was evidence of long-term brain changes following intensive care unit delirium.

CONCLUSIONS

Neuroimaging is now used more widely in delirium research due to advances in technology. However, imaging delirious patients presents challenges leading to methodological limitations and restricted generalisability. The findings that atrophy and WMH burden predict delirium replicates findings from the original review, while advanced techniques have identified other substrates and mechanisms that warrant further investigation.

The impact of intra- and postoperative albumin levels as a biomarker of delirium after cardiopulmonary bypass: results of an exploratory study

In this prospective study the frequency of delirium after cardiac surgery with cardiopulmonary bypass (CPB) was determined. Furthermore, we investigated the impact of intra- and postoperative levels of albumin as a biomarker of delirium. Thirty-four patients who underwent elective CPB at the Department of Cardiac Surgery, Ludwig-Maximilians-University of Munich, Germany, were enroled in this prospective study. During the intensive care unit (ICU) stay and shortly after discharge from the ICU, delirious state was evaluated daily using the Delirium-Rating-Scale. Albumin was assayed pre-anaesthesia, immediately after induction of anaesthesia, at the beginning of the heart-lung-apparatus period, immediately before the opening and 5min after the opening of the aortic clamp, 24h and 48h postoperatively and on the day before discharge. After CPB, a clinical significant delirious state was observed in 11 patients (32.4%). The albumin level decreased during the surgical intervention and increased postoperatively with a maximum level at the time of discharge. CPB patients with delirious state showed a significantly lower albumin level 24h and 48h postoperatively than those without delirium. A low level of postoperative albumin seems to be a useful biomarker to identify patients with high risk of delirious state after CPB.