Exploring Postoperative Cognitive Dysfunction and Delirium in Noncardiac Surgery Using MRI: A Systematic Review.

Chenxi Huang,Johan Mårtensson,Mohammad Sohail Asghar,Ismail Gögenur

doi:10.1155/2018/1281657

Abstract

Surgical patients are at high risk of developing postoperative cognitive dysfunction (POCD) and postoperative delirium (POD). POCD and POD are associated with increased morbidity and mortality and worsening functional outcomes leading to severe socioeconomic consequences for the patient and the society in general. Magnetic resonance imaging (MRI) offers a unique opportunity to study the anatomy and function of the brain. MRI thus plays an important role in elucidating the neuronal component of POCD and POD. Our aim has been to systematically gather MRI findings that are related to POCD and POD. Systematic searches were conducted in PubMed, EMBASE, and PsycINFO: MRI studies investigating patients with POCD as identified by perioperative cognitive testing or patients with delirium identified postoperatively by the Confusion Assessment Method. A total of ten eligible papers were included with a total of 269 surgical patients, 36 patient controls, and 55 healthy controls who all underwent MRI examination. These studies suggested that reduction of thalamic and hippocampal volumes and reduction of cerebral blood flow may be associated with POCD, while presurgery/preexisting and postoperative white matter pathology may be associated with POD. However, the evidence from these studies is rather weak. Future MRI studies are warranted to verify the current findings.

Highlights

A quarter billion major surgical procedures are performed every year worldwide [1]
We have predefined that for studies to be eligible for inclusion they had to fulfill the following criteria: (i) With regard to postoperative cognitive dysfunction (POCD) studies, pre- and/ or postsurgery neuropsychological testing of attention, memory, or executive functions should have been performed within 30 days of surgery, (ii) with regard to delirium studies, delirium identified within 30 days of surgery by Confusion Assessment Method (CAM) or validated CAM based delirium screening tools (e.g. 3D CAM and CAM-intensive care unit (ICU)), and (iii) all studies should contain a population that have undergone surgery prior to the occurrence of POCD or postoperative delirium (POD)
The studies indicated that reduced volume of the thalamus, reduced volume of the hippocampus, preexisting degenerative white matter pathology or reduced cerebral blood flow (CBF) may be correlated with POCD

Summary

Introduction

A quarter billion major surgical procedures are performed every year worldwide [1]. Cognitive impairment arising after surgical intervention is referred to as postoperative cognitive dysfunction (POCD) and is a common adverse event to surgery. The manifestations of POCD may be subtle and diverse, depending on which cognitive domain that is affected. It is well established that cardiac surgery can cause transient or permanent POCD [3, 4]. POCD can occur after any kind of surgery [5, 6]. A larger multicenter study showed that 25.8% of noncardiac surgical patients suffered from POCD one week after the surgery, and 40% of these patients had persisting cognitive dysfunction three months after surgery [5]. POCD may subsequently lead to mild cognitive impairment and dementia even in patients who have recovered from the initial cognitive decline [8, 9]

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Discussion

Conclusion