Objectives: The prediction of delirium is important because early intervention reduces the duration of delirium and its complications. We reported some neural risk factors such as prefrontal and caudate dysfunction in a previous study without correcting for the level of cognitive dysfunctions. The present study aimed to investigate predictive neural correlates of postoperative delirium after correcting for cognitive level. 

Methods: Before surgery, 57 patients with hip fracture were assessed for cognitive impairment and scanned using magnetic resonance imaging. After surgery, they were evaluated for postoperative delirium for 7 successive days. Then anatomical and functional data were analyzed with voxel-based morphometry and seed-based functional connectivity analysis. 

Results: Patients with postoperative delirium, compared with patients without postoperative delirium, showed decreased gray matter volume in the medial prefrontal cortex, precuneus, superior and transverse temporal gyri, and caudate nucleus. In functional connectivity, patients with postoperative delirium showed increased connectivity between the medial prefrontal cortex and precuneus and between the transverse temporal gyrus and precentral gyrus, and decreased connectivity between the superior temporal gyrus and superior frontal gyrus and between the transverse temporal gyrus and middle occipital gyrus.

Conclusion: Conclusion: GM density in the caudate/suprachiasmatic nucleus was suggested be an important neural predisposing factor for postoperative delirium in a previous study. To exclude the involvement of dementia in postoperative delirium occurrence, scores for cognitive impairments were used as covariate on voxel based morphometry. Based on this study, brain regions other than the caudate nucleus were identified that may predispose individuals to develop delirium appear to be the supplementary motor area, precuneus, temporal pole, transverse temporal gyrus, and the superior temporal gyrus. Furthermore, two sets of brain regions showed increased functional connectivity—one connectivity may be associated with improved capacity to recover from pathological mental state and the other may be associated with greater vulnerability to develop delirium.

Investigation of the neural risk factors for postoperative delirium using magnetic resonance imaging