A Decrease in the Volume of Gray Matter as a Risk Factor for Postoperative Delirium Revealed by an Atlas-based Method.

<bold>Objective: </bold>Delirium is a common syndrome in older patients after surgery. Although an atrophic change in the whole brain may be a potential risk factor for postoperative delirium, the anatomically specific change related to the vulnerability still remains a significant issue.<bold>Design: </bold>Prospective study.<bold>Setting: </bold>University hospital.<bold>Participants: </bold>116 consecutive patients who underwent elective cardiac operations.<bold>Measurements: </bold>Before the surgery, magnetic resonance imaging (MRI) was evaluated. The MRI data were processed to calculate the absolute volumes of the predefined region of interest using Statistical Parametrical Mapping 8 with an atlas-based method. The evaluated volume was expressed as the fraction (%) of the total intracranial volume. Postoperative delirium was diagnosed according to the DSM-IV criteria for delirium.<bold>Results: </bold>Delirium developed in 19 of 116 patients (16.4%) with an age range from 58 to 84 years. Based on a comparison with the age-controlled non-delirium patients (over 57 years; n = 65), a statistically significant reduction in the gray matter volume of the delirium patients was observed in the defined gyri of the temporal and limbic lobes. Moreover, a moderate value (>0.8) of area under the curve to predict postoperative delirium was revealed by receiver operating characteristic curve analysis of the gyri of temporal lobe.<bold>Conclusions: </bold>The decreased volume of gray matter could be associated with the vulnerability to delirium after surgery. The atlas-based method would be a potential tool to pre-screen the brain structure of individual patients for the prediction of postoperative delirium. [ABSTRACT FROM AUTHOR]