The use of cerebral imaging for investigating delirium aetiology.

BACKGROUND: This study aims to investigate the frequency and patterns of use of cerebral imaging in delirium and to describe pathological changes associated with delirium using computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS: This retrospective observational study included patients with delirium admitted to a tertiary hospital (The Royal Melbourne Hospital, Australia) between January 2015 and August 2016. Data on cerebral imaging was collected and positive imaging findings were defined as: Acute or subacute infarct, haemorrhage, abscess, neoplasm, vasculitis, posterior reversible encephalopathy syndrome, encephalitis, acute demyelination, or fat embolism.

RESULTS: There were 1653 (5% of 32,725) patients with delirium (median age 80 years, inter-quartile range 71-86, 54% male). Thirty-three percent (N = 538) had cerebral imaging (CT only: N = 457, MRI only: N = 10, both: N = 71). In 11% (N = 57) of patients, CT brain scans were positive. MRI brain was completed in 17 patients with a positive CT (17/57), changing the diagnosis in two cases. Fifty-four patients with negative CT scans also had MRI brain; 33% (N = 18) of these were positive. Younger patients were more likely to have MRI compared to CT brain scan. Patients admitted to a neurology unit were more likely to have cerebral imaging.

CONCLUSION: Use of CT brain was common in delirium patients, with an 11% rate of positive findings. Fewer patients had MRI brain scans, which added diagnostic information in some cases. Future studies are needed to define the significance of cerebral imaging in delirium management and establish guidelines for its use.