Brain autopsy findings in intensive care unit patients previously suffering from delirium: a pilot study

Purpose: Delirium affects 50% to 80% of intensive care unit (ICU) patients and is associated with increased risk of mortality. Given the paucity of data reporting the neuropathologic findings in ICU patients experiencing delirium, the purpose of this pilot, hypothesis-generating study was to evaluate brain autopsies in ICU patients who suffered from delirium to explore possible neuroanatomical correlates.

Materials and methods: Using delirium databases at Vanderbilt University, we identified patients who had delirium in the ICU and subsequently died and received a brain autopsy during the same hospitalization. Brain autopsy reports were collected retrospectively on all 7 patients who met these criteria.

Results: Patients' mean age was 55 (SD ± 8.4) years, and median number of days spent with delirium was 7 (± 5 interquartile range). In 6 (86%) of 7 patients, pathologic lesions normally attributed to hypoxia or ischemia were noted in the hippocampus, pons, and striatum. Hippocampal lesions represented the most common neuropathologic site of injury, present in 5 (71%) of 7 patients.

Conclusions: Hypoxic ischemic injury in multiple locations of the brain was a common finding. The biological plausibility of hippocampal lesions as a contributor to long-term cognitive impairment warrants postmortem investigation on a larger scale with comparison to patients not experiencing ICU delirium.