Zeldetz, Vladimir

Delirium is a serious neuropsychiatric condition marked by acute confusion and cognitive decline, commonly affecting postoperative and critically ill patients. It is especially prevalent in older adults and those requiring intensive care, including patients undergoing major surgery or receiving mechanical ventilation. For anesthesiologists, delirium is a critical and often underrecognized postoperative complication with complex perioperative contributors. Intensive care unit patients with delirium face increased mortality, cognitive impairment, and persistent symptoms beyond discharge. Despite its clinical significance, the pathophysiology of delirium remains poorly understood, with no standardized classification or targeted therapy. In light of emerging evidence connecting blood–brain barrier (BBB) permeability to the onset of delirium, we found that BBB dysfunction may represent a key mechanism underlying its pathophysiology. Through a thorough examination of predisposing and precipitating factors that impair both BBB integrity and cognitive function, we identified many points of connection between BBB dysfunction and delirium specifically. We include here a summary of our diagnostic approach with the aim of improving therapeutic strategies based on preserving BBB function to prevent or mitigate delirium.

Diffuse axonal brain injury (DAI) is a common, debilitating consequence of traumatic brain injury, yet its detection and severity grading remain challenging in clinical and experimental settings. This study evaluated the sensitivity of diffusion tensor imaging (DTI), histology, and neurological severity scoring (NSS) in assessing injury severity in a rat model of isolated DAI. A rotational injury model induced mild, moderate, or severe DAI in male and female rats. Neurological deficits were assessed 48 h after injury via NSS. Magnetic resonance imaging, including DTI metrics, such as fractional anisotropy (FA), relative anisotropy (RA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD), was performed prior to tissue collection. Histological analysis used beta amyloid precursor protein immunohistochemistry. Sensitivity and variability of each method were compared across brain regions and the whole brain. Histology was the most sensitive method, requiring very small groups to detect differences. Anisotropy-based MRI metrics, especially whole-brain FA and RA, showed strong correlations with histology and NSS and demonstrated high sensitivity with low variability. NSS identified injury but required larger group sizes. Diffusivity-based MRI metrics, particularly RD, were less sensitive and more variable. Whole-brain FA and RA were the most sensitive MRI measures of DAI severity and were comparable to histology in moderate and severe groups. These findings support combining NSS and anisotropy-based DTI for non-terminal DAI assessment in preclinical studies.