Neuroimaging
Neuroimaging provides an important avenue to explore the mechanisms that are responsible for delirium. Despite progress in the development of magnetic resonance imaging (MRI), the large variety in imaging-based findings has limited our understanding of the changes in the brain that may be linked to delirium. Some challenges associated with imaging people diagnosed with delirium include participant recruitment and inadequate consideration of important confounding factors such as history of dementia and/or depression, which are known to be associated with overlapping changes in the brain also observed on MRI.Evidence for changes in structural and functional markers include: changes in white-matter integrity (white matter lesions), decreases in brain volume (likely as a result of tissue atrophy), abnormal functional connectivity of brain regions responsible for normal processing of executive function, sensory processing, attention, emotional regulation, memory, and orientation, differences in autoregulation of the vascular vessels in the brain, reduction in cerebral blood flow and possible changes in brain metabolism (including cerebral tissue oxygenation and glucose hypometabolism). Altogether, these changes in MRI-based measurements invite further investigation of the mechanisms that may underlie delirium, as a potential avenue to improve clinical management of people with this condition. Neurophysiology
Electroencephalography (EEG) allows for continuous capture of global brain function and brain connectivity, and is useful in understanding real-time physiologic changes during delirium.
In the ICU, international guidelines recommend that every patient gets checked for delirium every day (usually twice or more a day) using a validated clinical tool. The definition of delirium that healthcare professionals use at the bedside is whether or not a patient can pay attention and follow simple commands. The two most widely used are the Confusion Assessment Method for the ICU (CAM-ICU) and the Intensive Care Delirium Screening Checklist (ICDSC). Translations of these tools exist in over 20 languages and are used ICUs globally with instructional videos and implementation tips available.More emphasis is placed on regular screening over the choice of tool used. This, coupled with proper documentation and informed awareness by the healthcare team, can affect clinical outcomes. Without using one of these tools, 75% of ICU delirium can be missed by the healthcare team, leaving the patient without any likely interventions to help reduce the duration of delirium. Differential diagnosis
There are conditions that might have similar clinical presentations to those seen in delirium. These include dementia, depression, psychosis, and other conditions that affect cognitive function. Dementia: This group of disorders is acquired (non-congenital) with usually irreversible cognitive and psychosocial functional decline. Dementia usually results from an identifiable degenerative brain disease (e.g. Alzheimer disease or Huntingtons disease), requires chronic impairment (versus acute onset in delirium), and is typically not associated with changes in level of consciousness. Dementia is different from delirium in that dementia lasts long-term while delirium lasts short-term. Depression: Similar symptoms exist between depression and delirium (especially the hypoactive subtype).