Unlike dementia, delirium has an acute onset, motor signs (tremor, myoclonus, asterixis), slurred speech, altered consciousness (hyperalert/agitated or lethargic, or fluctuations), hallucinations may be florid.
Consultation-liaison psychiatry could improve the recognition rate of postoperative delirium in elderly patients, and shorten hospitalization time. The training of mental health knowledge for non-psychiatrists could improve the ability of early identify and treatment of delirium 1).
It is a corollary of the criteria that a diagnosis of delirium usually cannot be made without a previous assessment, or knowledge, of the affected person’s baseline level of cognitive function. In other words, a mentally disabled person who is suffering from this will be operating at their own baseline level of mental ability and would be expected to appear delirious without a baseline mental functional status against which to compare.
Confusion Assessment Method for the Intensive Care Unit
Early detection is crucial because the longer a patient experiences delirium the worse it becomes and the harder it is to treat. Currently, identification is through intermittent clinical assessment using standardized tools, like the Confusion Assessment Method for the Intensive Care Unit. Such tools work well in clinical research but do not translate well into clinical practice because they are subjective, intermittent, and have low sensitivity. As such, healthcare providers using these tools fail to recognize delirium symptoms as much as 80% of the time.
EEG shows pronounced diffuse slowing.
Delirium-related biochemical derangement leads to electrical changes in electroencephalographic (EEG) patterns followed by behavioral signs and symptoms. However, continuous EEG monitoring is not feasible due to the cost and the need for skilled interpretation. Studies using limited-lead EEG show large differences between patients with and without delirium while discriminating delirium from other causes. The Ceribell is a limited-lead device that analyzes EEG. If it is capable of detecting delirium, it would provide an objective physiological monitor to identify delirium before symptom onset. This pilot study was designed to explore relationships between Ceribell and delirium status. Completion of this study will provide a foundation for further research regarding delirium status using the Ceribell data 2).
Hut SC, Dijkstra-Kersten SM, Numan T, Henriquez NR, Teunissen NW, van den Boogaard M, Leijten FS, Slooter AJ. EEG and clinical assessment in delirium and acute encephalopathy. Psychiatry Clin Neurosci. 2021 May 16. doi: 10.1111/pcn.13225. Epub ahead of print. PMID: 33993579.
Older age, headache, coagulopathy, decreased level of consciousness, seizures, and history of falls. Conversely, infection was associated with a reduced yield.
In higher-risk patients and settings, there should be a push toward earlier neuroimaging as indicated by clinical examinations and individual risk factors. In the meta-analysis, the yield of head CT was higher in ICU patients and those who had focal neurological deficits in addition to altered mental status and was especially high in neuro ICU settings 4)
Neuroimaging should not replace a clinical exam, even in ICU settings; ICU patients should have their sedation reduced to properly test for delirium 5).
Delirium has a complex and fluctuating course with underlying causes that are often multifactorial; identifying a CNS lesion does not necessarily exclude other causes, and vice-versa 6).
The risks of neuroimaging need to be considered in the decision-making process 7).
The use of CT head to diagnose the etiology of delirium and AMS varied widely and yield has declined. Guidelines and clinical decision support tools could increase the appropriate use of CT head in the diagnostic etiology of delirium/AMS 8).