Causes of delirium especially likely to be missed
| Insult | Presentation | How to detect |
|---|---|---|
| Modest insults in context of vulnerable brain | Hypoactive, hyperactive or mixed delirium | Core features of delirium; presence of vulnerability factors (eg dementia, brain injury) |
| Non-convulsive status | Episodic confusion with sudden onset | EEG; history of epilepsy; vigilance to motor symptoms |
| Alcohol withdrawal/delirium tremens | Hyperactive delirium; sympathetic activation (tachycardia, sweating etc); visual hallucinations | Alcohol history; abnormal LFTs/MCV |
| Wernicke’s encephalopathy | Can occur in absence of alcohol withdrawal; ophthalmoplegia or ataxia might be present | Characteristic MRI changes (diencephalic hyperintensities on T2-weighted MRI) specific but not sensitive; response to Pabrinex® |
| Benzodiazepine or other sedative withdrawal | Similar to alcohol withdrawal | History of sedative abuse |
| Medication adverse effects | Very common precipitant. Can present as sedated, but delirium can take various forms. Visual hallucinations can be particularly common with anticholinergic drugs | Be particularly vigilant for medications with anticholinergic effects and opiates |
| Recreational drug intoxication | Depends on actions of drug: nystagmus common, stimulants likely associated with sympathomimetic effects and hyperactive delirium | Drug screen, but will not detect novel psychoactive substances; collateral history |
| Constipation and/or faecal impaction | May be no overt symptoms; abdominal pain | Nursing records of bowel movements; abdominal and PR examination; abdominal X-ray |
| Sleep deprivation | History of sleep disorder (eg sleep apnoea) | History of disturbed sleep; polysomnography (sleep study) |
EEG = electroencephalography; LFTs = liver function tests; MCV = mean corpuscular volume; MRI = magnetic resonance imaging; PR = per rectal