Delirium (Acute Confusional State)
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Delirium is defined as an acute and fluctuating disturbance in level of consciousness, attention and global cognition.

  • Prompt treatment is required to avoid potential brain damage.
  • The underlying mechanism is poorly understood, but believed to involve neurotransmitter abnormalities and inflammation.


Delirium occurs most commonly in the elderly and very young.
  • It is predicted that 10% of patients over 65 show signs of delirium on admission to hospital.
  • Affects 15% of in-patients.

Signs and symptoms

  • Reduced level of consciousness;
  • Psychiatric symptoms:
    • Disorientation (time/place/person);
    • Inattention;
    • Illusions/hallucinations;
    • Altered personality;
    • Mood disorders;
    • Speech disorders (slurred speech/aphasic error/chaotic pattern).
  • Lacking insight.
  • These symptoms fluctuate over the course of the day and tend to be worse at night. Patients may show signs of hyperactivity (typically in withdrawal states) or lethargy (common in hepatic encephalopathy).


Stroke, abscess, tumour, subdural haematoma
Drugs (or withdrawal)
Anticholinergics, antiemetics, antipsychotics, corticosteroids, digoxin, levodopa, TCAs, opioids, alcohol
Hyperparathyroidism, hyper/hypothyroidism
Encephalitis, meningitis, pneumonia, sepsis, UTI, burns, hypothermia
Acid-base disturbance, hepatic encephalopathy, uraemia, hypo/hyperglycaemia, electrolyte abnormalities, thiamine/vitamin B12 deficiency
Post-operative states, other mental disorders, sleep depravation


  • A collateral history is needed to determine if the changes in mental status are recent and the patients normal level of functioning.
  • This would be different in a patient with dementia, where the memory problems are more likely to be chronic with a gradual onset. Patients with dementia are also less likely to have inattention or impaired level of consciousness until the later stages of disease.
Delirium Vs. dementia
Sudden onset and fluctuating course over days – weeks
Gradual onset, slowly progressive over months – years
Variation in level of consciousness
Consciousness unimpaired
Impaired attention
Attention preserved
Psychomotor changes
Often normal

It is also important to take a drug history (consider any with CNS effects or new additions as a potential cause) and alcohol history.
A mini-mental state examination is likely to show deficits in attention (e.g. immediate repetition of 3 objects).
Diagnostic tools such as the Confusion Assessment Method (CAM) states that the following features are diagnostic:

  • Acute change in cognition which fluctuates during the day;
  • Inattention;
  • Disturbance of consciousness;
  • Disorganised thinking.

The patient should be examined to look for potential sites of infection or any focal neurological signs (suggesting a structural CNS disorder).


  • Treating the underlying cause or removing aggravating drugs is the principle treatment.
  • Environmental management: nurse patients in a quiet and well-lit room.
  • Minimise sensory deficits (check hearing aids/glasses etc.)
  • Agitation can be managed with haloperidol¬†(0.5-1.0mg PO) or lorazepam (0.5-1.0mg PO), however, they should be avoided as they may worsen or prolong delirium.


  1. Mind disorders ‚Äď Delirium
  2. E-medicine РDelirium
  3. The Merck Manual РDelirium and dementia
  4. BNF

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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