Neurology >

“Acute or subacute brain failure in which impairment of attention is accompanied by abnormalities of perception and mood”

Risk Factors
  • Disease – Dementia, constipation, pneumonia, UTI
  • Post-surgical complications – medication e.g. benzodiazepines
  • Altered metabolic homeostasis
    Extremes of age
  • Injured brain – previous head injury, alcohol brain damage, previous stroke
  • Dislocation to an unfamiliar environment e.g. hospital admission
  • Sleep deprivation
  • Sensory extremes
  • Immobilization
  • Systemic infection – particularly with high fever
  • Metabolic disturbance – hepatic failure, CKD, dehydration, hypoxia
  • Vitamin deficiency – thiamine, nicotinic acid, B12
  • Endocrine disease – hypothyroidism, Cushing syndrome
  • Intracranial causes – trauma, tumours, abscess, subarachnoid haemorrhage, epilepsy
  • Drug intoxication – anticonvulsants, antimuscarinics, anxiolytics, TCAs, dopamine agonists, digoxin
  • Drug/alcohol withdrawal
  • Poorly understood
Clinical Presentation
  • Difficulties with attention span, concentration, remaining conscious
  • The patient usually has a reversed sleep cycle i.e. awake in the night, sleeps in the day
  • Disorganised or delayed thinking
  • Can present as hypoactive or hyperactive symptoms
    • HYPERactive: agitated, aggressive, delusions/hallucinations (tactile/visual)
    • HYPOactive: drowsy, less reactive, withdrawn
    • Disordered thinking
    • Euphoric/fearful/depressed/angry
    • Language impaired
    • Illusions/delusions/hallucinations
    • Reversal of sleep/wake cycle
    • Inattention
    • Unaware/disoriented
    • Memory deficits
  • Find the cause!
  • Bloods:
    • FBC
    • U + Es
    • LFTs
    • Blood glucose
    • ABG
    • Septic screen
    • Malaria films
  • Imaging:
    • ECG
    • CT/MRI
  • Special:
    • LP
    • EEG
  • Diagnostic criteria
    • Disturbance of consciousness
    • Change in cognition
    • Develops in hours to days
    • Fluctuation over the course of the day
  • Treat underlying cause.
  • General management:
    • Nurse in moderately lit, quiet room and aim to reduce confusion as much as possible (e.g. same staff, ensure the patient has hearing/visual aids if necessary, place clock in the room to ensure they are oriented with time)
    • Try to get patient to care for themselves
    • Minimize sedatives
  • Brain recovery usually lags behind recovery from the physical illness
  • Anxiety
  • Primary mental illness (e.g. schizophrenia)
  • Dementia

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