Delirium

Impaired consciousness with intrusive abnormalities of perception and affect

Aetiology

  • Most common mental heath problem in hospitalised patients over 65 years

Causes of delirium

  • Drugs e.g. anticholinergic agents, anticonvulsants, alcohol, illicit drugs
  • Withdrawal e.g. alcohol, sedatives (bensodiazapines)
  • Metabolic e.g. hypoglycaemia, deranged fluid/electrolyte balance
  • Infections
  • Head trauma
  • Epilepsy
  • Neoplastic diseases
  • Vascular disorders

Risk factors

  • Age - elderly patients
  • Cognitive deficit - dementia
  • Previous episode
  • Perioperative - long surgery, emergency surgery
  • Extremes in sensory experience - hypo/hyperthermia
  • Existing sensory deficits - deafness/blindness
  • Immobility
  • Social isolation
  • New environment
  • Stress

Clinical presentation

General features

  • Rapid onset
  • Transient and fluctuating course
  • Lasts days-months depending on underlying cause

Hyperactive delirium

  • Elderly (+/- cognitive impairment)
  • Recent injury e.g. fractured hip
  • Sudden onset new confusion, agitation, restlessness
  • Fine during the day
  • Overactive in the evening, awake overnight with disruptive behaviour and delusions/hallucinations of persecution

Hypoactive delirium

  • Elderly (+/- cognitive impairment)
  • Recent injury e.g. fractured hip
  • Becomes suddenly quiet, withdrawn, sleepy
  • Fluctuates through the day
  • Doesn't eat, drink, tend to care
  • Often misdiagnosed as depression

Mixed delirium

  • Most commonly seen
  • Vary wildly throughout a 24hr period
  • Often labeled as 'behavioural'
  • Asleep all day and awake all night with very disruptive behaviours

Investigations

Diagnostic criteria

  • Impairment of consciousness
  • Disturbance of cognition
  • Psychomotor disturbance
  • Disturbance of sleep-wake cycle
  • Emotional disturbance

Formal cognitive tests

  • e.g. MMSE, 4AT, ACE-R

Investigate for underlying cause

  • Urine analysis
  • FBC, U+Es, LFTs
  • Thyroid function
  • Blood glucose
  • CRP
  • B12 and folate
  • CXR
  • MRI/CT brain
  • Consider EEG

Management

  • Identify and treat cause
  • Manage environment and provide support e.g. reality orientation, correct sensory impairments, bright sideroom, 'unsafe' objects removed
  • Review patient frequently
  • Pharmacological therapy
    • Low dose haloperidol
    • Low dose lorazepam - for Parkinson's, lewy body dementia, neuroleptic sensitivity
    • In alcohol/sedative withdrawal, remember regular prescribing of benzodiazepine therafter
    • In delerium of other causes, prescribing of antipsychotic (usually haloperidol) may continue to be necessary
  • Mean duration is 1-4 weeks, often longer than this in the elderly, a minority can become chronic

Complications

  • Undertreatment of recognised cases has an adverse impact on length of stay, morbidity and mortality