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Hepatic encephalopathy

 

Common precipitants of hepatic encephalopathy

  • Renal failure
  • Gastrointestinal bleeding
  • Infection
  • Constipation
  • Sedative drugs e.g. opiates, benzodiazepines, antidepressantsand antipsychotic drugs
  • Diuretics
  • High protein intake

 

Presentation of hepatic encephalopathy

Can be graded 0-4 or simply defined as mild or severe:

 

  • Grade 0: subclinical; normal mental status, but minimal changes in memory, concentration, intellectual function, coordination.
  • Grade 1: mild confusion, euphoria or depression, decreased attention, slowing of ability to perform mental tasks, irritability, disorder of sleep pattern such as inverted sleep cycle.
  • Grade 2: drowsiness, lethargy, gross deficits in ability to perform mental tasks, obvious personality changes, inappropriate behaviour, intermittent disorientation.
  • Grade 3: somnolent but rousable, unable to perform mental tasks, disorientation to time and place, marked confusion, amnesia, occasional fits of rage, speech is present but incomprehensible.
  • Grade 4: coma, with or without response to painful stimuli.

 

 

OR

  • Mild
    • Impairment of attention and decision-making, and may have impaired fitness to drive. These patients usually have normal function on standard mental state testing but abnormal psychometric testing.
  • Moderate
    • Confusion
    • Asterixis
    • Fetor hepaticus
    • Hypothermia
    • Hyperventilation

 


Video on the pathophysiology of hepatic encephalopathy

 

Investigations in hepatic encephalopathy

  • Full septic screen
  • Ascitic tap to check for SBP
  • Digital rectal exam (DRE) to check for faecal impaction
  • Ammonia levels are raised and can help with diagnosis. The sample needs to be collected and then stored on ice and sent directly to the laboratory.
  • EEG
    • High-amplitude low-frequency waves and triphasic waves – not specific for hepatic encephalopathy.
  • MRI/CT can help to exclude other causes of altered mental function such as intracranial lesions
  • Visual evoked responses show classic patterns associated with hepatic encephalopathy.

 

 Management of hepatic encephalopathy

  • Laxatives (e.g. lactulose) or enemas
    • To clear the nitrogen load
  • Antibiotics
    • To stop nitrogen breakdown
      • Metronidazole 500mg po TDS or 400mg iv TDS
    • Prophylactic antibiotics
      • Rifaximin 550mg twice daily is licensed for prevention of hepatic encephalopathy

 

Click here to download free teaching notes on decompensated liver disease: Hepatic encephalopathy

Perfect revision for medical students, finals, OSCEs and MRCP PACES