Overview
Hepatic encephalopathy (HE) describes the neuropsychiatric signs and symptoms seen due to liver disease. It is mainly a diagnosis of exclusion.
The underlying mechanism is not fully understood, however, it is thought to be due to the build-up of ammonia. Ammonia is produced by intestinal bacteria and is normally converted by the liver into urea, which is less toxic.
Causes
HE is typically by certain precipitants occurring in someone with chronic liver disease but still may occur due to the liver failure itself directly. Some of these precipitants may be:
- Acute kidney injury – due to an inability to excrete urea, which contains nitrogen
- Electrolyte imbalances
- Constipation – due to an inability to excrete urea
- Infection
- High protein – contains more nitrogen leading to more ammonia produced by the gut
Presentation
- Confusion
- Sleep disturbances
- Mood disturbances
- Motor disturbances:
- Ataxia
- Extrapyramidal symptoms (rigidity, bradykinesia, tremors)
Investigations
Initial investigations should involve looking for other potential underlying causes such as:
Severity Grading
HE can be graded according to severity:
- Grade 1 – may have impaired attention
- Grade 2 – may have confusion and personality changes
- Grade 3 – may have more significant confusion and drowsiness
- Grade 4 – coma
Management
Overview
- 1st-line: treat underlying precipitating cause
- For prophylaxis, lactulose and rifaximin can be used:
- Lactulose aids the excretion of ammonia and rifaximin can help to modify the gut flora to reduce ammonia production
Prognosis
- The prognosis of HE depends on the severity of liver disease, the underlying precipitant, and the timing of treatment.
