Abstract
Wijdicks EFM. N Engl J Med. Epub ahead of print 27 October 2016. DOI: 10.1056/NEJMra1600561.
If a cirrhotic liver fails acutely, delirium can ensue. Acute liver failure in a previously healthy organ can cause cerebral oedema, which can fatally compromise brain-stem function.
Severe encephalopathy in the cirrhotic patient confers a mortality of >50% in year 1. Usually, ammonia is catabolized via the urea cycle – it accumulates in liver failure. Brain swelling particularly occurs when ammonia rises quickly. Astrocyte glutamine synthase converts ammonia and glutamate into glutamine. Due to the latter’s osmotic effect, brain volume rises: risk increases with ammonia >200 µmol/L.
Early reduced awareness is typical. As illness progresses, verbal communication is lost; this subgroup often has respiratory alkalosis. Dyskinesias may be detected in Wilson’s, a rare cause of acute liver failure. Differentials include Korsakoff’s, subdural haematoma and alcohol withdrawal, but the regular tremor and cold sweats of the latter are not seen in encephalopathy.
Lactulose reduces absorption of ammonia – adjust dose to achieve three bowel movements daily. The MELD (Model for End-stage Liver Disease) score for disease severity and need for transplant includes serum bilirubin, creatinine and international normalized ratio. In the intensive care unit, mannitol or hypertonic saline is recommended if computerized tomography confirms cerebral oedema. This article is a useful review of a common medical presentation, with a prognosis that remains poor.