40. Liver failure - hepatic encephalopathy and coma
Explains hepatic encephalopathy, a neuropsychiatric syndrome from liver failure, ranging from mild confusion to coma. Covers endogenous and exogenous causes, ammonia accumulation and portosystemic shunting, early signs such as asterixis, progression to coma, and diagnosis via clinical features, EEG and blood ammonia. Treatment with lactulose, supportive care and transplantation is followed by complications including renal failure and spontaneous bacterial peritonitis.
Topic 38 of 58 in the MU Sofia syllabus for Internal Medicine (Theory) (Medicine, Year 3). The free AceMed note covers it in 8 sections, about 478 words (3 min of reading), with 14 flashcards.
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Liver Failure- Hepatic Encephalopathy and Coma
Definition:
Etiology:
Pathogenesis:
Symptoms:
Diagnosis:
Treatment:
Complications:
Definition:
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome resulting from liver failure. It is characterized by a range of neurological disturbances, from mild confusion to deep coma, and is commonly seen in end-stage liver disease or acute liver failure. It is also known as portosystemic encephalopathy (PSE).
Etiology:
Hepatic encephalopathy can be caused by:
1. Endogenic (Internal):
Acute infections (e.g., viral hepatitis)
Toxicity, especially in fulminant acute viral hepatitis or chronic liver disease
Decreased detoxification capacity of the liver, leading to accumulation of neurotoxins such as:
Ammonia: Normally, ammonia is converted to urea by the liver for excretion. In liver failure, ammonia accumulates and enters the bloodstream, bypassing detoxification processes.
Fatty acids and mercaptans: Other toxins may contribute to the pathogenesis.
2. Exogenic (External):
Exposure to toxins, including certain medications (e.g., sedatives), gastrointestinal bleeding, electrolyte imbalances, or infection.
Portosystemic shunting: The liver bypasses the usual detoxifying process through shunts, allowing toxins like ammonia to directly enter systemic circulation.
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