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:
- 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.
- 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.