Hepatic encepahalopathy is a neuropsychiatric syndrome with multiple manifestations. It is caused by liver failure and / or portosystemic shunting of blood. It is potentially reversible.
Loss of function / or mass of hepatocytes can cause hepatic encephalopathy. The former occurs in acute fatty liver of pregnancy.
Pathogenesis of hepatic encephalopathy
Various agents are implicated in the pathogenesis of hepatic encephalopathy:
Direct ammonia toxicity
Mercaptan, short chain fatty acids
Aromatic amino acids
Types of hepatic encephalopathy
1. Acute liver failure
2. Major portosystemic shunt without cirrhosis as in non-cirrhotic portal hypertension
3. Chronic liver disease
Overt vs minimal hepatic encephalopathy
Overt hepatic encephalopathy: Altered consciousness, asterixis, hyper-reflexia, rigidity, altered sleep rhythm, fetor hepaticus
Minimal hepatic encephalopathy: It is not obvious and is detected only by tests like number connection tests or neuro imaging. It is important to be checked in pilots, drivers etc with chronic liver disease as it can affect critical decesion making with catastrophic results.
Precipitating factors for hepatic encephalopathy
Gastro-intestinal hemorrhage, sepsis, electrolyte imbalance, sedatives, alcoholic binge, hepatocellular carcinoma
It is important to exclude other causes of encephalopathy and serum ammonia level estimation may help in excluding a diagnosis of hepatic encephalopathy in such situations.
Empiric treatment of hepatic encephalopathy
Gut cleansing with bowel wash etc.
Low protein diet
Lactulose / Lactitol
Bowel sterilization with neomycin / metronidazole
Probiotics may have a role
In acute liver failure, there is deeper coma, cerebral edema and a worse outcome.
Liver transplantation is probably the only final answer.