Hepatic encephalopathy is a syndrome observed in patients with cirrhosis. Hepatic encephalopathy is defined as a spectrum of neuropsychiatric abnormalities in patients with liver dysfunction, after exclusion of brain disease. It is characterized by personality changes, intellectual impairment, and a depressed level of consciousness.

Subtle signs of hepatic encephalopathy are observed in nearly 70% of patients with cirrhosis. Symptoms may be debilitating in a significant number of patients. Overt hepatic encephalopathy occurs in about 30-45% of patients with cirrhosis. It is observed in 24-53% of patients who undergo portosystemic shunt surgery.
The development of hepatic encephalopathy negatively impacts patient survival. The occurrence of encephalopathy severe enough to lead to hospitalization is associated with a survival probability of 42% at 1 year of follow-up and 23% at 3 years.
Approximately 30% of patients dying of end-stage liver disease experience significant encephalopathy, approaching coma.

Grades of hepatic encephalopathy (West Haven classification system)
Grade 0. Minimal hepatic encephalopathy (previously known as subclinical hepatic encephalopathy). Lack of detectable changes in personality or behavior. Minimal changes in memory, concentration, intellectual function, and coordination. Asterixis is absent.
Grade 1. Trivial lack of awareness. Shortened attention span. Impaired addition or subtraction. Hypersomnia, insomnia, or inversion of sleep pattern. Euphoria, depression, or irritability. Mild confusion. Slowing of ability to perform mental tasks. Asterixis can be detected.
Grade 2. Lethargy or apathy. Disorientation. Inappropriate behavior. Slurred speech. Obvious asterixis. Drowsiness, lethargy, gross deficits in ability to perform mental tasks, obvious personality changes, inappropriate behavior, and intermittent disorientation, usually regarding time.
Grade 3. Somnolent but can be aroused, unable to perform mental tasks, disorientation about time and place, marked confusion, amnesia, occasional fits of rage, present but incomprehensible speech.
Grade 4. Coma with or without response to painful stimuli.

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Adapted from Medscape Drugs & Diseases. Hepatic encephalopathy. Available at http://emedicine.medscape.com/article/186101-overview#a3. Accessed on February 15, 2016. To view the entire article and all other content on the Medscape Drugs & Diseases site, a free, one-time registration is required.