The pathophysiologic basis of hepatic encephalopathy: central role for ammonia and inflammation

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome associated with both acute and chronic liver dysfunction. It defines prognosis in acute liver injury in which patients can succumb with brain oedema and intracranial hypertension. In cirrhosis, it occurs insidiously, causing a range of neuropsychiatric disturbances. For over a century, we have known that ammonia is important in its pathogenesis and astrocytes are the cells that have been most commonly found to be affected neuropathologically. In this review we centre on the story of the ‘sick astrocyte’, focusing on the molecular pathogenesis of HE and the important role that inflammation has on its modulation. We describe new developments in this area with respect to potential targets for future therapies.