Encephalopathy and cerebral edema in the setting of acute liver failure: pathogenesis and management.

Cerebral edema is a potential life-threatening complication in patients with acute liver failure who progress to grade III/IV encephalopathy. The incidence is variably reported but appears to be most prevalent in those patients with hyperacute liver failure as opposed to subacute forms of liver failure. In those patients who are deemed at risk of cerebral edema and raised intracranial pressure, insertion of an intra-cranial pressure monitoring device may be considered to optimize treatment and interventions. The pathogenesis of cerebral edema in this setting remains controversial, although recent work suggests a pivotal role for arterial ammonia, whose effects appear to be potentiated by the presence of systemic inflammation. Recent work has also suggested the import of free radical formation occurring at a mitochondrial level as being the potential mediator of cellular dysfunction as opposed to ammonia per se. Treatment of such patients requires a multi-disciplinary approach incorporating both hepatology and critical care. In a significant proportion of such cases, consideration of liver transplantation may be required. Treatment should be focused at optimizing liver function and regenerative capacity and minimizing the inflammatory milieu. Controlled studies are lacking and much of the management has been extrapolated from neurocritical care. Sustained elevation of intracranial pressure may be responsive to mannitol or hypertonic saline bolus, and in those with hyperemia indomethacin has been reported as beneficial in case series. Recently, interest has developed into the use of cooling in the management of patients with acute liver failure and raised intracranial pressure. Animal studies support this treatment option as do case series, although randomized trials are still awaited.