Patients with fulminant hepatic failure (FHF) often develop cerebral edema, high intracranial pressure (ICP)that may result in fatal brain damage. The aim in this protocol is to determine if a rise in the brain concentration of glutamate, lactate and pyruvate are involved in development of surges of high ICP in patients with FHF. The study is observatory in nature and also record the influence of any intervention that may e instituted during the course of the critical illness.