Fulminant hepatic failure (FHF) is often complicated by cerebral edema, high intracranial pressure (ICP) and brain death. Accordingly the intracranial pressure is often monitored in such patients in order to be able to institute treatment before high ICP evolves. As routinely done in patients with severe head injury a microdialysis monitoring catheter is also placed under this procedure to measure metabolic changes that are responsible for surges of high ICP. The aim in this descriptive protocol is to determine if a rise in glutamate, lactate and pyruvate concentration in the brain cortex 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 during the course of the critical illness.