Method: Patients are randomized to hypothermia- or control-group via randomization envelopes. Patients assigned to receive hypothermia are cooled to a core temperature of 35°C for 12 hours by means of a non-invasive temperature management system and cold i.v. fluids. Induction of hypothermia is initiated within 6 hours of symptom onset. After 12 hours of successful cooling the target temperature is gradually raised to achieve slow re-warming of 0.2°C/h until the core temperature reaches 36.8°C.