The use of surface cooling and brief circulatory arrest in the repair of previously inoperable cardiac anomalies awakened modern scientific interest in hypothermia less than two decades ago. Oxygen consumption in the dog and man is approximately halved by every 8 C decrease in body temperature.1,2 With body temperature lowered to 30 C cardiac arrest can be tolerated for 10 minutes. This allows a brief period of bloodless neurosurgery or cardiovascular surgery but is usually insufficient to deal with difficult problems such as multiple or broad based cerebral arterial aneurysms, rupture of a berry aneurysm during surgery or carotid artery reconstruction. Therefore, some clinics have used deep general hypothermia in the range of 15 C for difficult neurosurgical procedures.3,4 This has required supportive cardiopulmonary bypass. An alternate technique combines moderate surface-induced hypothermia with profound selective cerebral hypothermia. This avoids the use of bypass and the complications of profound