Brain damage following stoke and after successful cardiac resuscitation remains a major cause of morbidity and mortality worldwide. Stroke is the third cause of death in developed countries, ranking only behind cancer and heart disease. Over the last several years animal studies have demonstrated some brain protection by inducing mild brain cooling (32-35° C.). It has been shown that a reduction of the brain temperature by as little as 2° C. may substantially reduce the ischemic damage of the brain. Clinical trails in different patient's populations resulted in conflicting results. In both adults and children that were treated with hypothermia following major traumatic brain injuries there was no evidence of benefit outcome at 6 and 12 months after the injury. On the other hand hypothermia therapy was found to be of benefit in adults and newborns with a hypoxic-ischemic (leak of oxygen and blood supply to the brain) brain injury.
The treating physician has to apply an effective hypothermic therapy as soon as possible, and minimize the neurological injury. There are several approaches to induce hypothermia both invasive and non-invasive. Most of the currently published clinical studies used non-invasive external cooling approach. One approach is to cool the entire body inducing whole body hypothermia. The major drawbacks of this approach are the 1. slow cooling rate due to the large volume of the body 2. The cumbersome of the large devices that were used 3. The possible deleterious systemic effects such as metabolic, cardiovascular, pulmonary, coagulation and immunologic complications. These effects may occur during the hypothermia period as well as during the re warming time. The increased risk of systemic complications when using whole body hypothermia may outweigh the brain protective benefits of such therapy.
Since the human brain weigh is only 2% of the total body weight and it receives 20% of the resting cardiac output it is not necessary to cool the entire body in order to achieve a reduction of the brain temperature. Presently brain cooling devices include surface cooling with ice-packs or cooling helmets and invasive approaches such as naso-phyrayngeal cooling and intra-carotid cold flushes. The cooling time while using these modalities is short (less than 1 h), however it provides more preferential cooling of the superficial areas of the brain that are in adjacent to the cooling device.