Abstract:
Acute post-asphyxial encephalopathy around the time of birth remains a major cause of death and disability. The possibility that hypothermia may be able to prevent or lessen asphyxial brain injury is a "dream revisited". In this review, a historical perspective is provided from the first reported use of therapeutic hypothermia for brain injuries in antiquity, to the present day. The first uncontrolled trials of cooling for resuscitation were reported more than 50 years ago. The seminal insight that led to the modern revival of studies of neuroprotection was that after profound asphyxia, many brain cells show initial recovery from the insult during a short "latent" phase, typically lasting approximately 6 h, only to die hours to days later after a "secondary" deterioration characterized by seizures, cytotoxic edema, and progressive failure of cerebral oxidative metabolism. Studies designed around this conceptual framework showed that mild hypothermia initiated as early as possible before the onset of secondary deterioration, and continued for a sufficient duration to allow the secondary deterioration to resolve, is associated with potent, long-lasting neuroprotection. There is now compelling evidence from randomized controlled trials that mild induced hypothermia significantly improves intact survival and neurodevelopmental outcomes to mid-childhood.Moderate to severe hypoxic-ischemic encephalopathy (HIE) continues to be a significant cause of acute neurologic injury at birth, occurring in approximately 1 to 2 cases per 1000 term live births in the developed world (1). The risks are approximately ten-fold higher in the developing world (1). The possibility that hypothermia might be able to prevent or lessen asphyxial brain injury has been raised since antiquity, and so should be seen as a "dream revisited" (2).