Cool down the inflammation: Hypothermia as a therapeutic strategy for acute brain injuries

While hypothermia has historically been appreciated as a possible cause of injury and mortality, its role as a therapeutic agent of choice in special circumstances has been less delineated in its origins. There are reports of ancient Egyptians, Greeks, and Romans possibly implementing it, including Hippocrates specifically recommending that wounded soldiers be surrounded by snow to improve survival (Polderman, Intensive Care Med 30:757-769, 2004). The first clinical usages of hypothermia for brain injury were conducted by the neurosurgeon Temple Fay in the 1930s with subsequent pioneering reports of its therapeutic usage in various brain disorders (Fay, Ann Surg 101:76-132, 1959; Harris et al., Arch Neurol 59:1077-1083, 2002). Over the last few decades, there have been various animal studies and clinical trials that have investigated the various indications and mechanisms of therapeutic hypothermia, many of which implicate a role in curtailing the inflammatory cascade. Only over the past decade, in the setting of adult and pediatric post-anoxic encephalopathy, has hypothermia become an evidence-based therapy. Indications for treatment as well as mitigation of the inflammatory processes in other acute brain injuries such as ischemic and hemorrhagic strokes, traumatic brain injury, and status epilepticus remain controversial. This chapter reviews the role of therapeutic hypothermia, how "cooling the inflammation" may or may not be indicated in a variety of acute brain injuries: Ischemic stroke, neonatal hypoxia-ischemia, post-cardiac arrest global ischemia, traumatic brain injury, intracerebral hemorrhage, subarachnoid hemorrhage, status epilepticus, meningitis/ encephalitis, and acute liver failure.