An intriguing study from the Children’s Hospital in Los Angeles puts forth the idea that newborns experiencing hypoxic-ischemic encephalopathy (HIE) could be given therapeutic hypothermia to protect the brain.
HIE is a specific form of brain damage that happens when a newborn’s brain is deprived of oxygen (hypoxia) combined with low blood flow (ischemia). It’s considered a type of injury in which the start of the deprivation is often the period immediately before or after delivery. Without immediate treatment, death is likely. However, even with intervention, there are lingering complications, such as cerebral palsy, epilepsy, or development delays. HIE affects two percent of every live full-term birth, with premature babies being more susceptible.
To understand the effects that therapeutic hypothermia—the targeted cooling of the brain—has on infants, MRI scans were performed on 31 infants with HIE. The scans were run both during and after the hypothermia treatment. This enabled the mapping of the biochemical processes in the brain during the procedure.
The researchers found that a neuroprotective effect was achieved when the brain was cooled enough to create a careful balance between energy metabolism and neurotransmission. This is somewhat paradoxical, since the hypothermia employed in this instance is slowing the brain, while it is attempting to heal itself. Other medical uses of hypothermia, such as during heart surgery, only slow the brain during vulnerable periods, rather than after an injury has already occurred.
One possible explanation, according to study researchers, is the reduction in neurotransmitters during therapeutic hypothermia. Neurotransmitters consume up to half of the brain’s energy, so slowing this production greatly reduces the brain’s “hunger.” Without as large of an “appetite,” the brain cannot be starved as easily. If the results of the study are confirmed, therapeutic hypothermia could be more commonly employed alongside regular HIE treatments.
HIE can be caused by different factors including complications during delivery, trauma, congenital defects, cardiac or pulmonary disease, preeclampsia, and abnormal fetal position, among others. The exact treatment option varies depending on cause, but they all revolve around protecting the organs and restoring oxygen to the brain. This can include mechanical ventilation, hyperbaric oxygen treatment, anesthesia (in case of seizures), and heart or blood pressure remedies.
Brain damage from HIE is not a fast process. The oxygen starvation disrupts metabolic activity over time. As a result, it can take days or weeks for the cell death of newborns with HIE to lead to permanent damage. This timeframe also means there is an opportunity for successful medical intervention. Unfortunately, about half of babies with HIE don’t respond to treatment. It is hoped that therapeutic hypothermia could better improve those odds. Annually, approximately one million infants die of HIE and another million survive with disabilities.
The study’s results will be published in an upcoming issue of the Journal of Cerebral Blood Flow and Metabolism.
Sources for Today’s Article:
“Hypoxic Ischemic Encephalopathy (HIE),” Birth Injury Guide web site, http://www.birthinjuryguide.org/birth-injury/types/hypoxic-ischemic-encephalopathy-hie/, last accessed October 9, 2015.
“Protecting Newborn Brains Using Hypothermia,” Children’s Hospital Los Angeles web site, October 8, 2015; http://www.chla.org/press-release/protecting-newborn-brains-using-hypothermia.