Noninvasive Device Measures Human Brain Temperature

The brain's precise temperature can be measured using a device the diameter of a poker-chip that rests on a patient's head.

The finding that an injured brain can be significantly warmer than the body is critical to cooling therapies that reduce brain damage in everyone from elderly heart attack victims to hypoxic newborns.

A team led by Dr. Bass, a neonatologist at Children's Hospital of The King's Daughters (CHKD; Norfolk, VA, USA) and professor of pediatrics at the hospital's academic partner, Eastern Virginia Medical School, adapted an instrument that calculates temperatures by detecting microwave emissions produced by all human tissue.

The microwaves pass unimpeded through the skull; as tissue temperatures increase, the emissions grow more intense. Engineers calibrated the device to measure the temperature of brain tissue 1.5 cm beneath the skull.

In a trial whose results were presented on May 1, 2011, at the annual meeting of the Pediatric Academic Societies in Denver (CO, USA), the device was placed on the heads of infants undergoing cooling therapy at CHKD. The device's brain temperature readings were correlated with rectal and esophageal temperatures

Hypoxic brain damage in infants occurs most often in full-term births when the child suffers oxygen loss either immediately before or during delivery. Because of a quirk in the brain, a child can be revived but brain cells continue to die over several days, resulting in brain damage or death.

Based on the observation that children rescued from freezing ponds after extended periods of time suffered little or no brain damage, cooling therapy was developed. It involves chilling an infant's body to 33.33 °C for 72 hours after brain injury.

A clinical trial testing the therapy showed that cooling the child stops or reduces the progression of brain cell death, drastically reducing brain damage and death. The results were so positive that the therapy is now standard in advanced neonatal intensive-care units worldwide.

Cooling therapy is now used with other patients as well, including heart attack victims whose brains have suffered oxygen deprivation. However, because cooling therapy's success relies on the temperature of the brain precise readings of the brain's temperature are particularly important.

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Children's Hospital of The King's Daughters