Doctors
have long sought a way to directly measure the brain’s temperature
without inserting a probe through the skull. Now researchers have
developed a way to get the brain’s precise temperature with a device the
diameter of a poker-chip that rests on a patient’s head, according to
findings presented May 1 at the annual meeting of the Pediatric Academic
Societies in Denver.
“This
is the first time that anyone has presented data on the brain
temperature of a human obtained non-invasively,” said principal
researcher Dr, Thomas Bass, a neonatologist at Children’s Hospital of
The King’s Daughters in Norfolk, Va., and a professor of pediatrics at
the hospital’s academic partner, Eastern Virginia Medical School.
The
research also suggests that an injured brain can be significantly
warmer than the body, a finding critical to cooling therapies that
reduce brain damage in everyone from elderly heart attack victims to
hypoxic newborns.
“Knowing
the actual brain temperature may allow us to improve outcomes by
keeping the brain at an optimum temperature,” said Dr. Bass.
With
the help of a $750,000 National Institutes of Health grant, a research
team led by Dr. Bass adapted an instrument that calculates temperatures
by detecting microwave emissions produced by all human tissue.
Those
microwaves pass unimpeded through the skull, like light passing through
a sheet of glass. As tissue temperatures increase, the emissions grow
more intense. Engineers calibrated the device to measure the temperature
of brain tissue 1.5 centimeters beneath the skull.
In
the trial whose results were presented, 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. The difference in temperature between the brain and the
body recorded by other means was as high as 5.4% Fahrenheit.
“That’s difference is larger than we expected,” Dr. Bass said.
Dr.
Bass, who pioneered research on cooling therapy for hypoxic newborns,
and set about this research because he believed the therapy could be
improved if doctors knew precise temperature of the damaged organ, the
brain.
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.
Doctors could do little to stop this progression; parents often watched
helplessly as their sons and daughters literally died before their eyes.
Based
on the observation that children rescued from freezing ponds after
extended periods of time suffered little or no brain damage, cooling
therapy involves chilling an infant’s body to 92 degrees for 72 hours
after brain injury.
A
clinical trial on 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.
Because
cooling therapy’s success relies on the temperature of the brain,
precise readings of the brain’s temperature is likely to improve a
therapy that’s already proven remarkably effective.
