According to Frontiers in Neurology / Endovascular and Interventional Neurology December 2011 /Volume 2 /Article 80/ the authors stated, “further investigations are needed to determine clinically applicable, non-invasive, accurate ways to approximate brain temperature. ‘(p.4) The query comes from, specifically the Departments of Neurology, Surgery, Integrative Biology and Physiology and Neurosurgery from the University of Minnesota. So we have body temperature and these people like I have stated before, we do have a separate brain temperature. The Swedish neurosurgeon Mellergard actually measure in human brains, what he termed a brain thermal gradient.
Finally researchers are starting to get it, about measuring brain temperature. Dr. Thomas Bass is developing a gizmo that actually measures part of the output loop of brain temperature, using the micro waves generated within the brain’s tissue but only down to a distance of 1.5 cm beneath the cranial bone. The device is in contact with the head, reading the energy of the microwaves as an interpreted value.
Researchers develop device to measure brain temperature non-invasively
Non-invasive brain-temperature monitoring could be critical in life-saving cooling therapy
DENVER, CO – 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.
So here is my definition of brain temperature. I thought what I had created before from my own experiments 20 years ago measuring a different temperature measurement for the brain versus the body at the same time from a previous posting in Dr Pappius lab at the Montreal Neurological Institute. It’s clear that the engineering term of a set point is the usual way we think of how the temperature is regulated. You have this temperature say 37 C that any variance should be brought back to the control point that regulates the brain temperature. It’s a lot more complicated. It looks like there are multitudes of set points. Here’s why. Mellergard has measured thermal gradients, a range of temperature within the human brain, the core to cortex differential is as high as 3-4C different from the hotter core of the brain to the cooler cortex. That is one direction core to cortex, what about front to back, what about any radius of distance within the brain? I’m starting to realize no matter where you go, in terms of a distance comparison within the brain you have temperature changes all along the way. It all depends on the blood flow. It looks like flow is balanced with temperature. The blood vessels within the brain are not just conduits bringing nutrients to the neurons. Here’s some info to help explain this from a 2008 Scientific American article written by Nikhil Swaraminathan on A Blood-Brain Balance:
When a brain region becomes active, a flood of blood arrives within a few hundred milliseconds to service local neurons with the oxygen and glucose they need for energy. Scientists exploit this flow when they use functional magnetic resonance imaging to determine what parts of the brain respond to different stimuli. Recent estimates, however, peg the rush of blood to be nearly 10 times the amount neurons need for metabolism.
Now neuroscientist Christopher I. Moore of the Massachusetts Institute of Technology has proposed a new theory behind the excess flow—the blood, he says, may actually be involved in information processing in the brain. Moore’s “hemo-neural hypothesis” posits several mechanisms for how blood might modulate neuron activity. Molecules in the blood might diffuse into the brain and affect neurotransmitter release, or changes in the volume, pressure or temperature of blood vessels may stress neuronal membranes to regulate transmission. Or there may be a middleman—astrocytes, the nonneuronal supporting cells that surround capillaries in the brain, could secrete chemical signals to neurons in response to a change in blood flow.
Previous research supports Moore’s idea, such as the recent work on Alzheimer’s disease suggesting that vascular decline may precede, and facilitate, neurodegeneration. Further, if blood were to play a tempering role, disruptions in its flow could explain the mechanism behind epilepsy, which can result from overexcited neurons.
Although some in the neuroscience community are dismissive, many believe that a true model of brain processing must include some role for blood. If his hypothesis proved true, Moore says, cerebral blood flow would no longer be thought of simply as a means to investigate brain function. “It would be a Heisenberg sort of thing,” he suggests, referring to the way observing a quantum state changes it, “where what you’re looking at is actually a part of the computation going on.”
Did you notice the part I highlighted from Christopher Moore’s work? The temperature of neuronal blood vessels may regulate neurotransmission, by stressing the neuronal membranes. WOW if that isn’t the tensegrity (tension balanced to compression) stressing relationship that I have been getting excited about. Here’s the shape sensing mesh-link of communication between cells that I’ve been trying to take my brain around. So let’s step back take a breather to be the observer for one instant here. Imagine shrinking down to watch as if you’re there. Here’s me talking: “All these neurons, astrocytes, glial cells, blood vessels, ion channels-opening closing- it’s like I’m sitting in some sort of stadium with all these attachment cables going in all different directions. Look everything is mobile it’s all moving, it’s like I feel the temperature of the blood vessel near me changing as the astrocytes tethered shapes deform, interacting, shapeparts of everything are changing, the whole thing is moving all the time !”
So to get back to my term for brain temperature. I suggest brain loop temperature, it gives a better feeling for the range of temperature depending on the local activity within a zone, within a brain loop of control. The term that I had created myself, brainsett, as two brain thermal set points doesn’t capture the exquisite dimension of temperature control loops in all directions. But brain temperature definitely deserves it’s own unique descriptive term.