Concussion May Be More Serious Than Thought

This section is compiled by Frank M. Painter, D.C.
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NEW YORK (Reuters Health) ––   A mild blow to the head may cause more brain damage than previously thought. California researchers have found that head injuries that cause concussion can lead to changes that resemble brain damage in the comatose, and these changes can last for weeks.

The finding is important for athletes, especially those in contact sports such as football and ice hockey, who may be at risk for repeated concussions in short frames of time if they continue to play.

“We were very surprised,” said Dr. Marvin Bergsneider from the University of California, Los Angeles, lead author of the study published in the Journal of Neurotrauma. “It really defies standard physiology.”

The researchers took positron emission tomography (PET) scans that show glucose uptake indicating brain activity of 42 people who had suffered mild head injuries such as concussion within the previous month. Most of the head injuries were due to motor vehicle accidents or falls. The results of the study showed that 84% of the patients (36) had a reduction in the metabolic rate of glucose uptake in the brain.

The investigators performed Glasgow Coma Scale (GCS) tests on these study participants. The GCS assesses a person's ability to answer simple questions, such as who and where they are, Bergsneider explained. A level of 3 is deeply comatose, while 15 is the best score.

The team found that 22 of the 36 patients had comatose–level GCS scores (3 to 8). Of the 14 that had higher scores, six had initial scores that were likely lower than 8 but had improved by the time of the PET scan, Bergsneider said.

These patients may have appeared to have mild concussions but truly had more severe injury since small blood clots could be detected on the scan, Bergsneider noted.

It was remarkable that these people functioned as well as they did with such low GCS scores, he said. “They were awake” and able to answer simple questions, but had really intense testing been done, “we would probably find deficits,” Bergsneider said.

It seems that the brain shuts off some functions in order to heal, he suggested, although more research needs to be conducted to confirm that this is what is happening. The changes in glucose use by the brain seen on the PET resolved itself in all patients by the end of the month, he noted.

The significance of this finding lies in the fact that many people, particularly athletes, suffer repeated concussions and may be severely damaging their brain, Bergsneider told Reuters Health. Furthermore, they often put themselves at risk by continuing to play after a period of unconsciousness.

Once the brain has been injured, it “just can't respond to another injury or insult.... There's not a lot of knowledge about this vulnerability to a second concussion,” he said. “We're raising a little alarm. This needs to be studied better.”

SOURCE:   Dissociation of Cerebral Glucose Metabolism and Level of Consciousness
During the Period of Metabolic Depression Following Human Traumatic Brain Injury

J Neurotrauma 2000;   17 (5) May:   389–401

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