Specifically, there is an increase in the demand for glucose coupled with a decrease in cerebral blood flow. This increase in demand lasts for as little as a few days to as much as one week in some animal studies. It has been observed in humans that this period of hyperglycolysis lasts as long as two weeks and that metabolic depression may last as long as one year. The reduction in cerebral blood flow has been linked to the vasoconstrictive effects of local endothelial accumulation of calcium. Studies indicate a two-fold increase in locally traumatized areas.
Calcium mediates a cascade of events leading to vasoconstriction.
In severe head injuries, it has been demonstrated that calcium channel blockers can reduce this reactionary vasoconstriction and increase cerebral blood flow. The biggest difficulty at this time is tying together these physiologic events with patient signs and symptoms. Always check for subtle signs of fracture, with careful attention paid to palpation of the head and face and otologic evaluation of the ears. When asking about symptoms such as headache, dizziness, ringing in the ears, double vision, etc., recognize that many athletes minimize and under-report these symptoms in an attempt to get back into play. If signs and symptoms clear within 15 minutes, challenge the athlete with exertion and provocative position in an attempt to increase intracranial pressure.