Team, physicians, athletic trainers, and other medical personnel responsible for the medical care of athletes face no more challenging problem than the recognition and management of concussion. Indeed, such injuries have captured many headlines in recent years and have spurred studies by both the National Football League and the National Hockey League.
Initially, it was thought a concussion produced only a temporary disturbance of brain function due to neuronal, chemical, or neuroelectrical changes without any physical changes in the brain. We now know that structural damage with the loss of brain cells does occur with some concussions.
Because of advances over the last several years in the neurobiology of cerebral concussion, it has become clear that, in the minutes to days after concussive brain injury, living brain cells may be vulnerable, especially to minor changes in cerebral blood flow, increases in intracranial pressure, and to anoxia (insufficient oxygen to the brain).
Precisely how long this period of metabolic dysfunction lasts is not presently fully understood, and there are no current neuroanatomic or physiologic tests that can be used to precisely determine the extent of injury in concussion, the severity of metabolic dysfunction or precisely when it has cleared.
Recognition and management of concussion is also complicated by the fact that:
Concussion may be caused either by a direct blow to the head or a blow elsewhere on the body with accelerative forces indirectly transmitted to the head. Recent studies of college football players have shown that concussions occur from blows to different parts of the head and of varying magnitude. There is therefore no way to know for certain whether a particular blow will lead to a concussion. A relatively minor impact may result in a concussion while a high-magnitude hit to the head may not.
While concussion usually results in an immediate but brief short-lived impairment of neurologic function which manifest in symptoms, symptoms may not appear until several hours later (the delayed onset of symptoms is more common in athletes under 18 years old);
Though concussion occasionally results in neuropathologic changes, the acute clinical symptoms primarily reflect a functional disturbance rather than a structural injury.
Most concussions suffered by athletes do not result in a loss of consciousness.
Neuroimaging studies (MRIs) are usually normal with concussion.
Given these facts and the evolving nature of concussion science, it is not surprising that management and return to play decisions remain a matter of judgment on a case-by-case basis.