Image: HEAD INJURY SOCIETY OF NEW ZEALAND BRAIN INJURY. On impact, the brain bumps into the interior of the skull where it is hit, as well as on the opposite side, resulting in damaging bruises at two sites in the brain, called the coup (blue) and the contrecoup (red). Such injuries can cause a number of long-term effects. |
A concussion is an immediate but reversible traumatic paralysis of the nervous function of the brain. It is usually caused by a blow to the head or by striking the head against a stationary object--blunt traumas that are differentiated as either acceleration or deceleration, respectively. In fact, a concussion is one of eight different types of traumatic brain injuries (TBI) that most commonly result from falls, motor vehicle accidents, sporting accidents and wrongful firearms discharges. (Direct impact is not the only manner of injury: it has been shown in primates that rapid acceleration of the head without impact can also result in concussion, although this injury is rare in humans.)
Indeed, it is the rotational movements of the brain inside the calvaria (meaning all of the cranium except for the facial bones) and the shearing forces affecting the upper reticular formation that create torque, which leads to the typical loss of consciousness. These forces also cause the brain to move in a swirling fashion and contact the inner prominence of the skull, particularly the petrous and orbital ridges and the wings of the sphenoid. Such movement makes the brain bump into the interior of the skull at the point of impact, as well as on the opposite side of the skull, resulting in contusions (bruises) that damage two sites in the brain, called the coup and contrecoup injuries.
More so than the immediate impact (primary injury), however, a concussion involves a host of effects (secondary injuries) that emerge several hours or days after the trauma. It is critical for physicians to monitor these secondary tissue damages, as they are frequently the origin of significant long-term effects, including brain damage, cognitive deficits, psychosocial/behavioral/emotional changes, bodily damage and biochemical changes at the cellular level.
Research has led to discoveries in the use of antioxidant therapy as a proactive measure to counteract the production of free radicals and thus stave off the potential for prolonged cellular damage. Two studies suggest that superoxide radical scavengers and superoxide dismutase may be useful in preventing the development of brain swelling, or edema.
From studies of the intracranial osmolality of cerebrospinal fluid, we have learned that a deliberate induction of hyperosmolality (increasing the intracranial concentration of cerebrospinal fluid) decreases the undesirable neurophysiological response that is characteristic of concussion injuries. Infusing mannitol serves to balance both the frequency and duration of the brain's electrical impulses, averting spikes that otherwise lead to seizure and reducing dangerous elevations in intracranial pressure that can lead to permanent brain damage.
Because so much is at stake when secondary injuries to concussions arise, it is critical that physicians initiate procedures to minimize this effect. In cardiovascular medicine, we remember the tenet "time is muscle," hence "time is white matter." Overall, it is agreed that emergent, aggressive preventive protocols are key for avoiding catastrophic permanent damage to the brain (with concomitant deficits in physical, psychological and behavioral functioning) that irreversibly affects an individual's quality of life.
