is focused on the potential for interrupting the chain of events leading from injury to impairment to functional limitation and disability. Table 5-2 summarizes what is known to be effective in minimizing impairment, maximizing functional capacity, and preventing disability, as well as what needs to be known to develop better and more efficient systems of care.
The nature of the trauma determines the initial severity of the injury to the central nervous system and to a substantial degree also determines the extent of the resulting impairment and functional limitation. Sufficient trauma to the brain may result in cardiopulmonary death, and direct injury to the upper cervical spinal cord may result in death due to paralysis of the muscles of respiration. Should the patient survive the primary injury, however, several other types of injury can occur and increase the extent and severity of impairment and functional limitation. These other types of injury (described below) are secondary injury to the central nervous system, additional second injury to the spinal cord, associated injury to other organs at the time of the initial event, and medical complications of other body systems. A primary role of emergency medical systems, acute care, and medical rehabilitation is to mitigate these effects and ensure maximum function. However, as the National Research Council (1985) and the U.S. Interagency Head Injury Task Force (1989) have noted, more information is needed on effective interventions.
Secondary Injury Primary injury to the brain results in focal hemorrhage or diffuse injury to axons and in hypoxia. The spinal cord, similarly, may sustain initial contusion, hemorrhage, and hypoxia associated with a disruption of the spine and surrounding structures (Becker and Povlishock, 1985). The cascade of events that follow the initial injury often results in further damage (secondary injury) to the nervous system. For example, diffuse brain swelling and space-occupying lesions resulting from TBI can contribute to increased intracranial pressure that can further contribute to ischemia and hypoxia—factors that contribute to impaired function and death. The mechanisms and pathophysiology underlying these changes remain unclear and in need of further research (National Research Council, 1985).
Second Injury The initial trauma of SCI can cause responses such as swelling, hemorrhage, and hypoxia. In TBI patients, drug treatment to remove focal hematomas and control swelling and pressure is helpful, but in SCI patients only modest improvements are achieved. Failure to adequately stabilize the spine during extrication, transport to the hospital, and in the hospital may result in a second injury to the spinal cord, converting an incomplete