October 27, 1996|By Howard M. Eisenberg
Spinal cord injury is clearly a national health issue. Its toll is heavy, both in human and economic terms. Approximately 10,000 people with spinal cord injuries are admitted to U.S. hospitals every year, and an estimated 9,000 of them survive with severe disabliities. Further, this injury most frequently occurs in early adult life - the mid-20s - and therefore imposes a high cost, not only financially (funding for long-term care and expenses due to loss of productivity), but also in physical and emotional hardship endured by those injured and their families.
Earlier this month a group of leading scientific investigators met in Bethesda to discuss their research in spinal cord injury. The National Institutes of Health-sponsored workshop, "Spinal Cord Injury: Emerging Concepts," attracted an audience of almost 300, including investigators and representatives of the NIH, as well as representatives of public interest groups.
Dana Reeve represented her husband, Christopher Reeve, both of whom have become outspoken advocates for support of spinal cord injury research. The workshop, the largest of its kind, was also supported by the American Paralysis Association, Paralyzed Veterans of America and the Kent Waldrep National Paralysis Foundation.
The goal of the workshop was to bring together investigators who have made important contributions to the understanding and treatment of spinal cord injury. The timing was appropriate, as important advances in clinical and basic research have been made in the past several years, and public awareness of spinal cord trauma has been heightened by Reeve's injury.
The spinal cord, extending from the base of the brain to approximately the level of the waist, is the pathway for communication between the brain and the body. Through this communication pathway, the brain receives information about the internal and external environment.
Sensory organs in muscles and skin provide information about position, touch and temperature, as well as painful, potentially dangerous stimuli from almost all other organs. Most important, the brain sends information to muscles that make possible, for example, locomotion (walking and running), reaching, fine hand movements and control of breathing.
The spinal cord is encased within the segments of the bony spine like a cable protected by a series of rigid rings
interconnected so as to allow flexibility. Despite its protective covering, the cord can be injured by violent movement, which can cause rupture of the ligaments interconnecting the bony segments, rupture of discs interposed between these bony segments or fracture of the bony segments themselves.
Fractured fragments, ruptured disc, or displacement and loss of alignment of the bony rings causes crushing of the delicate spinal cord, which can then be severed, partially severed or bruised.
During the past decade, scientists have learned that bruising alone can cause serious problems. Bruising of the spinal cord produces a sequence of events that can cause permanent injury, and this kind of injury can continue for at least several hours after the moment of impact has passed.
This secondary injury happens because toxic substances, normally released by cells in very small amounts, flood the liquid spaces between cells after injury, and at these high concentrations, these toxic substances are capable of spreading permanent injury to neighboring uninjured cells.
Devising new drugs to combat this process was a major topic considered at the NIH workshop.
Considerable progress already has been made. An established steroid, methylprednisolone, has been shown to be effective in reducing injury.
In a study, subjects were randomized so that half of the more than 400 patients enlisted received this drug at very high concentrations, while the other patients received the best standard therapy. The results of this study, reported in 1990 in the New England Journal of Medicine, indicated, however, that there was only a relatively narrow window for successful intervention: less than eight hours after impact.
The time for other treatment may also be critical. It is important for injured individuals to reach a trauma treatment center as soon as possible after a spinal injury. To this end, citizens of Maryland benefit from our state's highly organized and efficient Emergency Medical System. Investigators are now in search of an even more effective drug.
Also promising is a study recently reported in the journal Science, showing that an experimentally severed spinal cord could regenerate nerve fibers across the transection, provided that specialized cells as well as newly discovered growth factors were transplanted into the gap. Injured rats not only regenerated RTC nerve fibers but regain their ability to walk. Considerable discussion at the workshop was devoted to this idea.
Another important area of research considered by workshop participants was the use of neuronal implants that can deliver highly coordinated electrical stimulation to the spinal cord or to the affected muscle.
Researchers agreed that there is a pressing need for more clinical studies to test new drugs and novel approaches such as neural regeneration, growth factors and transplantation, and electronic implants.
While the future now seems promising with regard to more effective therapies, no discussion of traumatic injury would be complete without a reminder that many of these injuries are preventable and that all of us must take responsibility for safety.
Howard M. Eisenberg, M.D., is professor and head of the Division of Neurosurgery at the University of Maryland School of Medicine. He also is director of the Program in Trauma at the R. Adams Cowley Shock Trauma Center.
Pub Date: 10/27/96
