SECOND-IMPACT SYNDROME
Section snippets
WHAT IS THE SECOND-IMPACT SYNDROME?
What Saunders and Harbaugh18 called “the second-impact syndrome of catastrophic head injury” in 1984 was described by Schneider in 1973.19 The syndrome occurs when an athlete who sustains a head injury—often a concussion or worse injury, such as a cerebral contusion— sustains a second head injury before symptoms associated with the first have cleared.5, 6, 14
Typically, the athlete suffers postconcussion symptoms after the first head injury. These may include headache, labyrinthine dysfunction,
PATHOPHYSIOLOGY OF SECOND-IMPACT SYNDROME
The pathophysiology of SIS is thought to involve a loss of autoregulation of the brain's blood supply. This loss of autoregulation leads to vascular engorgement within the cranium, which, in turn, markedly increases intracranial pressure and leads to herniation either of the medical surface (uncus) of the temporal lobe or lobes below the tentorium of the cerebellar tonsils through the foramen magnum (Fig. 1). Animal research has shown that vascular engorgement of the brain after a mild head
INCIDENCE
Although the precise incidence per 100,000 participants is not known because the precise population at risk is unknown, the SIS is more common than previous reports have suggested. Between 1980 and 1993, the National Center for Catastrophic Sports Injury Research in Chapel Hill, NC, identified 35 probable cases among American football players alone. Necropsy or surgery and MR imaging findings confirmed 17 of these cases. An additional 18 cases, though not conclusively documented with necropsy
PREVENTION OF SUDDEN-IMPACT SYNDROME
For a catastrophic condition that has a mortality rate approaching 50% and a morbidity rate nearing 100%, prevention takes on the utmost importance. An athlete who is symptomatic from a head injury must not participate in contact or collision sports until all cerebral symptoms have subsided, and preferably not for at least 1 week after. Whether it takes days, weeks, or months to reach the asymptomatic state, the athlete must never be allowed to practice or compete while still suffering
MALIGNANT BRAIN EDEMA SYNDROME
This condition is found in athletes in the pediatric age range and consists of rapid neurologic deterioration from an alert conscious state to coma and sometimes death, minutes to several hours after head trauma.17, 20 Although this sequence in adults almost always is caused by an intracranial clot, in children pathology studies show diffuse brain swelling with little or no brain injury.20 Rather than true cerebral edema, Langfitt and colleagues12, 13 have shown that the diffuse cerebral
CONCLUSION
As you can see from the preceding description, the malignant brain edema syndrome occur in the pediatric age group after a first head injury and thus, unlike the SIS, is not preventable. Prompt recognition and treatment is thus vital. On the other hand, the SIS is preventable. Because the consequences of this syndrome are so catastrophic and because SIS is more common than previously thought and is not confined to football players, physicians covering all collision or contact sports must be
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Physician and Sportsmedicine
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Second impact syndrome a risk in any contact sport
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Cited by (0)
Address reprint requests to Robert C. Cantu, MD, FACS, FACSM, Service of Sports Medicine, Emerson Hospital, Concord, MA 01742
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Neurosurgery Service and the Service of Sports Medicine, Emerson Hospital, Concord, Massachusetts