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Does Second Impact Syndrome Exist?

McCrory, Paul MBBS, PhD

Clinical Journal of Sport Medicine: July 2001 - Volume 11 - Issue 3 - p 144-149
Thematic Articles

Second impact syndrome (SIS) is a widely feared complication of traumatic brain injury. Although postulated to occur after repeated concussion, the evidence for such a premise is not compelling. This paper reviews the published evidence for and against the existence of this controversial entity. Rather than SIS being a complication of recurrent concussion, it is far more likely that the clinical condition represents “diffuse cerebral swelling,” a well-recognized complication of traumatic brain injury. This condition is more common in children and adolescents, which reflects the known demographics of so-called “second impact syndrome.” We propose that clinicians abandon the misleading term second impact syndrome and refer to the syndrome as diffuse cerebral swelling.

Centre for Sports Medicine Research & Education, and Brain Research Institute, University of Melbourne, Melbourne, Australia

Address correspondence to Paul McCrory, MBBS, PhD, 31 Grosvenor Parade, Balwyn, Victoria 3101, Australia. E-mail: pmccrory@

© 2001 Lippincott Williams & Wilkins, Inc.