Does second impact syndrome exist?

Clin J Sport Med. 2001 Jul;11(3):144-9. doi: 10.1097/00042752-200107000-00004.


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.

Publication types

  • Review

MeSH terms

  • Adolescent
  • Adult
  • Athletic Injuries / complications*
  • Brain Edema / epidemiology
  • Brain Edema / etiology*
  • Brain Edema / mortality
  • Brain Injuries / complications*
  • Humans
  • Male
  • Sex Factors
  • Syndrome