Acute and long-term management of sports-related closed head injuries

What Definition Is Used to Describe Second Impact Syndrome in Sports? A Systematic and Critical Review

Concern about what has been termed, "second impact syndrome" (SIS) is a major factor determining return-to-play decisions after concussion. However, definitions of SIS vary. We used Scopus to conduct a systematic review and categorize the definitions used to describe SIS. Of the 91 sources identified, 79 (87%) clearly specified that SIS involved either cerebral edema or death after a concussion when a prior concussion had not resolved. Twelve articles (13%) could be interpreted as merely the events of two consecutive concussions. Among the articles that listed mortality rates, nearly all (33/35, 94%) said the rate of death was "high" (e.g., 50% to 100%). Our review found that most articles define SIS as a syndrome requiring catastrophic brain injury after consecutive concussive episodes. Given that it is unclear how common it is to have a second concussion while not fully recovered from a first concussion, the actual mortality rate of SIS is unknown.

Vomiting as a reliable sign of concussion

Concussion is the most common type of traumatic brain injury, with headache being the most frequent symptom of mild traumatic brain injury (MTBI) (including dizziness, vomiting, nausea, lack of motor coordination or difficulty balancing). Concussion may be caused by a blow to the head, or by acceleration forces without a direct impact. Often, MTBI occurs as the result of a sports injury. Loss of consciousness is always present, unlike vomiting. Therefore, we hypothesize vomiting to be considered as a cardinal sign of concussion. Stimulation of vomiting centres finally triggers vomiting. Professional boxers and mixed martial arts competitions reluctantly agree with stringent rules and protective clothing. We discuss the issue of further protection for those engaged in these and other sports.