Skip to main content
Athletics » Second Impact Syndrome

Second Impact Syndrome

Second Impact Syndrome

What is Second Impact Syndrome?
Second Impact Syndrome (SIS) occurs when an athlete who sustains a head injury subsequently 
receives a second head injury before full resolution of the first symptoms. Re-injury need not 
occur on the same day and has been reported up to four days following the first concussion with 
brief loss of consciousness (Erlanger, 1999). 

At the time of the second concussion, the impact might appear minor and the athlete may just 
appear slightly dazed and be able to walk off the field under their own power.  However, real 
effects of SIS will kick in and usually happen at this point.  The athlete could collapse, lose 
consciousness, have respiratory failure, and death may even occur. 

 

Who does SIS Effect?

Some of the research that has been completed on SIS, indicates that athletes under the age 
of 21 are at greater risk to suffer from SIS than older athletes,  “…also to be noted that a 
review of the Second Impact Syndrome reveals no cases in which the individual is more than 21 
years of age” (Erlanger, 1999). 

 

Real Life Stories of SIS