What is Second Impact Syndrome?

Second impact syndrome (SIS) occurs when someone sustains a second head injury when the first head injury hasn’t fully healed. SIS typically involves athletes who return to the field while still suffering post-concussive symptoms after injury but it can also occur in those who have been in a car accident or any other related collision. If someone sustains another head injury, he or she can suffer SIS. SIS is rare, and its existence remains a subject of controversy among doctors and researchers. Second impact syndrome can cause brain herniation, diffuse cerebral swelling, cerebral edema, and even death.

Understanding SIS

Anyone who suffers two head injuries close together may be at risk of developing second impact syndrome. Athletes are most at risk, however, as they often have no choice but to continue playing just weeks or even days after a sports-related concussion. Coaches, parents, or self-driven pressure can cause an athlete to cover up concussion symptoms and return to activities before it is safe to do so. Another head injury during this time of recovery could cause SIS and result in brain damage, coma, or death.

A patient with SIS could lose consciousness, suffer memory impairment, or feel disoriented. The person may also experience severe headache. The patient could suffer secondary brain damage, as the brain is more vulnerable in the ten days after a first impact. In a second impact, the brain may lose its ability to stop swelling, leading to major brain injury or death. Incidents of what appeared to be SIS have killed athletes in a matter of two to five minutes after the second impact – too fast for medics to stabilize victims or transport them to the emergency department.

Despite national attention on the danger of concussions athletes face, there remains no concrete answer for when injured parties should return to the game. Sadly, lack of awareness of SIS and other sports-related risks can lead to serious injuries and player death. According to the National Center for Catastrophic Sport Injury Research, the 2015 sports season saw 78 sports-related catastrophic injuries. In total, 13% affected the head and brain, and 33% of those injuries proved fatal. Awareness of second impact syndrome and other harms of letting athletes return to play too soon after a head injury could prevent sports-related catastrophic injuries in the future.

Preventing Second Impact Syndrome

The Centers for Disease Control and Prevention (CDC) recommends only returning to sports-related activities after 24 hours or more have passed from the last time the individual experienced concussion symptoms. Unfortunately, coaches can pressure athletes into returning before they should. This can result in SIS. Here’s what the CDC recommends for concussions to athletes:

  1. Medical examination to assess cognition, balance, neurology, and signs of neurological function deterioration. Medics should consider a history of previous concussions in the evaluation of a patient. No athlete should return to play the same day or receive a “play date” at the time of the emergency department visit.
  2. Complete cognitive and physical rest until the athlete does not experience symptoms for a minimum of 24 consecutive hours. Then, the athlete can return to light aerobic activity, with no jumping or hard running.
  3. The athlete can slowly begin to perform moderate activities, and then heavy, non-contact activity that is closer to the athlete’s typical routine. Only after this stage can an athlete engage in full contact practice and then return to normal competition.

Failure to give someone the necessary time to heal after a concussion can result in second impact syndrome should the individual sustain another head injury. Returning to full activities depends on the individual and a tailored recovery plan from a healthcare professional. It may take months for an athlete to reach this level. Understanding the danger of SIS can help prevent this harm from affecting injury victims and others in the future.