Second Impact Syndrome in NFL Players

By Terry Zeigler EdD, ATC

Zachary Lystedt suffered a head injury in an 8th grade football game, but returned to the field and continued playing. The star athlete played the entire game before collapsing on the field. He was diagnosed with second impact syndrome (SIS). He is now disabled, and his family has devoted their time to preventing other young athletes from suffering the same fate.


What is second impact syndrome?

Second impact syndrome occurs when an athlete returns to sport too early after suffering from an initial concussion. The athlete does not need to receive a strong second blow to the head to set the effects in motion. The athlete may receive only a minor blow to the head or a hit to the chest or back that snaps the head enough to have the brain rebound inside the skull.

Because the brain is more vulnerable and susceptible to injury after an initial brain injury, it only takes a minimal force to cause irreversible damage. The brain’s ability to self-regulate the amount of blood volume to the brain is damaged resulting in increased cerebral blood volume which can result in brainstem herniation and death.

The pressure to the brain increases rapidly causing brain death in as little as three to five minutes. Because brain death is so rapid, second impact syndrome has a high fatality rate in young athletes.


How is second impact syndrome diagnosed?

If a brain injury is suspected, an immediate computed tomography (CT) of the head should be ordered. A CT scan is more sensitive than an MRI to detect acute intracranial bleeding. A thorough medical history specifically regarding mechanism of injury and history of head injury should be obtained from the patient if the patient is conscious or from an eyewitness if the athlete is rendered unconscious.


What are the signs and symptoms of an athlete suffering from second impact syndrome?

Initially, the athlete may not lose consciousness, but may look stunned. The athlete may also be able to make it to the sideline where the athlete may suddenly collapse within minutes.

The condition worsens rapidly will loss of consciousness, loss of eye movement, dilated pupils, coma, and then respiratory failure. This can all take place within minutes on the sideline.

Because this is a life-threatening emergency, life-saving measures must be taken within minutes for there to be any hope for the athlete. Treatment should be undertaken to maintain an airway, and to provide rescue breathing and CPR if necessary.


It is logical to conclude that sports in which concussions are more prevalent will also be sports in which athletes will be more at risk for SIS. According to Sullivan, J.A., and Anderson, S.J. (2000), SIS is most often reported in boxers and football players.


What is the treatment for second impact syndrome?

The treatment for SIS is to stabilize the patient with a special emphasis on airway management. Once the CT scan has been completed and the CT scan confirms that there is an increased intracranial pressure, the goal is to “normalize the elevated intracranial pressure by restricting cerebral blood flow or fluid to the brain tissue” (Bahr, R., & Maehlum, S., 2004). Possible treatments include hyperventilation, diuresis, fluid restriction, blood pressure control, steroids or surgery when indicated.


What is the prognosis for an athlete with second impact syndrome?

As stated above, second impact syndrome has a high mortality rate in young athletes. Patients that survive may suffer from permanent neurological symptoms including impacting the following systems:

• Speech
• Cognitive ability
• Sensory ability
• Vision
• Perception
• Hearing
• Smell
• Taste
• Social/emotional interactions





  • Arnheim, D. & Prentice, W. (2000). Principles of Athletic Training. (10th Ed.). McGraw Hill: Boston, MA.
  • Bahr, R. & Maehlum S. (2004). Clinical Guide to Sports Injuries. Human Kinetics: Champaign, IL.
  • Bey, T. & Ostick, B. (February, 2009). Second Impact Syndrome. Western Journal of Emergency Medicine: 10(1): 6-10.
  • “How Often do Concussions Occur? Sport concussion Epidemiology. Accessed May 20, 2010.
  • “The High Price Athletes Pay to Compete in High Risk Sports”. Accessed May 20, 2010.
  • Sullivan, J.A. & Anderson, S.J. (2000). Care of the Young Athlete. Published by the American Academy of Pediatrics and American Academy of Orthopedic Surgeons.


No Comments

Sorry, the comment form is closed at this time.

Pin It on Pinterest

Share This

Subscribe To Our Weekly NFL Injury Report

Receive NFL injury analysis from our top sports doctors.

You have Successfully Subscribed!