What is Second Impact Syndrome?
Second impact syndrome (SIS) is a medical condition that occurs when a person suffers a second head injury before fully recovering from the first one. This syndrome has increasingly become a topic of concern, particularly with athletes who go through a concussion and get back on the field before they have fully healed.
While SIS isn’t very common, it’s extremely important that doctors are aware of it and let patients know about it as well, especially ones who have had a head injury or could possibly get one. This is because if not treated properly, SIS can often lead to death.
The term “second impact syndrome” was first used in the medical field in 1984. Doctors Saunders and Harbaugh coined it when they were talking about a football player who had a head injury and got back on the field too soon. He suffered another head injury four days later, and sadly, he died from it.
What Causes Second Impact Syndrome?
Second Impact Syndrome (SIS) is a rare condition that’s not fully understood yet. According to the Centers for Disease Control and Prevention, between 1.6 to 3.8 million sports-related head injuries happen in the US each year. While we generally know the cause of a concussion, the cause of SIS is still unclear.
The common cause seems to be when a second concussion happens before the brain has had time to fully recover from the first concussion. This can cause the person to quickly lose consciousness and suffer severe brain damage. This happens because the blood flow in the brain malfunctions, triggering an increase in pressure within the skull. This pressure builds up swiftly and can result in parts of the brain being squeezed, either across the middle part of the brain or downwards through an opening at the base of the skull. This can lead to damage in the brain stem, quick worsening of the person’s condition, and could possibly lead to death within 2 to 5 minutes.
A recent case report provides a helpful example. An athlete went back to practice five days after an initial concussion. Despite getting an ordinary CT scan on day four, he continued to have a severe headache. After getting hit during practice on day five, he collapsed after saying he had a headache and could not feel his legs. Another CT scan at a local emergency department showed thin bleeding on the surface of the brain on both sides. However, an additional MRI showed that the injury caused the middle structures of the brain to be pushed downwards, resulting in a type of brain herniation.
Risk Factors and Frequency for Second Impact Syndrome
In a research article analyzed in 2016, a search found that only 36 instances of second impact injuries in athletes had been reported in 15 different studies. Out of these, only 17 cases fit the criteria for further investigation. The typical profile for an athlete at risk for a second impact injury was a male, aged between 13 and 24 years old, who played contact sports like American football, boxing, or hockey.
- Out of the 17 cases, 7 athletes received a direct hit to the head, while the others probably experienced a blow to the body that affected their head.
- Using a CT scan, 4 of these cases showed widespread brain swelling, brain shifting, leading to a condition called herniation.
- All of these athletes had either small or moderate brain bleeds, known as subdural hematomas.
- 2 of the athletes experienced another type of brain bleed called a subarachnoid hemorrhage.
- 3 of the athletes had an ischemic stroke, which is a type of stroke caused by a blood clot.
Signs and Symptoms of Second Impact Syndrome
If an athlete goes back to playing sports after having a concussion, they should be monitored closely, even if they’ve had enough time to recover and have followed all the necessary steps to return to the game safely. A person who has had a concussion might experience a variety of symptoms, such as headache, dizziness, memory problems, blurred vision, confusion, tiredness, sensitivity to light or sound, loss of motor skills or sensation, trouble with coordination, or fluctuating emotions. During a physical exam, they might seem less aware, have trouble remembering things, or have problems with focus and balance. They might also have issues with sensation, movement, or vision. If the player wasn’t unconscious but stayed in the game, they might seem unsteady, run in the wrong direction, or react slowly.
As people have become more aware of concussions and the problems that can come from not allowing the brain enough time to heal, tests have been developed to evaluate the athletes’ cognitive abilities at the scene. Short neuropsychological tests that look at attention and memory are helpful in these cases. Examples include the SCAT5, which uses Maddocks’ questions, and the Standardized Assessment of Concussion (SAC).
- Headache
- Dizziness
- Memory problems
- Blurred vision
- Confusion
- Tiredness
- Sensitivity to light or sound
- Loss of motor skills or sensation
- Trouble with coordination
- Fluctuating emotions
In cases where it’s thought that an athlete may have had a second concussion before the first one has healed, that player’s Glasgow coma scale score, pupil reaction, deep tendon reflexes, clonus in the arms and legs, and the presence or absence of a Babinski reflex can be checked before they’re taken to the hospital or once they get there. It can be tricky to decide what defines a second concussion as this condition has been the subject of limited research and its symptoms can worsen quickly. One approach might be for clinicians to assume that any concussion in male athletes aged 13 to 24 could potentially be a second concussion and keep a close eye on the injured person’s symptoms to see if they get worse.
Testing for Second Impact Syndrome
If a doctor suspects that you may have had a brain injury, they will try to gather as much information as possible about what happened. This includes trying to understand how the injury occurred, whether you’ve had seizures or concussions before, if you were using alcohol or drugs at the time of the injury, whether you lost consciousness, any weakness or numbness you might be feeling, if you’ve have difficulty walking, and whether you’ve lost control of your bladder or bowel movements.
People who have experienced a serious injury or lost consciousness, those with ongoing symptoms or a decline in neurological function, or those with neurological deficits may need to undergo imaging tests. The doctor might also recommend testing for alcohol or illegal drugs. CT scans, which provide detailed images of the brain, are usually the preferred method for diagnosing an acute head injury because they are highly effective at detecting bleeding in the brain and potential injuries that may require surgery.
Current medical guidelines recommend a CT scan in cases where a skull fracture, brain bleeding or other brain disorders are suspected based on physical examination. If you’ve lost consciousness due to the injury, it would be a good idea to start with a CT scan of your head.
Treatment Options for Second Impact Syndrome
Second Impact Syndrome, often known as SIS, is somewhat challenging to manage since there is limited research and understanding about it, and its nature is quite controversial. It typically starts with quickly acknowledging that an athlete has possibly sustained a concussion during a sports activity, and then ensuring their safety until they have fully recovered from that initial injury.
Presently, the main guidelines for treating SIS involve relative rest. This means both mental rest, not doing activities that require a lot of thinking or concentration, and physical rest (resting the body and avoiding strenuous activities). After that, the person affected is allowed to gradually begin participating in their sport again. Ideally, a team doctor who has experience in dealing with concussions should oversee this process, along with their athletic training staff.
It is absolutely crucial that the person should not be allowed to fully participate in their sport again until they have gone through this return-to-play protocol, and a medical professional gives clearance, thereby confirming that it is safe for the person to return to their sporting activities.
What else can Second Impact Syndrome be?
When trying to diagnose Second impact syndrome, doctors look into other conditions that can have similar symptoms. These conditions include:
- Bleeding in the space surrounding the brain (Subarachnoid bleed)
- Stroke caused by lack of blood supply (Ischemic stroke)
- Blood collecting on the brain’s surface beneath its outer covering (Subdural hematoma)
- Fracture in the base of the skull (Basal skull fracture)
- Fracture in the skull (Skull fracture)
Preventing Second Impact Syndrome
The best way to avoid a condition called “second impact syndrome” is through primary prevention, which is taking steps to stop something from happening before it starts. It’s important that parents and athletes understand the potential dangers of a concussion, what symptoms to look for, and how long it typically takes to recover. This includes talking about the risks of going back to sports too soon, which could lead to longer recovery time, ongoing symptoms, and a second impact syndrome.
Second impact syndrome is a serious condition that can occur if an athlete has a second concussion before symptoms from the first one have completely gone away. So, getting support from parents and coaches can really help athletes in not downplaying their symptoms and in avoiding a premature return to their sport.
In most cases, safety guidelines recommend waiting at least seven days before an athlete who’s had a concussion may be allowed to go back to playing. Each case can be different, so it’s crucial to follow the doctor’s advice and not rush the recovery process.
