As most parents know, minor head trauma is incredibly common in children. Most active kids will at some point will either hit their head from a fall, run into an immovable object with their head, be struck in their head with some other object, fall off a bike or down the stairs, fall out of the grocery cart, have a sports related head collision, etc. Fortunately, most of these injuries are very mild and require no treatment whatsoever. The child’s brain is protected by a very rigid skull and, beneath which, is essentially cushioned by a water bath.
However, head trauma may – under rare circumstances – may result in more severe injury. And, unlike a broken bone, it is often not obvious when such an injury may have occurred. For this reason, head injury remains a very common reason parents bring their children for medical evaluation. Over 600,000 emergency department visits annually in the U.S.A. are due to head trauma. And, in the vast majority of cases the etiology of the head injury is relatively mild (as compared with, say, a high speed motor vehicle accident).
In the emergency department, about 50% of all head injuries are evaluated by a head CT scan. A CT scan is a powerful x-ray of the brain that is very quick (about 3 minutes) and allows detection of most severe injuries to the brain that would require emergency treatment (such as a bleed inside the skull).
However, the dose of radiation a patient receives during a head CT is about 200 times that of a chest x-ray. Over the past 5 to 10 years the medical profession has had an increasing appreciation of the risks that may be associated with this degree of radiation exposure. Some now estimate that as many as 1 in 1000 to 5000 head CTs result in a cancer that would otherwise not have occurred.
Therefore, no patient should undergo a CT scan unless the benefit outweighs the risk. The problem is that the risk is almost never crystal clear, and many physician’s and parents want to err on the side of caution fearing they would miss even one child who might have a serious injury. Fortunately, recent studies help guide physicians and parents as to who may be at extremely low risk for having a serious problem after a head injury.
For example in the case of a child under 2 years of age, if the child meets the following criteria after injury, their risk of having a serious brain injury is almost zero:
- If they have normal mental alertness
- If they have no bruise or swelling on their head other than their forehead
- If they have not lost consciousness for more than 5 seconds (yes, very brief loss of consciousness does not seem to predict a serious problem if everything else is OK)
- If the mechanism of the head injury is not severe (not a high speed collision)
- No obvious skull fracture
- And the child is behaving normally in the view of the parents
In the case of children over 2 the criteria are slightly different, but similar:
- The child has normal mental alertness
- There was no loss of consciousness
- The child is not vomiting
- The mechanism of the injury is not severe
- There is no bruising under the eyes
- And the child does not have a severe headache
As with any clinical guidelines based on results from even the best studies, predictive criteria will never be right in every single case; therefore, parents should always seek medical attention if they have concerns. However, the above guidelines can be used to reassure parents that if their child meets all the criteria listed above after a minor head injury that their child risk of a life-threatening outcome is extremely remote. Additionally, even if medical care is sought, the parents and physicians should both consider the risks vs benefits of a head CT before obtaining that study.
Mike Cinoman is a pediatric intensivist in the WakeMed Children’s Hospital.