It is not uncommon for a person to strike their head on some portion of the inside of their car or truck when involved in a collision.  The mechanics of what happens to the human body when inside of a car in a crash are quite well understood.  Generally, your body moves in the direction of impact to your car.  So for example, if you are driving and you get hit “T-Bone” style directly against your driver’s door, your entire body will move towards that door and most likely strike up against it.  In that scenario, since your head is in the center of your body, it will snap like a whip and you will strike the left side of your head against the window or pillar of the car.

     When your head is put in motion and strikes some part of the car, it can easily cause head injury of either a minor nature, or catastrophically bad injuries.  Obviously, our brains are inside of our heads, and that is a part of the body that most people would prefer to never injure.  When your head snaps around in an accident, and strikes some interior portion of the car, your brain is moving inside of your skull. 

     The skull protects our brain.  The skull is very hard, which is good to prevent external assault into the brain, but kind of a bad thing when the brain starts moving inside of our head in an accident.  The brain is “cushioned” in our head with cerebral spinal fluid.  When the head snaps forward or sideways in an accident, the brain lags slightly behind and then strikes first one-side and then bounces back and most likely strikes the opposite side of the skull interior.  Depending on the accident, that shearing action can happen once or several times.  The brain’s movement in the head and striking opposite sides of the skull is called the “coup-contracoup” effect. 

     When our brain gets sloshed around inside the skull, striking the inside sometimes very forcefully, damage can be caused that is readily observable on certain types of exams.  For instance, if you severely bang your head, it can cause bleeding in the brain (sub-dural  hematoma) which if not promptly and carefully treated can result in certain death.  However, even if there is no obvious  bleeding, the force of the brain moving in the skull can cause shearing axonal injury on a cellular level.  That type of an injury is not readily apparent on a CT Scan or even most MRIs.  Though not easily visible, shearing axonal injuries can be extremely serious because they interrupt the usual flow of communication in the brain and can have serious repercussions from such things as post-traumatic migraine headaches, memory loss, speech pathology, etc. 

     So how do you know if you have a head injury and whether it is serious?   The golden rule answer is that even minor head injuries are significant and should receive the careful attention of emergency room doctors and your own primary care physician.  The types of things to look for to know whether you may have a head injury include:  loss of consciousness, headache, bruising and/or head swelling, bleeding, etc.  Obviously, if you have banged your head, get the doctor to look at it!   In kids, it is a little trickier to know whether your toddler is just got a little bump, or whether it is more serious.  Some things to consider is whether your youngster got knocked out, is she lethargic, unsteady gait, complaining of a headache, starts vomiting within a short time after the  event.  These are not intended to be exclusive lists of things to look for, rather a reminder that ALL cases of head trauma are potentially very serious.  Consequently, do not risk your life or your youngsters by thinking it is just a bump—it may be, but what if your wrong??  If you or your child hit your head in an accident, TELL the EMERGENCY ROOM DOCTORS!!  If you did not go to the emergency room, keep a constant awareness for any changes in your condition.  Are your too sleepy?  Baby too crabby?  Unsteady on feet?  Slipping in and out?  Vomiting?  Pale? Vision problems?   Don’t delay–call your doctor.  Be safe and stay alive.