What's the one part of the human body that doesn't heal quickly (or at all) if injured? Forty to fifty percent of brain injuries occur in vehicular mishaps and even in cases of minor injuries, the long term effects can be permanent and life-altering. For kids, 20% of head injuries result from cycling accidents. Legs, arms, ribs, and many other "parts" can heal, but quite often, brains don't, at least not in the way we want them to.
If a head injury is classified as "minor," most victims fully recover in 3 to 4 months (still, some don't). For moderate head injuries, recovery more likely takes 6 to 9 months. If the injury is severe, recovery for "most" victims is much less likely at all. According to Headway, an association for brain injuiries in the United Kingdom, long term -- and even permanent -- effects for any level of brain injury can include:
loss of sensations
reduced perception, recognition and judgment
loss of initiative
inability to concentrate
physical disabilities and loss of basic motor skills
poor cognitive and communication skills
Without even considering the physical pain and headaches involved, does this sound like the kind of life you want to live?
Once the brain is injured, complications (and further damage) can result from lack of oxygen through blood loss or blockages, and/or from rising pressure and swelling in the cranial cavity within the skull. According to Headway, "the only cure is prevention."
It is not necessary to bang your head against something in order to sustain a brain injury - the whipping movement possible in a collision (whiplash, for example) can cause injury by twisting or stretching the thousands of nerve fibers and soft tissues in the brain, and also result in ruptures of the veins and arteries within it. Make certain your head restraints are adjusted properly, and wear your seat belts. The head restraint should be raised up where it is behind your HEAD, not your neck. In a lower position, it will actually make your injuries worse, as it acts as a pivot around which your head can rotate.
Another source of head injuries is being ejected from your vehicle. In any wrecking yard, you'll find vehicles where people were thrown into the windshield, leaving a circular shatter-pattern in front of their position. Head injuries also occur when vehicle occupants are thrown headfirst into solid objects outside -- such as a telephone pole. Wear seat belts and shoulder harnesses to keep you inside the vehicle where you are afforded some protection.
It doesn't take much force to cause serious brain injuries -- impacts as low as 4 mph can cause fatalities. I knew someone who died in a very low speed impact, and my friend's death has made this a matter of personal importance to me.
Some other methods of transportation increase the chances of head injuries. Many years ago, I was flung off my motorcycle at about 45 miles per hour. During the accident, I recall that my body seemed to naturally gravitate toward a head-first impact. Hospital trauma center personnel know that a head injury is the likely result of a motorcycle collision -- and the same is true for bicyclists. I always wear a helmet, and not a cheap one, either. I buy the best money can buy. Bicyclists should take the same precaution -- a good helmet may be all that stands between a rider and life in a "vegetative state."