Whiplash injuries from rear impact collisions
In the U.S. approximately 3 million persons are hurt in low speed (under 12 mph) rear-end automobile accidents each year and the numbers are increasing because our cars are actually becoming less safe for this kind of crash as a result of the more rigorous crash requirements which encourage manufacturers to make cars structurally more stiff. For example, the National Highway Traffic Safety Administration (NHTSA) now crashes cars at 35 mph in their New Car Assessment Program (NCAP). While this is only 5 mph faster than the Federal Motor Vehicle Safety Standard 208 requirement of 30 mph, it requires the car to have to manage nearly 40% more kinetic energy in the crash. The Insurance Institute for Highway Safety has a similar non-obligatory test at 40 mph. In order to perform well on these more challenging crashes, auto makers have had to beef up the structure of the cars. The resulting increase in stiffness means that less energy is absorbed by crushing metal in low speed crashes and more of it is transferred to the occupant resulting in more violent occupant motion and whiplash injuries.
The most common symptoms patients complain of are neck pain, headaches, shoulder and arm pain, numbness and tingling in the upper extremities, mid-back pain, lower back pain, dizziness, forgetfulness, fatigue, visual disturbances, ringing in the ears, movement disorders, jaw pain, neck stiffness, and muscle spasm. Very often the symptoms of these whiplash injuries do not appear immediately. It is not uncommon for the symptoms to be delayed for up to three days. Recent studies have also discovered that persons injured in these kinds of crashes are more likely to suffer from long-term neck and low back pain, breathing disorders, cardiac (i.e., heart) disorders, gastric (i.e., stomach) disorders, and allergies, as well as hypothyroidism. Very often a very mild form of brain injury occurs as a result of the high acceleration of the brain which occurs during the abrupt motion of the head, which can be as high as 12 g in a 7 mph crash. These are referred to as mild traumatic brain injury (MTBI) and frequently result in memory problems, cognitive or behavioral disorders, and mood disturbances.