Many experiments have been done to determine if brain injury could occur without actual head impact, according to studies. An impact injury that deforms the skull may have some sort of mitigating factor because the skull distributes some of the force that would have otherwise been transferred directly to the brain, similar to the way a motorcycle helmet protects the head of the motorcyclist.
Non-impact generally means the head did not suffer a direct impact. The distinction is important to both forensic physicians and brain doctors. There have been a number of child abuse cases where the defense alleged brain damage was caused to infants by being shaken, rather than being struck by, or against, an object. Some studies have shown that shaking the torso of an infant was unlikely to harm the brain of the child, apart from a blow to the head. This is consistent with research from car crashes, which shows that force that comes from the torso to the head is unlikely to cause harm, even with the much greater force involved in a car crash.
Mathematical models in Nassau and Suffolk have been used to simulate the human body, in order to show how likely it was for injury to occur with differing impacts in a car crash. They tend to conclude that acceleration of the head is unlikely to reach a level that could cause brain injury, studies have learned. In a previous study of 400 fatally injured road users, there were no cases of brain injury without head impact.