Actual

Questions and Answers

concerning the

"Whiplash-injuries"

Answer:

You asked me about the mechanical properties of the brain tissue. When reading my report you'll see I have only described the principals of how live organic materials will be affected by the forces during such an event.

I have had no possibility to find the properties of the tissues itself and it's far beyond my professional competence to do so. I think this has to be done by pathologists, but it looks to me as a very difficult task. I can neither tell how large deformations structures as the brain tissue can stand before damages will occur.

I have been searching for factors making parts of the body vulnerable to the affections in the "WL" and I mean I've really found it.

To consider the vulnerability of the brain you have to make a study of the mechanics on a macro level, considering how the axones, and their myelin covers as well as the connections between the axones and the next brain cell, the synapsis, are affected in such an event. The mechanism will give both a pressure between the scull and the brain combined with a rotation giving stretching and shearing loads towards that structure. I think the limits for when damage will occur to such a structure will be low compared with the acceleration which occurs in car accidents. In even the lowest velocity rear-end collisions the acceleration of the head might be at 5 to 6 times g (i.m. 6 times the acceleration of gravity (g) and approx. 2 to 3 times the maximum acceleration of the car) increasing to 100 g in a very tough front collision. The mechanism affecting the brain is described in my compendium, Chapter C2.

The research done by Ommaya and Generalli at The National Institutes of Health, Bethesda, Maryland USA,1975 refers to acceleration tests applied to primates 1968, showing injuries in the affected areas of the brain at an acceleration of the test carriage at 2 g and an acceleration of head of approx. 5 g.

In the linked sites you'll find reports indicating crushed brain structures as a result of "WL", as they find in severe head damages where the scull are crushed, without any external damage of the head or scull. These are just the kind of injuries I will expect from this kind of mechanism. The damages caused during the slow down of the head in front might be increased both because of the safety belt and even because of a neck support giving the possibility of a higher forward velocity of head than without.

Answer:

When the effects towards the neck and the effect towards the head and the brain including the medulla are considered as two different mechanisms they are based on a misunderstanding of the mechanisms in a "Whiplash".

In fact this kind of mechanism includes a wide range of affections of the back, the neck region as well as the head and the brain itself. Where and how the different parts of the body are affected and how large such an affection causing forces and movements affecting different parts of the body will be, depends on a great number of factors, including how the person is seated, the awareness of the person, the seat structures, the difference in the velocities and the weights of the cars involved etc. If no other mechanisms occurs, such as direct acting forces towards the head as the head hits the front screen or any other objects of the car, all effects are caused by the same kind of mechanism, the "Whiplash" mechanism. Whether or not it has been a large inclination of the neck are of minor interest when considering the loads towards the brain.