Cervical Acceleration-Deceleration injury in no damage accidents.

on Apr 22 in Chiropractic Blog posted , , , by

Whether or not a person can suffer a cervical acceleration-deceleration injury/whiplash injury (These days we prefer cervical acceleration-deceleration injury or CAD) has been an area of dispute between medical practitioners, insurance carriers and their accident reconstruction experts for over a decade. Cervical acceleration-deceleration injury claims are very common and as such of interest to the carriers, attorneys and medical community as well.

I must admit I have a slight bias against the accident reconstructionists. This started when I was working as a Qualified Medical Evaluator for the workman’s compensation system, I used to field calls from both plaintiffs and defendants asking “Which way do you slant your reports” My response was invariably, “I don’t slant the reports at all, I’m the Joe Friday of the Q.M.E. world, Just the facts Ma’am.” The implication of that question being asked SO many times implies that it is very common for these experts to slant their reports as opposed to reporting the facts but… that’s another article.

The typical way these injuries happen, someone is stopped for a light, or in traffic and someone else just isn’t paying attention. As a result they don’t stop in time, or at all, and collide with the stopped vehicle. Often times in these low speed collisions, when the vehicles are inspected, there is no apparent damage.

Sometimes, someone will get out of the car and state that they have neck upper or lower back pain. Often times these people will actually report pain increasing over the next few days up to a week or so later.

Which brings us to the first fallacious claim of the carrier. With no damage to the car, there can’t be any injury. As a matter of fact, when the car crumples in an accident, the body of the car is actually absorbing impact energy by crumpling. When the car doesn’t crumple, all the energy of the impact is transferred to the passenger compartment. If we remember our physics, mass times velocity equals force. So if a 2000-pound car is moving 2 miles an hour the force of impact is 4000 pounds. I think its safe to say that this amount of force is more than a little tap even if there is no damage to the car.

There are impact studies that indicate it takes speeds of over five miles an hour to cause damage to a car with our current impact resistant bumpers. There are also studies that indicate the forces that transfer to the head of the vehicles occupants are two and a half times that of what impacts the vehicle and that this transfer of energy takes place in a quarter of a second. Let that sink in for a quarter of a second will you?

How does one get a cervical acceleration-deceleration injury?

What exactly happens in one of these low speed impacts? I’ll present here a somewhat simplified version. As the vehicle is struck, the bodies of the occupants accelerate forward, the head being of smaller mass than the torso, has a lag in its forward movement that hyperextends the neck causing stress on the anterior ligaments of the neck. The torso then impacts the seatbelt bringing its forward motion to an abrupt halt (Deceleration) yet this time, the head shoots forward propelled by the momentum of its own weight. (Think of it this way, the head ways about twelve pounds, the neck is about six inches long so… its like a bowling ball on the end of a six inch lever.) This abrupt stop, causes the posterior ligaments to become stretched as the neck goes into flexion. But wait, sometimes the fun doesn’t end here, the body slaps back into the seat, knocking the head back against the head rest again causing a strain to the anterior ligamentous structures. All of this takes place in milliseconds however, I hope as I describe the mechanics of this to you, you can comprehend how it doesn’t take a lot of force to cause serious soft tissue injuries. I am also sure when you think about the mechanics, you can see why we prefer cervical acceleration-deceleration injury to the term whiplash. Its a more accurate explanation of what happens.

Other factors that have to be considered in analyzing these situations are, the overall health of the victim whether they are sedentary or athletic. Whether the headrest was high on the back of the head, or lower at the base of the skull. Whether the vehicle occupant was aware of the impending collision, bracing for it or relaxed, and did the person have any preexisting conditions that may further contribute to the persons level of injury such as head forward posture or a reverse cervical curve. Each of the above could be a stand-alone article but lets just say it appears that the carriers and their experts don’t see any of the above as an issue.

One of my favorite carrier arguments was a letter to an attorney stating, “Our experts have determined a normal healthy person could not have been injured in this accident based on the damage to the vehicle.” In that case the healthy person to whom they were referring was a sedentary, six foot two, three hundred forty pound woman with a reverse cervical curve (Neck bent the wrong direction), who at the time was driving a minibus. The car that struck the bus however was totaled but the bus had only a small scratch. Yup, she sounds normal and healthy.

The next fallacious thought process that seems to come into play; if the person has no overt (External) signs of injury they cannot be hurt. There are numerous studies that state ligament damage can and does occur in these situations. The damage can cause chronic pain that lasts up to a year or may in fact be permanent. Ligaments are avascular and as such do not heal like other tissues due to their lack of blood flow. Another issue is that it may take a day to a week or more for the altered range of motion to become apparent. When the body starts to deal with this, part of the healing process is the deposition of scar tissue around the posterior facets of the spine which then causes asymmetrical range of motion. There is also a “Guarding” mechanism, which is the body developing spasm as a method of preventing further damage from occurring. This spasm itself causes a chronic pain and the resultant inflammatory response exacerbates the entire complex. So yes, there is a lot of scientific and medical evidence that minor fender benders can cause rather serious injuries. Cervical acceleration-deceleration injuries are real and can have a significant impact on the enjoyment of life on people who have had one.

Clearly it serves the carriers best interests to downplay the nature of whiplash (CAD) and they tend to imply two things in theses situations. The next two fallacious though processes I’d like to address.  The first is that the patient is faking this to get time off from work, lightened workload, or…. Rich off the ill-gotten gains, Part of that thought process involves the medical provider being in collusion with the patient for an extra buck, and if an attorney is involved they too are part of the fraud.

I can see how the public or a jury could be suckered into this idea, and I am not saying this NEVER happens, however let me give it some perspective. Believe me when I tell you, its not fun to go to the doctor for repeated treatments. Yes I know, I’m a really charming and fun guy to hang around with, but my treatments are often spoken of as “It feels much better when he stops.”

The second reality check, attorneys don’t want to take on cases where they invest time and monies that they don’t think they can win. Therefore most attorneys seriously vet their clients and have to believe they are sincere or they don’t want to get involved.

The third reality check, Chiropractors, Doctors, and Attorneys have these things called licenses. They are very expensive and time consuming to obtain. What kind of professional smart enough to earn such a degree would risk their license, reputation, time, and in fact career to gain a nominal amount of compensation on any single case?

I hope from the information I’ve presented above, you understand that it is not only possible, but actually likely that whiplash (CAD) injuries take place in low speed rear end collisions with no damage at all to the car itself.

It is also likely that based on the relative health of the occupants not all of them will necessarily be hurt to the same degree. The last fallacious concept I would like to cover in this less than brief article. When friends or family who have been in these situations turn on their loved ones because “I ain’t hurt and I was in the car too.”

Its sad to see and seen it I have, someone with a preexisting condition be chastised by the other people in the vehicle simply because they themselves didn’t suffer any long lasting effects of these low impact collisions. Can you imagine how it must feel to have a friend or family member doubting your pain because they themselves were not similarly affected in the same situation?

I hope this has provided some food for thought, as always, thanks for reading.

For more information on this topic: Auto accidents low speed impacts