The practice of seeing patients involved in motor vehicle accidents has earned a dubious reputation because of widespread issues involving insurance fraud. It is a practice that can be very lucrative for doctors and attorneys alike.

One of the more contentious issues surrounding the care of accident victims involves the treatment of patients in accidents that are considered to be in low speed collisions. For purposes of discussion, low speed collisions are those that occur below 20 mph.

Injuries after low speed collisions are contentious for a couple of reasons:

  1. Many of you have probably been involved in a minor accident and walked away without any pain, or had pain that resolved within a week.
  2. Low speed collisions tend to leave the vehicles relatively unscathed. Vehicular damage is a common criteria used to determine the severity of an accident.

Crash Severity Matters, but Not for Everyone

From a population point of view, the severity of the crash is generally related to the significance of the injury. If you have a higher speed crash, you are much more likely to have more severe injuries which makes sense.

However, that doesn’t mean that seemingly minor collisions will leave people injury-free. While most people will be fine, some people will experience substantial problems related to pain and loss of function from accidents as small as 8-9 mph.

Human beings are more than just blocks of bone and tissue assembled together like a machine. There are complex factors in a patient’s history that can make them more prone or resilient to auto injuries. These factors include:

  • Previous history of injury
  • Underlying pain syndromes (headache, arthritis, nerve damage)
  • Physical strength/fitness
  • Psychosocial factors (depression, anxiety)
  • Expectations for recovery

When you combine these factors, along with the uncontrolled factor of chance/luck, then you have an explanation for why one person can walk away unscathed by a 50 mph crash with rollover, and why some can get rear ended at 10 mph and have chronic pain issues.

What Does the Evidence Say

Researchers tend to measure change of velocity and g-force to predict injury.

A paper by Castro et al suggest that the limit of harmlessness for rear end collisions occurs at velocity changes between 6-9mph which seems low enough. In cadaver and model studies, it is estimated that it takes as little as 9 g’s of force to create injury to the ligaments and soft tissues of the neck, with the 15-20 g range being the most predictive for ligament injuries.

While these studies looked at whiplash as a consequence of ligament and muscle damage, the truth is that accidents can also damage the central nervous system. In a similar fashion that hard hits in football can injure brain and spinal cord tissues, the same can be said for auto-accidents.

Contact to the shoulder, head, and neck may not produce obvious signs of tissue damage, but the impact can be enough to create axonal injury along the central structures of the nervous system. Studies on young football players who played a full season of tackle football have been shown to display signs of axonal injury even in the absence of a diagnosed concussion. [Source]

In fact, there is a growing number of studies that suggest that the effects of persistent whiplash symptoms and mild traumatic brain injuries(mTBI) like concussion share similar pathophysiology. [Source, Source, Source]

If that’s the case, then treatment strategies used for whiplash injuries may be useful in the management of specific types of concussions.

When It Doubt, Get Checked Out

Just because you’ve had a low-impact collision doesn’t mean that you can’t get hurt. Especially if you are someone who has a history of neck pain or headaches already, you are likely more susceptible to a neck injury even if the collision seems minor.

If you’ve had a minor collision and you have a new onset of neck symptoms, it’s okay to go and get evaluated by a doctor to see if some conservative therapy can help you.