Biomechanics of Concussion – Illustrative but Not Definitive

Biomechanics of Concussion –

An Insufficient Explanation

By Gordon Johnson

Call me at 800-992-9447

Though titled the Biomechanics of Concussion, this treatment will not try to provide a formula to answer the root biomechanical question:

“Was there sufficient force to cause brain damage?”

Mechanics is the field of engineering that applies the principles of engineering, physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems.  Biomechanics is the sub-field of mechanical engineering that analyzes those principles to biological systems, such as the human body. The biomechanics of concussion uses engineering principles to understand how the brain is impacted by the application of trauma and force to biological tissue.

Not even in a laboratory, can biomechanics tell us how much force on the brain is too much.   In the real world, it would be impossible.  What biomechanics can do is help us understand what mechanical forces could possibly have injured the brain.  Biomechanics, however, cannot rule out brain injury.  We simply do not know enough about the lowest threshold of force that a human brain endure.

Engineering explanations deal with generalities. The theory of the biomechanics of concussion allows for precise calculations based upon  imprecise assumptions of what happens in a non-laboratory trauma.  While the biomechanics of concussion can help us overcome the natural skepticism that something so seemingly trivial can really be quite devastating, they do not explain the individual differences.

Virtually all those who suffer a concussion have the potential for life altering changes in the way their brains function.  Still the vast majority have “apparent full recoveries”, as did I. The “why” is hard to completely explain.  But what should not be hard is to is diagnose those who don’t get better.

The reason for mistakes in diagnosing concussion is the ground clutter of “objective” diagnostic tools upon which our doctors have become foolishly dependant.  The diagnosis of brain injury cannot be ruled out by imaging studies, Glasgow Coma scores or an analysis of the biomechanics of concussion. We simply cannot accurately measure the biomechanical forces of a real world trauma, after the fact.  Even neuropsychological testing cannot rule out brain damage.  Diagnosing brain damage after a traumatic injury requires the following:

To look thru skin, skull and tissue, to see a mixture of pathology involving damage to:

  • Structures,
  • Blood vessels,
  • Microscopically thin axons, with macroscopic length,
  • Microscopic damage to nerve cells, and
  • Changes in brain chemistry,

Proof of pathology which is often “invisible” can only be done by an examination of how the brain’s function has been changed – in the real world laboratory of life. The professional who demands an objective technological test to make a diagnosis – will always get it wrong.   While certainly objective measures of real world mind dysfunction exist, the depth and the specifics of the problem are going to be unique. Only after an experienced professional has evaluated the facts and circumstances, can a diagnosis be made. That diagnosis must by definition be subjective.

Sadly, there are far too few doctors, whether M.D. or Ph.D., who have sufficient expertise and wisdom to fully comprehend the subtleties of this diagnosis of concussion and the courage to make it. Only through a comprehensive evaluation of the subjective, real world change in a person’s ability to function, can meaningful diagnosis be made.  Understanding the biomechanics of concussion can help.  But only for ‘ruling in” the potential for significant injury after concussion, not by “ruling out” such injury.

Next – Concussion Story Continues

I use the term “apparent full recovery (ies)” because significant research has shown that when the brain is tested at its limits, even those with “apparent full recovery”, do significantly worse than those without a history of concussion.  See Dorothy Gronwall’s PASAT altitude study.


Gordon Johnson

Attorney Gordon Johnson is one of the nations leading brain injury advocates. He is Past-Chair of the TBILG, a national group of more than 150 brain injury advocates. He has spoken at numerous brain injury seminars and is the author of some of the most read brain injury web pages on the internet.

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