Prior Combat Stressors Adds One More Trap for TBI

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Posted on 18th June 2010 by Gordon Johnson in Uncategorized

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In our last blog, we introduced the reader to the potentially disastrous combination of TBI and PTSD conditions in a combat survivor. But the problem in combat is not just the intersection of these two “co-morbidities”, but the likelihood that a third complicating factor- preexisting anxiety – will also be found in combat veterans.

As we outlined yesterday, the Limbic System is the part of the brain which regulates anxiety and memory. Just as the corpus callosum is the collection of axonal fibers that connects the two hemispheres of the brain, the uncinate fasciculous is the collection of axonal tracts that connect the principal memory and anxiety centers of the brain to the frontal lobes – the thinking and maturity parts of our brain.


The principal structures involved include the following;

Hippocampus. The brain’s save button is the hippocampus. It is the part of the brain most important to converting immediate memory to long term memory.

Amygdala. The brain’s anxiety center is the amygdala. It is the amygdala that protected us from predators in the pre-historic times. It triggers our startle reflex in modern times and is the principal culprit in anxiety disorders.

Frontal Lobes. The frontal lobes are where we learn to become adults, where all activity is initiated, decisions made, emotions modulated and judgment’s made. The orbital frontal part of the frontal lobe, on the underside, is essentially the conductor of the brain’s symphony, the part that tells the other instruments when to start and stop playing. The frontal lobes coordinate all activity.

Uncinate Fasciculous. Connecting the above critical structures is the uncinate fasciculous, the axonal tracts that run from one end of the lower brain structures to the underside of the frontal lobes.

A person with a pre-injury anxiety disorder is far more vulnerable to post concussional problems (PCS). In a person with an anxiety disorder, the amygdala is already overreacting to potential anxious moments. It runs “hot” so to speak. When, as a result of trauma, such as a blast, damage occurs to the hippocampus, frontal lobes and the uncinate fasciculous, the information that gets moved across this lower brain circuit gets garbled. When information between the limbic system and the frontal lobes gets garbled, anxiety can become panic, depression can become organic rather than just reactive and the person’s ability to modulate emotions and make decisions, seriously impaired. The combination of pathologies in these areas -coupled with inefficient communication between them – creates a synergistic pathology far more functionally impairing than any one of those impairments might have been alone.

As serious as this premorbid vulnerability is in a civilian, it is far more serious in a soldier. Think of it this way. The amygdala is there to get us to run, without stopping to think. Fortunately for peace time activities in the modern world, our socialization has taught us when not to panic. A civilian has few times when he or she needs to rely on the amygdala. There are few great predators, few brushes with real danger. Thus, our frontal lobes and other emotional centers have tamed our amygdala, in not so different of a way than we tame a pet.

Yet, the amygdala is needed for combat. To survive, a soldier must rely on his instincts and must put his mind into a hypervigilant state. One of the biggest problems that soldiers have reintegrating into civilian life is learning how to stop this hypervigilance. PTSD is primarily a disease where the traumatic emotional stress has so changed the amygdala that it never entirely goes back to its peace time role.

Thus even before a TBI, a combat veteran is likely to have a heightened anxiety. Without that anxiety- the hypervigilance – the soldier may not survive. Depending on the level of previous battle stresses, that anxiety may have elevated itself to PTSD levels prior to the TBI. Thus, the risk of emotional dysfunction is not only increased by the very battle in which the soldier is injured, but also by the pre-injury emotional state.

The irony of all of this is that this convergence of co-morbities is laid upon those we expect to be the toughest. “The Few, the Proud” are those at greatest risk of becoming the homeless, the disturbed, the arrested. Sadly, I can offer no solution other than peace.


D-Day and Second Impact Syndrome


Posted on 16th June 2010 by Gordon Johnson in Uncategorized

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Yesterday, we talked about the practicalities of TBI and combat. Perhaps the best way to visualize those practical problems is to watch the opening scenes of the movie, Saving Private Ryan.  A clip of the first 10 minutes can be found at YouTube here: At eight minutes into this clip, the lead character, Captain John Miller, played by Tom Hanks, is near a mortar or artillery shell which explodes upon the Allied troops as they land at Omaha Beach.  Captain Miller clearly suffers a concussion in this blast without any apparent loss of consciousness.

The next minute of this clip is the most honest treatment of concussion I have seen from Hollywood.  Captain Miller struggles to his knees, helmet in hand.  For the next minute he does nothing, seemingly unable to comprehend that he has been hurt, that he is in combat, that he should put his helmet back on.  In almost a childlike gaze, he takes in the horror that surrounds him. His hearing, his balance are impaired.  The viewer gets the sense of this because Director Steven Spielberg cuts all sound, the viewer, like the concussed soldier becomes deaf. Captain Miller, as we watch in horror,  does virtually nothing to defend himself, despite the cataclysm which surrounds him. After 90 seconds, his thinking clears and he regains his ability to command.  He is able to save his life, those of most of his troop and Private Ryan.

This portrayal of concussion by Hanks may be fictional, but it is a classic example of art showing us what is real.  Hanks and director Spielberg have gotten this just right, at least in the acute stage of the concussion.  What I believe is most important about this portrayal of concussion is that it demonstrates the combat challenges in avoiding second impact syndrome and simultaneous PCS and PTSD.

Second Impact Syndrome. The big impetus for the sport and concussion movement that has so changed how the world views concussion, was a 1991 description of the “second impact syndrome.  See Kelly, JP, JAMA.  1991 Nov 27;266(20):2867-9.  “Concussion in sports. Guidelines for the prevention of catastrophic outcome.” The concern in second impact syndrome is that a concussed brain is no better at defending against a catastrophic increase in brain blood pressure, than the Captain is in avoiding bullets.  For the sake of illustration, the brain becomes confused as to how to regulate its blood pressure by the first concussion.  When the second impact puts an added strain on such regulatory apparatus, the brain has no remaining defenses.  Death or severe injury results.

What makes second impact such a practical problem in combat is the increased risk of second concussion because of the disorientation and confusion from the first concussion.  While such is also true in sports, the risk factors of the second injury are so much greater in combat. No injury timeouts in combat. As you watch Saving Private Ryan, you realize how vulnerable a soldier with a 90 second disorientation is.  He is in the line of fire, without his helmet, completely confused as to what to do, what has happened. There is probably nothing we can practically do to reduce the risk of the contemporaneous second concussion in combat. But what me must do is make sure we don’t send the soldier back into a combat zone in the days and weeks afterwards. That is where battlefield screening would be so important.p>

Interplay Between Concussion and PTSD. While the science in this area is still evolving, I am completely convinced that Post Concussion Syndrome (PCS) has as its core problem, a compromised attentional capacity.  When compromised attentional resources are combined with emotional stressors (of which combat based PTSD would be among the worst) the likelihood of a disability multiplies.

The least understood but potentially most serious pathology after a mild traumatic brain injury  (MTBI) is compromised brain signaling between limbic structures like the amygdala and hippocampus and the frontal lobes.  Communication in the brain is electrical, with the electrical impulse being carried from one neuron to another down axons.  Fiber tracts are the bundles of axonal fibers that connect one part of the brain to other part of the brain or to the nervous system.  See One of the most exciting new developments in the last decade is the capacity to see damage axonal tracts on MRI through the use of Diffusion Tensor Imaging (DTI).   Even though axons are far too small to be seen on MRI, DTI can see the cumulative effect of axonal injury because of its ability to see an interruption in the fiber tracts.  See

Unfortunately, not enough DTI research is being done on what I believe to be the biggest culprit in PCS, the uncinate fasciculus. The uncinate fasciculus is a fiber tract that connects the limbic system to the frontal lobes. Add structural injury to either the limbic or frontal lobes to damage to this fiber tract and the brain dysfunction can  hit critical mass.

One issue this week  has been what the Pentagon has done with the $1.5 billion that has been spent on TBI.  I can categorically say that if war is anything like Saving Private Ryan, the U.S. military owes it to its soldiers and Veterans to prioritize research into the limbic system, uncinate fasciculus and frontal lobe injury.  Lt. Col. Michael Russell, head of the Army’s ANAM program says there are too many “false positives” for TBI when administering the test mandated by Congress.  One of the reasons there are so many  is that the emotional stress of combat alone could impact the brain’s panic and emotional centers.  Add diminished attentional capacity and compromised axonal tracts which arise from MTBI and the risk of a catastrophic result will still be there when the bullets stop flying.

Too Many TBI’s, Not Enough Soldiers


Posted on 15th June 2010 by Gordon Johnson in Uncategorized

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Our blog yesterday about the Pentagon’s failure to follow through on mandatory testing for brain injury raises numerous issues worth commenting on, including the military’s outright failure to follow orders, the superficial approach to the diagnosis of brain damage and the magnitude of the problem that is being pushed on down the road to the next generation.  Yesterday’s blog is here:

The generals in essence are telling Congress that if they properly treated soldiers for TBI, there just wouldn’t be any soldiers left.  They use the term “false positives” but that is really short hand for saying that too many soldiers are showing symptoms to treat them all.  And frankly, the problem isn’t really the cost of treatment or even the availability of treatment facilities, although the second part of that could certainly get to be an issue.  The problem is that if they followed anything close to the protocols for treating athletes with concussions, there might not be anyone left to fight the wars.  You see, if we were talking athletes, we wouldn’t allow them to go back into the field until they were completely cleared of Post Concussion symptoms.  Our military is already scrambling to find enough soldiers to fight two wars.  Put any more on the sidelines and we would have to change our foreign policy.

While I may be one of the few civilians who fully understands the true implications of “no return to play” for soldiers, didn’t we promise to do better with this war?  I have been blogging about the Nightmare of War Time Brain Injuries since (read bottom up) and specifically since

This problem with combat TBI is not a new problem.  German, Japanese, Korean and Vietnamese artillery and mortars were far more potent than road side bombs.  And while it is true that we are saving more severely wounded TBI soldiers, the mild and moderate survival rates are likely unchanged since World War I.  What is different is that we have the capacity to diagnose MTBI now and we are supposed to care, because Congress and the American public says so.

The problem isn’t too many false positives.  It is too many positives, too many soldiers with brain damage.  It has always been true, since the day of the club and it will always be true – combat is hard on the brain. That is why  the helmet was invented.  What we as a society have to accept is that if we are truly to “be there” for our troups, we must pull them out of the field when they get a head injury.  That means we either have to have more soldiers or fewer military ambitions and then apply all of the best medicine to help them when they do suffer a TBI. If we don’t, the correlation between soldiers, homelessness and suicide will be the same in 2050 as it was in the 20th century.