Elizabeth Concludes with – The Puzzle of Mild TBI
Elizabeth’s story exemplifies the all too common occurrence of a second less severe injury (i.e., concussion) producing a greater disability than an earlier more severe brain injury (i.e., coma and brain surgery). This segment explores possible explanations. Elizabeth’s speedy recovery from her first severe injury undoubtedly occurred in part from a phenomenon known as plasticity. Plasticity is the ability of one brain structure to take over functions normally performed by another brain structure. While this is an amazingly positive feature of the brain, the downside is that brain efficiency operates at a reduced or slower level. A helpful analogy is to think of different parts of the brain as stores in your neighborhood which take care of different needs. If some of these stores were to close one day, one would have to drive farther to stores located in outlying neighborhoods.
Concussions, on the other hand, typically cause injury to the brain’s axons, a structure which allows brain cells to communicate with each other. Expanding on the previous analogy, this would be like traveling on roads that are torn up or closed off. Traveling long distances to stores in other neighborhoods on roads that are torn up or closed off is the equivalent to recovering from a severe brain injury and adding a less severe brain injury to the mix. If one tries to travel during rush hour, the equivalent of stress, noise, pain, or crowds, traffic shuts down….the brain stalls because of too much demand on an inefficient operating system.
Another possible piece to this puzzle involves the hippocampus and amygdala, two brain structures located deep within the brain, and how they communicate with the frontal lobes. The hippocampus plays a major role with short-term memory, and the amygdala plays a primary role with our emotional reactions and can override other brain functions by giving priority to emotions over memory. The uncinate fasciculus is a tract of axons which connects the hippocampus and amygdala to the lower part of the frontal lobes. This particular connection of axons is particularly susceptible to injuries from concussions where the brain tissue twists. We hypothesize that the uncinate faxciculus’ reduced ability to communicate effectively with the lower frontal lobes can increase anxiety and turn into either an anxiety or panic disorder. As anxiety increases, memory decreases. Unfortunately there are no electronic devices which can diagnose damage to the uncinate fasciculus; such identification relies upon clinical judgment. Elizabeth’s statement about “…snapping with…stress, nerves, fear,” highlights the uncinate fasciculus’ role in how fear, anxiety and memory are processed in the frontal lobes.