Brain injury susceptibility
1. The Frontal Lobes Are Very Susceptible To Traumatic Injury.
The brain has to halves or hemispheres and each has a frontal area behind the forehead known as the frontal lobe. The frontal lobes are the largest of the four lobes of the brain and they are what make us uniquely human. The frontal lobes are responsible for “executive functions” such as memory, reasoning, information processing, concentration, organizing, planning, decision making and judgment.
Another way of looking at the frontal lobes is that it is the area of the brain that makes you who you are as a unique individual. Injuries to the frontal lobes often completely change the personality of the injured victim. One former client described the frontal lobe injury to her son’s brain as follows: “We sent Johnny to camp one day, and he never came back”. Of course, Johnny physically returned but his severe frontal lobe injury destroyed his former self. The frontal lobes are often defined as the area of the brain that make you, “you”.
The frontal lobes are particularly susceptible to injury due to the acceleration and deceleration of the jello-like brain which lives inside a hard skull. The brain is packed with blood vessels to bring oxygen laden blood to its nerve cells. These blood vessels are sensitive to trauma and when the brain is propelled into the skull from head impact or extreme head movement, the blood vessels are disrupted and there can be bleeding.
This is referred to as a coup-contre-coup injury. “Coup” means blow in French and the animation shows how the brain moves within the hard skull when it is propelled forward from deceleration or impact from the rear. The point is that although the original impact or “coup” may be at the rear of the skull, the “contre-coup” or rebound injury is the compression of the frontal lobes at the front of the skull as they contact the rough and uneven interior surface of the skull. This secondary impact with the neighboring skull is what causes the damage to the frontal lobes.
If the impact is severe enough it will cause bleeding and/or brain swelling. Remember that the brain is confined by a very strong bony skull. There is no room for swelling and there is nowhere for accumulating blood to go. This puts pressure on the rest of the brain, cutting off circulation of blood and oxygen leading to brain death known as encephalomalacia. Encephalomalacia shows up on brain scans as a dark, void area meaning that the brain is gone . Intracranial (inside the skull) pressure can be fatal unless something is immediately done about it. These injuries are permanent because brain tissue does not grow back.
In recent years neurosurgeons have started relieving intracranial (inside the skull) pressure to the brain by removing part of the skull so the brain can “pooch out” like a mushroom beyond the skull and heal. This surgery is called craniectomy (removing the skull). It has had dramatic results in saving the lives of brain injured victims. As the brain heals it retracts inside the skull and then the skull piece can be replaced or an artificial piece of skull (prosthesis) can be inserted. This surgery is called cranioplasty. Craniectomies are used for injuries to other lobes but the frontal lobe is the most vulnerable to injury.
2. The Prefrontal Cortex (PFC) Is The Most Susceptible Region Of The Frontal Lobes To Injury.
Neuroscientists divide the brain into areas for study. This is called cytoarchitecture of the human cortex. These brain regions are given numbers and are referred to as Brodmann areas (BA).
The prefrontal cortex is very front or anterior part of the frontal lobes and is located immediately beneath the forehead. The “pre” is probably a misnomer. It is the frontal cortex and it has been referred to so long as the prefrontal cortex that the term has stuck. It is the control center for human executive functions.
The PFC includes BA 8-13, 44-47. Doctors describe the areas of the PFC by using terms like dorsal (top), ventral (bottom), lateral (outside), medial (inside), anterior (front) and posterior (rear). They also use other acronyms to describe its geography like rPFC (rostral means near the nose and mouth), dPFC (dorsal PFC), vPFC (vental PFC) and any combination of directions like dmPFC (dorsomedial PFC). See illustration above.
Executive function relates to the ability to differentiate between conflicting thoughts, working towards a defined goal and social control (the ability to suppress urges that if not suppressed could lead to socially unacceptable behavior). Another way of looking at suppression is that a normal PFC is a “filter” that allows a person to act in a socially acceptable manner. If the PFC is injured or its atrophies with age, the filter can disappear and then socially unacceptable behavior becomes the norm. Neuroscientists are trying to use fMRI to isolate areas of the PFC that are responsible for certain executive functions.
The seminal case regarding PFC function was the case of Phineas Gage. Believe it or not, one or both of his frontal lobes were destroyed when a railroad spike was accidentally driven through his head in 1848. Photos of Mr. Gage and the spike are below:
See Phineas Gage photos below:
It is reported that despite the injury he retained his normal memory and his speech and motor skills but his personality changed radically. He became irritable, quick tempered and impatient. His friends thereafter described him as “no longer Gage”. Also, although prior to his injury he was a very efficient worker, afterwards he could not finish a task. This is a prime example of the phenomenon that often occurs after a TBI. The person looks normal but he is no longer the same person because he has sustained an injury to his PFC.
This should not be confused with normal teenage behavior. Brain cells in the PFC form connections more slowly than in any other area of the brain. Anyone who has raised a teen knows about typical teenage behavior (slamming doors, mood swings, rash decisions etc.). Parents often blame hormones for this behavior but it is a product of the undeveloped teenage brain. A teen’s PFC is incapable of the kind of decisions adults make. They have underdeveloped decision processing centers: wrong food choices, risk taking (drugs and alcohol) etc. The PFC does not mature until a person reaches his 20’s and it is known as cognitive maturity. Teens simply cannot resist the impulses they feel due to their undeveloped PFC. Of course, an injury can mimic the same behavior.
To conclude, injuries to the PFC portion of the frontal lobes can cause the following symptoms:
- Reduced drive
- Mood changes (Emotionally Labile)
- Personality changes
- Memory deficits
- Impaired information processing speed
- Reduced judgment
- Increased impulsivity and disinhibition
- Uncharacteristic lewdness and cursing
- Difficulty with problem solving
- Loss of flexibility in thinking
- Problems with interpersonal behavior
- Loss of spontaneity in interacting with others
- Reduced attention
- Inability to focus on task (Attending)
- Persistence of a single thought (Perseveration)
- Inability to express language (Broca’s Aphasia)
- Increased aggression
- Inability to plan properly and execute those plans (Executive Function)
- Increased disorganization
- Inability to plan a sequence of complex movements needed to complete multi-stepped tasks (Sequencing)
- Altered sense of smell (Anosmia)
- Loss of simple movement of various body parts (Paralysis)
- Diminution of attention to personal appearance and hygiene
3. Sporting Activities Present A Risk Of Frontal Lobe Injuries.
Participants in certain sports routinely wear helmets and in others they do not. For example, helmets are common in bicycling, motorcycling, motocross, football, lacross, and skiing. However, helmets are no guarantee of head injury prevention for the reasons stated above. Most of these helmets if properly sized, worn and adjusted will prevent skull fractures but they do not prevent the brain from moving inside the skull. The concussions or coup-contre-coup injuries can still occur. It all depends on the forces involved.
For example, it has been reported that there are 50,000 bicycle related brain injuries per year with over 400 deaths. Helmets are the best way to prevent serious brain injuries and can reduce the severity of brain injuries by 85%. Abramson Smith Waldsmith recently represented the family of a helmet wearing man who was hit by a truck mirror while riding on the white line of a bike lane when he was going 35MPH. When he lost control of his bike and stuck the ground, he sustained a major injury to his frontal lobes and he died within 24 hours. The helmet did not prevent this injury.
Football helmets also do not prevent brain injury although they seriously reduce its occurrence. Concussions from impact are still a problem at all levels of the game. The studies have shown that repetitive head injuries increase the risk of neurodegenerative diseases later in life like premature senility, Alzheimer’s disease and Parkinson’s disease. Lineman are particularly at risk due to the frequency of their head to head contact.
No helmets are worn in the popular sports of soccer and rugby but there is ample risk of head impact and potential TBI. It has been reported that approximately a quarter of all rugby injuries involve serious concussions. Studies have been done on soccer players and the risk of TBI from “heading” the ball. It has been estimated that a soccer ball kicked at full force can collide with a player’s head with 175 pound of force. Doctors have recommended that children under 14 should not do headers due to the risk of TBI and damage to the frontal lobes.
A Norwegian study of active and former national soccer team players investigated the incidence of head injuries from heading. One third of the players had evidence of TBI including mild to severe deficits in attention, concentration and memory. The players who headed more had higher rates of cognitive loss. In 1998 Dutch researchers found the same thing.