What Is A Concussion?
If you have recently had a concussion, chances are that you are having a hard time reading this page.
A concussion is often referred to as a minor traumatic brain injury (mTBI) caused by a sudden acceleration, deceleration or blunt force impact to the head resulting in impairment of a complex array of brain and vision functions.
Any sudden movement or bump to your head could cause your brain to move around inside the fluid filled skull and bump up against the inside of the skull. Falling to the front of your head can cause an injury to the back of your brain when your brain bounces back and forth in your skull (a contra-coup injury). We “see” with the occipital cortex in the back of our brain.
At impact, nerve fibers (axons) are twisted and their insulating coat (myelin) is damaged causing a slowing and short circuiting of information travelling along the nerve pathways. Axons will degenerate without myelin and myelin will degenerate without axons. Myelin regenerates in some people better than others. As a result, having a single concussion can cause permanent damage. Having repeated concussions likely results in compounding damage.
When a brain cell is injured by a force, the cell has an initial increase in its sugar metabolism followed by a reduced metabolic state which results in reduced cell function. This accounts for the sense of confusion associated with concussion. Most cells are thought to recover but some cells may die after the injury. Damaged cells have difficulty communicating with each other as electrical charges become poorly regulated and the damaged area has poor blood flow. The calcium and potassium ions that help the cell transfer sugar across the cell wall become out of balance and the cell has an “energy crisis”. The cell stops using oxygen and produces lactic acid. Some cells may recover to their normal function and others may not.
Common Causes Of A Concussion:
- Bicycle accidents / Automobile accidents
- Repeated blows to head (common in soccer, boxing, hockey)
- Sports injuries (especially football / rugby)
- Falls – skiing, skateboarding etc.
Why Are Concussions Dangerous?
A concussion can impact almost every aspect of a person’s life. Anyone who has had one concussion is more susceptible to having another especially within 10 days of a recent mTBI. The long term consequences may include a greater risk for developing dementia, depression and Parkinson’s disease later in life.
- Difficulty with reading
- Difficulty concentrating
- Difficulty with reasoning
- Feeling like you are “in a fog”
- Sensitivity to light
- Blurred vision
- Double vision
- Lack of coordination
- Difficulty balancing
- Slower reaction times
- Difficulty performing everyday activities
- Loss of Visual Field
- Loss of ability to focus and/or maintain focus especially up close
How A Concussion Is Related To Vision
Humans have twelve non-spinal “main nerves” – cranial nerves – that come from the brain. Seven of the twelve cranial nerves are involved in the process of vision. Between 40 and 50 distinct areas of the brain are involved in processing or integrating visual input. You will have visual symptoms if the cranial nerves or if any of the 40 to 50 areas of the brain (including their nuclei or nerve fibers) are damaged. In order to enjoy comfortable vision, our eyes must focus in, turn in and rotate in in a coordinated manner. Having a concussion disrupts this natural coordination and the result is suffering with the visual symptoms that impact daily living. The assessment protocols used to compare these “normal” vs “abnormals” were first published by the Optometric Extension Program Foundation Inc. in 1935.
Therapy That Helps
Any visual activity requires a brain to process information. If a nerve fiber is damaged or lies dormant or inactive, the nuclei served by the damaged nerve fiber atrophies and function is compromised. Stimulating a damaged system attempts to keep the nuclei “alive” and functioning to the best of its potential. Much like in stroke recovery, a brain may reroute the transmission of information along a different pathway in order to regain function. The goal of therapy is to regain normal visual function faster and more completely than with just rest. Stimulating visual activity should also help with cognitive function and a quicker return to symptom free daily living.
How Concussions Used To Be Treated
In the old days people were told:
- to rest
- to slowly return to activity as they felt recovery and
- that it would take about five weeks to recover.
Even though some people might “feel” well enough to return to regular activity, technology has shown that mTBI damage does not resolve for one to seven years after injury and in some cases, it never resolves. Evidence is coming forward to show that having a concussion is a permanent injury and not just an event. While the “rest until you feel better” approach still has validity, today, there is a growing body of thought that intervention and “therapy” to keep damaged regions of the brain active and challenged may be beneficial.
Objectively Measuring Visual Function
Since about 70% of the brain is involved in processing visual information, Visual Evoked Potentials (VEPs) can be used to objectively measure brain function as “normal” or having the characteristics of concussion damage. Regrettably, VEPs are not as routinely performed in Canada as they are in the United States. Our clinic does not yet have VEP but may in the near future. MRIs and CT scans do not detect mTBI but are used to rule out internal bleeding. Gamma ray imaging can “see” concussion damage but this is only used for research purposes.
Vision Testing With A Concussion
Although the symptoms of concussion can resolve over time, trauma can alter the brain’s physiology for years or a lifetime. Different focusing and eye movement tests can measure vision function and hence brain function to know if the vision related nerve pathways are functioning at a normal level or if they are damaged. This information might be beneficial for insurance claims following a motor vehicle or cycling accident especially if you need to prove your symptoms are persisting.
Baseline Testing For Insurance Claims
Having a documented measure of your vision skills (detailed focusing measurements, eye positioning and the range/ability to fuse objects) prior to an injury gives you better protection in the event you need to prove your injury for an insurance claim. Winning an insurance claim without baseline testing can be more difficult.
Note To Athletes
Fewer than 10% of concussions involve a loss of consciousness. If you play football, rugby, hockey, soccer, ride a bicycle to work or on the mountains or if you are involved in sports, you should request a visual skill assessment to establish your baseline prior to an injury. Athletes who have had a concussion can request a visual skills assessment to obtain reasonable assurance that their injury has resolved to their pre-injury baseline (if they had baseline testing) or to the norms of the general population if they have not had baseline testing. Your eye movement (convergence/vergence and adduction) skills are a measure of damage and/or recovery. Without it, returning to activity prematurely may have life-long consequences.
Automobile accidents are a common cause of concussions and often require documentation for a successful insurance claim.
Helping Yourself To Recover
While the physical recovery to an injured brain is time dependent, the visual distress associated with concussion injury is in part a functional problem which can be helped through eye exercises. When you make a functional system work, it learns to adapt and generally reaches its fullest potential sooner than without therapy.