Author: Dr. Graham Berg
Concussions can be pretty scary. They can affect everything from speech and memory (both short and long-term) right down to movements and social behaviors. The mayo clinic defines a concussion as “a traumatic brain injury that alters the way your brain functions. Effects are usually temporary but can include headaches and problems with concentration, memory, balance and coordination.”1 Think of your skull like an egg – a hard shell on the outside with the yolk (or your brain) on the inside. Eggs are obviously much more fragile, but if you shake an egg you can feel the solid mass of yolk moving inside. If you hit your head or shake your body hard enough, your brain will move around in the liquid surrounding the brain called cerebrospinal fluid. If the impact is strong enough the brain will push against the hard surface of the skull leaving a “bruise” on the brain. This is the starting point of a concussion.
The damage that occurs from a concussion is dependent on the location of the “bruised” section of the brain. For example, trauma to the back of the skull will likely cause damage to the occipital lobe (responsible for vision) located in the back part of the skull as well as the frontal lobe (responsible for learned movement and a large variety of tasks) and various areas in between as the brain bounces off the inner walls of the skull. For this reason and due to the complexity of the brain, it is very difficult to predict problems that will ensue from a concussion.
There are two main conditions which affect visual processing after a concussion; post trauma vision syndrome (PTVS) and midline shift syndrome (MSS). Post trauma vision syndrome is the most common and easiest to understand. The major problems associated with PTVS have to do with how well our eyes work together (binocular vision). The trauma often causes the nerves responsible for the eye’s movements to “misfire”. This results in binocular vision problems such as, but not limited to exotropia or exophoria (eyes turn out), accommodative dysfunction (poor focusing mechanism), vergence dysfunction (problems converging and diverging the eyes), or general oculomotor dysfunction (poor eye movements). The patient may develop symptoms like double vision, print moving on a page, headaches, problems with balance, eye strain/fatigue (asthenopia) as well as other symptoms.
In order to help comprehend midline shift syndrome (MSS), imagine if a person’s two eyes were averaged out and formed one eye roughly in the middle of the forehead (picture a cyclops!). This theoretical eye is what your brain constructs from all the input from your two eyes. When trauma occurs this theoretical eye can sometimes shift to the left, right, forwards, backwards, or any combination thereof. This can then throw off a person’s balance, gait, and proprioception. Through the use of prisms and other physical therapy, the theoretical eye can be pushed back to its natural spot prior to the injury.
There are different forms of therapy available depending on findings from the initial assessment. If you or someone you know is suffering after a concussion feel free to book an appointment with Dr. Berg so he can help with the appropriate treatment.
1. http://www.mayoclinic.org/diseases-conditions/concussion/basics/definition/con-20019272 accessed on March 7, 2016