While a thorough neurological history and examination with a qualified professional should be performed for any suspected head injury, particular emphasis should be placed on the cranial nerves – the nerves that exit your brain and brainstem. Of these cranial nerves, the most telling findings will likely come from the ones involved in vision and eye movement (cranial nerves 2, 3, 4 and 6). It is also critical to assess higher brain centers that control various eye reflexes, which will be discussed later in this article, during the eye examination as well.
There are many types and causes of head injury, but, by far, the most common are concussions related to motor vehicle accidents and contact sports. Concussion comes from the Latin ‘Concutere’, which means to shake violently. Most experts would agree that these are the least serious type of brain injury; yet left untreated many can suffer devastating and debilitating consequences such as vertigo/dizziness, balance problems, cognitive dysfunction, emotional disorders, headaches, and many others.
Given concussions are ascribed this ‘low severity’ status, timely evaluation and treatment is often poor or non-existent at best. Patients are often treated with a ‘sit-and-wait’ approach; meaning it is only after signs and symptoms have manifested and worsened that people often seek care of their own accord. This is entirely unacceptable as early intervention is critical with concussion, as is the case with most disorders of humankind, and it may significantly decrease the likelihood of more serious consequences. The longer one’s brain is adapting to negative changes incurred as a result of a head injury (referred to as maladaptive plasticity), the longer it will take to rehabilitate their way out of them!
Shifting our focus back to the eyes (pun intended); most individuals that have suffered a concussion will complain of some type of symptom related to eye function (e.g. blurry vision, light sensitivity-photophobia, eye fatigue, double vision-diplopia, reading difficulties, etc.). I cannot honestly recall a single case of concussion presenting to my office in the recent years that did not have some type of visual or oculomotor (eye movement) consequence.
We have all seen at some point on TV or the ‘Big Screen’ a doctor shining a light in someone’s eyes to look for lack of pupil constriction as the one and only diagnostic factor for concussion. Well I’m here to tell you that they need to be looking at a great deal more than that! Some basic tests to look for when you or a loved one is being examined for suspected concussion are as follows:
1) Observation for eye malpostion
2) Direct and indirect pupil response to light (as noted above)
3) Cardinal fields of gaze (eye movements in all directions)
4) Eye convergence (crossing of the eyes – as your mother told you to never do!)
5) Ophthalmoscopic examination (looking inside the eyes)
6) Visual acuity/Snellen chart (how well you see)
7) Eye cover/uncover testing (more sensitive test for eye deviation)
8) Eye dominance and/or suppression testing
While not an exhaustive list, these tests can be done in a very short period of time (5 minutes or less) with very little equipment and can reveal a great deal about the integrity of these cranial nerves, as well as the higher brain centers that regulate these functions.
That said, there are a host of other very sensitive tests that can offer clinicians incredibly valuable insight into the workings of the ocular (eye) system and its connections with most parts of the brain.
1) Vestibulo-ocular reflex (VOR) testing – often performed with the patient focusing on an object while the examiner moves the head, or while the patient is rotated in a chair
2) Testing for eye saccades (fast movements between targets) – movements are typically over or under compensated with concussion
3) Cortical blind spot mapping – mapping of the visual defect created by the optic nerve attaching into your retina where there are no receptors for light (rods/cones)
4) Testing for optokinetic nystagmus (OKN) – reflexive eye movement caused by tracking of movement within a visual field (i.e. similar to looking out a car’s side window while moving)
5) Electronystagmography (ENG)– advanced electrical testing of various ocular capabilities
Once again, this is by no means an exhaustive list of assessment tools available to the practitioner for evaluation of the eyes and associated brain systems after a head injury, and evaluation options will vary depending on the type of practitioner utilized for assessment (e.g. DC, DO, MD, PT, PhD, etc).
In my humble opinion, given their astute focus on ‘functional’ abnormalities of the nervous system, functional neurologists such as Chiropractic Neurologists and Neuropsychologists are best equipped to deal with these types of conditions; meaning those injuries where there is no observable ‘structural’ damage to the brain. It is no secret that our modern health care system fails to acknowledge and treat these ‘functional’ brain injuries effectively and the long term ramifications of this ‘sit-and-wait’ behavior can be absolutely devastating.
In closing, while I agree there is a greater awareness of brain injury given the publicity provided to it primarily from the great men and women that have been injured serving our country in the past decade or so; I still feel the attention and treatment given to those with ‘milder’ brain injuries like concussion is poor at best within our current system. And this opinion is validated and reinforced daily in my clinic when I see the changes in folks and their families that have been advised to ‘sit-and-wait’. While many sports programs at all levels are implementing strategies such as sideline visual tests like the King-Devick test that are remarkable for evaluating concussion within minutes of the injury, the passive after-care approaches have not changed a whole lot. I am here, along with my colleagues, to ensure that those suffering concussions do not ‘sit-and-wait’, and that they get the evaluation and intervention necessary to return them to their pre-injury (or better) status. Please help us in this mission and pass this on to everyone you know as no one is immune to the possibility of head injury!
~Please check back soon for a follow-up article focused on potential treatment interventions for concussion and TBI~