It’s a common complaint in my chair. “Doc, it’s the strangest thing. Ever since my brain injury, I haven’t been able to go to a grocery store or a restaurant. Within a few minutes I feel overwhelmed, anxious, dizzy and nauseous. It was never a problem for me before, but now, just the thought of going to a visually crowded area gives me symptoms. Even social situations with 5+ people can trigger symptoms – what is going on?”
Welcome to post-traumatic vestibular-oculomotor dysfunction. What’s going on is your healing brain is realizing just how difficult and complex seemingly easy tasks like going to a grocery store or socializing actually is for the brain. So, lets break it down.
Just like many other autonomic functions in the brain, the vestibular system (inner ear) and the visual system constantly coordinate with each other to tell the brain what is going on in the environment. One of the fastest reflexes in the body, the vestibular-ocular reflex (VOR) works to stabilize the eyes while the head and body are in motion so that while you move around the environment, the visual world appears stable.
Look at the target below – and slowly shake your head side to side while looking at the “X”
While your head moves to the right, your inner ear senses the head movement and tells the eyes to stabilize/move to the left at the same speed but opposite direction of the head in order to maintain visual stability on that target – this is the VOR in action. If there is a disconnect between the eyes and ears, then head and eye movement can make patients dizzy and nauseous. Other eye movements like saccades (ability to move the eyes quickly from one target to another) or smooth pursuits (ability to smoothly track a moving object with the eyes) also depend on the interaction between the ears, eyes, and postural neck muscles (vestibular-spinal and cervical-oculomotor reflex). After a brain injury, the neuronal connections may be misfiring, causing inaccuracy of eye movements leading to physical symptoms like dizziness, nausea, headache, and brain fog.
So, what’s with the anxiety? In simplified terms, the theory behind this particular symptom links to the brain’s utility of the VOR evolutionarily for the fight or flight or sympathetic response. Normally, when the VOR is well functioning, a person is able to centrally focus on a task and ignore but monitor their peripheral vision. If something were to jump out in the periphery, the brain would acknowledge it and respond by moving the head and/or eyes quickly using the VOR or saccades to look at the target to decide how to react – fight? Or flight? If, however, the VOR and or saccades are malfunctioning either because of a central or peripheral dysfunction of the vestibular-oculomotor system, the brain is less likely to ignore its peripheral vision – so instead it focuses on everything in your visual scene both centrally and peripherally, ALL of the time. If we focus on everything, then we are unable to fixate on one single thing. So when you go to a very visually crowded area, the brain gets overwhelmed, and for many patients a sense of panic sets in.
So back to the grocery store – why is it so awful?
Well first of all, grocery shopping is a VERY complicated cognitive and visual-vestibular task. Let’s pretend you only want to buy one thing – lets say… ketchup. You walk into the store and the fluorescent overhead lighting starts to overstimulate the visual-vestibular system right away due to its inherently high flicker frequency – so the headache starts to creep in. As you walk in you have to balance and coordinate your head/eye/body movements, as well as remember what exactly you are looking for. Oh right… ketchup! Then you must find the aisle it is in so you need your associative memory/cognitive skills – “ketchup is a condiment, that would be located near other condiments, where is that?!”
You visually search for the sign above the aisle for condiments using your saccadic eye movements, which post-brain injury now make you dizzy. You steady yourself on your cart and slowly walk down the aisle, trying to ignore the auditory stimuli (people talking, children screaming, music blaring), and finally you get to the… wait, what were you looking for again? Oh right… ketchup! But which ketchup do you want? Large or small? Brand or off-brand? Sugar free or sugar full?… what were you looking for again? Oh right… ketchup!
You move your eyes and head back and forth scanning the ketchup options and the mismatched VOR triggers further dizziness, nausea, headache, brain fog, and then you start to just get overwhelmed, hot, and anxious – when are you going to get out of here? You take a deep breath, calm yourself down – I mean it’s just the grocery store! You reassure yourself – you can do this! Wait, what were you looking for again? Oh right… ketchup!
You finally pick out your ketchup and visually locate the one you want and then you need to coordinate your hand to reach out and grab the one you want – which means your visual system needs to fixate on one and ignore the surrounding hundreds. You also need to coordinate your hand to the bottle which usually requires saccadic and smooth pursuit eye motion as you place the item into your basket. Success! Now how do you get out of here?
Vestibular-oculomotor dysfunction can significantly impact seemingly simple tasks of daily living, and when left untreated can cause social isolation at home, sadness, and depression as we stop doing the things that we enjoy. The good news? Vestibular-oculomotor dysfunction is treatable, and you can do the rehab from home!
If you need help following a concussion or more severe traumatic brain injury, please consider reaching out to us at 804-270-5484. We are more than happy to assist in any way we can to facilitate you getting the best health care for your problems as soon as possible.