What does a grand-father say about his grand-son playing football? The opinion tide is shifting as both parents and grand parents assess the risks of concussions. Concussions are perceived as a mild injury that repairs with time. What if the brain repair re-calibrates the brain into a different setting, what we call in the research, a new baseline? Another concussion another new baseline established. What if as our cousin Gabriel listening to his uncle’s concussion understanding fits into his language, Gabby says it so succinctly,.”… if in the very long-term effects of multiple concussions are the early appearance of Alzheimer’s disease, is Alzheimer’s a continuous concussion?” I think that is the statement word choice that needs to be asked to better answer, ‘What are the risks for my grand-son playing football?’ Super Bowl quarterback, Kurt Warner now a broadcaster, has said,…”no question in my mind” that his sons are not playing football. I am referring to a syndicated article written by Tom Rock / NEWSDAY published under the title:FOCUS ON: FOOTBALL- NFL Hall of Famer Carson says he won’t allow grandson to play because there are too many serious injuries in to-days MontrealGazette.com, Tuesday May 8, 2012.
Obviously this debate will be rancorous as one side digs in, pitted against another strong conviction, toward the kind of reply also from a former NFL player, Al Toon whose career was cut short with a severe concussion while playing with New York Jets whose son was drafted by the New Orleans Saints in the fourth round on April 28 this year. Although Toon has concerns for his son’s well-being which is what any parent feels most of the time in my opinion, “We raised our children to make their own decisions.”
But lets take the example of the biology of a concussion. This may help evaluate the risks. What happens in the context of post concussion that short term memory is affected? If you listen to children or adolescents they have trouble concentrating after a concussion. It’s all very well to be concerned about making a proper assessment of a return-to-play for getting back into say a football season, but what about return-to schooling, how is that decision made?
Here is where my thinking is. When you can’t find research reports on testing after concussions in the medical literature if you have read previous essays I have quoted at length, Nigel Shaw’s treatise on The Neurophysiology of Concussions from the University of Auckland, New Zealand. Shaw is surrounded by another kind of football player mentality in New Zealand, rugby football. Same grandfather concerns I would imagine though, for little rugby players on the pitch banging heads together. Shaw states that concussions are singular seizure like episodes of brain deregulation. So if you want to investigate early concussion symptoms affecting learning capacity you can look at pediatric epilepsy toward early learning deficits as if multiple concussions have occurred in a young brain. I am sourcing Epilepsia, 52(2): 377-385, 2011 entitled: Deficits in occulomotor performance in pediatric epilepsy by Miya R. Asato, Natalie Nawrawong, Bruce Hermann, Patricia Crumrine, and Beatrice Lune. The authors probed, …”The integrity of components of cognition-including speed of processing, response inhibition, and spatial working memory-supporting executive function in epilepsy patients compared to matched controls.” Using a total of 44 pairs of controls and medically treated pediatric epilepsy patients with no known brain pathologies completed cognitive occulomotor tasks, computerized neuropsychological testing, and psychiatric assessment.” The authors key findings were in their terms, ‘Patients showed slower reaction time to initiate a saccade response compared to controls but had intact saccade accuracy. Cognitively driven responses including response inhibition were impaired in the patient group. Patients had incidence of psychopathology, but co-morbidity did not predict worse functioning compared to patients with no Attention Deficit Hyperactivity Disorder (ADHD). Epilepsy type and medication were not predictive of outcome. More complex neuropsychological performance was impaired in tasks requiring visual memory and sequential processing, which was correlated with inhibitory control and antisaccade accuracy.” The authors next stated the significance of their observations, “Pediatric epilepsy may be associated with vulnerabilities that specifically undermine speed of processing and response inhibition but not working memory, and may underlie known neuropsychological performance limitations. This particular profile of abnormalities may be associated with seizure-mediated compromises in brain maturation early in development.”
Well there it is, couched in the words of academic lingo. Let me translate a bit hopefully for a clearer understanding. What are saccades? These are the eye movements that are controlled by the delicate contraction of the eye muscles, pivoting the eye as it tracks something, processing the visual field into the brain’s perception. Notice the authors are concluding the development as the brain maturation process is compromised. Notice also that the significance is that the memory system is intact it’s that the eye movements are not properly coordinated into working memory. I find this fact amazing, don’t you? What is going on here? These researchers are saying the memory intake is functioning but the actual eye motion, what they measure the eye saccades with accurate infrared detector to recognize and position the eyes in a motion detecting device. Again I’ll drive home an important observation, the eyes aren’t scanning properly something has affected the eye muscles, affecting the learning capacity. Remember my latest essay on the occulomotor nerve the 3rd cranial nerve? If you go back to the previous essay it’s the yellow line, which is the nerve portion of the occulomotor under the brain before it goes through a little opening, termed a foramen. ‘The somatomotor component of the nerve divides into a superior and inferior division. The superior division supplies the levator palpebrae superioris and superior rectus muscles. The inferior division supplies the medial rectus, inferior rectus and inferior oblique muscles. The visceromotor or parasympathetic component of the oculomotor nerve travels with inferior division. In the orbit the inferior division sends branches that enter the ciliary ganglion where they form functional contacts (synapses) with the ganglion cells. The ganglion cells send nerve fibers into the back of the eye where they travel to ultimately innervate the ciliary muscle and the constrictor pupillae muscle.’
Now there are also other nerves involved with eye motion, the cranial nerves 4 and 6 but I’m not going to elaborate on those nerves at this time. Let’s look at the yellow line, cranial nerve 3, by the way there are two of them for each pair of eye muscle. What happens if you place your grocery bag on the back seat of your car and you have an accident slamming into something. The bag continues moving forward, until it contacts something like the seat or the door depending on the direction of the collision contact. Here’s the question I asked my unofficial adviser, Dr Sandra Miller yesterday. She teaches anatomy to our medical students. “Dr Miller is it possible the eyes move out a little during a concussive blow to the head?” I asked her. “That’s logical,” she surmised, “there’s nothing like being inside the concussed brain for hitting up inside the cranium to stop their progression so they could bulge out during the brief deceleration.” Just like my grocery bags flying off the seat. But if my grocery bags were attached with a bungee cord to the seat belt bracket, the bags would now be tethered and the bungee would stretch in the motion of the collision, no? So what about the occulomotor nerve, that yellow tether running under the brain does it stretch too, and what would happen if it does stretch during a concussion? Your eye muscles contraction capacity would be affected, logically speaking. The eyes appear to move out during a concussion, why wouldn’t they? If the eyes move enough, depending on the imparting force and direction, they tether forces into brain areas that don’t like to be stretched, now things get interesting. This observation is pretty fresh but it starts to get at what actually changes I imagine after a concussion because so far when magnetic resonance (MRI) imaging shows everything looks normal following a concussion, but MRI doesn’t reveal if something has stretched to return to its original position.
Clinical testing involves using visual eye movement tasks, ..” engage complex systems that may overshadow impairments of discrete cognitive components such as response inhibition. ” According to the authors occulomotor testing, …”offers the advantage of using putative tasks of inhibition and working memory, which have been well characterized at the single -cell neuron level in primates.” What exactly are inhibition tasks and how are they tested?
“The anti-saccade response inhibition task assessed inhibitory ability. Participants fixated on a central stimulus for a varied time (500, 2,000, 4,000, or 6,000 milliseconds.) When fixation was extinguished, a peripheral target appeared in an unpredictable location. Participants were instructed not to look at the target but instead to make an eye movement to the mirror location.” The inhibition task is compared to the basic attention and sensorimotor function test. Both visually guided saccade and antisaccade response inhibition use the same target methodology. Each eye task uses varied time stimulus focusing on a fixed point then participants were instructed, ..” to make a saccade as quickly as possible to the random target, presented along the horizontal meridian (left or right of center) at 4 degrees or 8 degrees for 1 second”, compared with the mirror location target. Target locations and timing were unpredictable. “Latency ( time to initiate saccade) and the accuracy of how closely they approximated the target location in degrees of visual angle was recorded for 48 trials.” All the participants were tested in a darkened room at a specific distance from a computer screen. Their head motion was minimized by resting their chin on a rest and their head was restraint strapped to the rest too. Eye tracking was obtained by using a table-mounted near-infrared tracker sampling at 60 Hz utilizing computer software. “The percentage of trials in which the participant looked toward the peripheral targets (response inhibition errors) as well as latency of saccades toward correct and incorrect locations,” were measured. These eye movements were measured by a skilled technician employing specialized software offline.”Results of algorithm-based measurements were presented for graphically and numerically for inspection for each saccade of each trial.”
The memory guided saccade task assessed simple spatial working memory. “Participants fixated on a central stimulus after which an unpredictable target was presented. The participants were instructed to continue to maintain central fixation while remembering the target location after either a short or long delay (4,500 or 7,500 ms) in the absence of a central stimulus. ” The authors measured the latency of correct saccades with the accuracy of the initial saccades to the remembered location as degrees of visual angle. ” Latencies shorter than 67 ms were excluded to remove any guessed, predictive responses as well as any eye blink artifacts noticed by the technician.The authors divided the participants into cohorts of three age groups, (8-10) children, young adolescents (11-14), and older adolescents (15-17) compared to controls within these same age group ranges.
The results showed differences that were significantly longer latencies than controls to,” initiate a saccade assessing basic sensorimotor function testing the visually guided saccades. The patient group made more inhibitory errors compared to the matched controls in the response inhibition antisaccade task. Antisaccade accuracy, estimating the mirror location of the displaced target, was also impaired in the patients. Neither drugs for anti-epilepsy therapy nor epilepsy subtype had no effect on either error rate or accuracy.”
The authors summarize their findings as, ” Epilepsy is associated with impairment in sensorimotor function and response inhibition with sparing of spatial working memory. Developmental impact was suggested by a lack of improvement in response to latency for visually guided saccades and limitations in inhibitory control at younger ages.” The authors imply that executive brain dysfunction which underlies the more complex neuropsychological functioning is a response to the impaired response inhibition latencies observed. Animal models have also revealed, …” the brain circuitry underlying performance in the antisaccade and memory-guided saccade tasks.” ” Given findings in developmental literature of white matter supporting psycho-motor speed, the consistent finding of slower reaction times in patients across oculomotor tasks may relate to epilepsy-mediated effects on white matter. There is emerging evidence of disrupted white matter circuitry occurring in the context of early onset epilepsy in both pediatric and adult populations.”
I think this next statement by the authors carries the most weight. ” Primary to antisaccade performance is the ability to prepare an inhibitory response across cortical and sub-cortical regions. This suggests accordingly, “…that top-down modulation of behavior may be undermined in epilepsy and that surprisingly spatial working memory abilities did not show group differences.” What is going on here? The memory abilities seem to be OK yet the inhibition preparation saccade performance is perturbed. When we think of memory problems in children I don’t think we are dealing with eye muscle movement timing issues within their young occulomotor system. In other words, integrity of the eye moving is linked to the memory formation somehow.
If the occulomotor nerve may be tether stretched during a concussive deceleration blow to the head as the eyes rush slightly out of their sockets, don’t forget movement may be in minute amounts here, probably in angstroms displacement. The image of a cartoon face with bugged out eyes certainly comes to my mind’s eye, but this may be the reality for concussions causing eye movement nerve stretch. Now when that grandson looks at you with those big eyes does the gridiron question have more importance how you will answer him?