Concussion update

Concussion update

Albert Ski Cross training, high performance sport sees many concussions

When my boys were in the age 11-12 ski racing program, I became acutely aware of concussion and the problems it can cause. I was a brain imaging person so it was easy for me to delve into the literature to see what was known. There 6605 papers in pubmed today with the keyword concussion. If you studied 2 papers a day, it would take you 9 years to read this. Yet we don’t know what the link is between symptoms and injury in the brain, and we don’t know how best to detect the injury. Right now, the diagnosis is largely based on questions to the patient. Increasingly, things like reaction times, indices of balance, motor skills are being measured.

So, I asked two exceptional people to help with a public forum on concussion. We ran this forum 3 times at Canada Olympic park, over the past 4 years.

Dr. Karen Barlow is an Associate Professor of Pediatric Neurology at the Alberta Children’s Hospital Research Institute for Child and Maternal Health. She is a specialist in concussion and traumatic brain injury. Dr. Kelly Brett is a sports medicine physician at the University of Calgary Sports Medicine clinic and is the Head physician for the Calgary Flames hockey team.

There has been A LOT of interest in concussion. I think there are 3 main questions: What is concussion, how do you prevent it, and how do you cure it?

Concussion is currently defined by the symptoms. There are forms that you can use such as the standard concussion assessment tool (SCAT2 or 3) etC.

Guskiewicz KM, Register-Mihalik J, McCrory P, McCrea M, Johnston K, Makdissi M, Dvorak J, Davis G, and Meeuwisse W. 2013. Evidence-based approach to revising the SCAT2: introducing the SCAT3. Br J Sports Med 47: 289-293.

 The biological link, or the precise damage that occurs in the brain that causes these symptoms, just isn’t known.

One can make an educated guess.  “Ringing your bell” could break the fine connections that transfer information in the brain. These connections, (the synapses) as well as the wires (the axons), are very fragile. The barrier between the blood and the tissue of the brain, the “blood-brain barrier” is also fragile. The barrier is partly physical, in that there are collections of cells that form a wall between the blood and the brain. The barrier is also “regulatory”, in that transport processes in these barrier cells determine what crosses into the brain or returns to the blood. There can be disruption to either, or both, of the physical and regulatory components of the BBB. Such disruption can cause chemicals to cross into the brain that can damage cells and can cause the brain to swell. There may be metabolic disruption. The energy factory in the cell, the mitochondria, may be damaged in some way.

Headache, nausea, and not feeling quite right are just some of the symptoms. Even “not feeling quite right” should be taken seriously. Keep in mind the headache only comes from the surface of the brain. There are no pain sensors in the brain. Only from surface layer, largely in the membrane called the meninges, do you receive pain signals. So—you can easily see that damage can occur in the brain with no associated pain (or headache).

It’s easy to say you can prevent concussion by removing head hits from sport, but in reality head hits are not the only problem. Your head can get shaken up badly with a hit to the chest or a fall. The head has to move violently to have the brain shaken up. A sharp rap to the head may not cause a concussion due to the resistance in your fluid filled brain box (the skull) that prevents a very sharp knock from moving the brain. Hits or falls which cause large movements of the whole head are usually more serious.

So, we don’t know what it is and we can’t prevent them. We can reduce them through training and good helmets but a good helmet won’t eliminate concussions either—sorry. Even with a helmet you can shake your brain. We are left with making sure we recognize concussion and that one works hard to minimize the long term damage.

What can be said is that the first hours may be associated with more life threatening problems like bleeding on the brain. It is very important that the subject be properly evaluated. Depending on the symptoms, you may or may not have CT or MRI to look for complications. These imaging methods are used to rule out more severe problems. There is no imaging method currently available that can be used to diagnose concussion itself. MRI holds promise. I’m an MRI researcher so I’m hoping for a home run here.

I’m also a researcher into studying brain activity with optical (light) imaging. We just published a paper detecting changes in brain communication using fNIRS.

Urban KJ, Barlow K, Goodyear BG, Jimenez JJ, and Dunn JF. Functional Near-Infrared Spectroscopy Reveals Reduced Inter-hemispheric Cortical Communication Following Pediatric Concussion. 2014 J Neurotrauma.epub

It is critical to keep the person quiet. The first 3 days, the person is symptom free, then you can consider doing some exercise.

Brown NJ, Mannix RC, O'Brien MJ, Gostine D, Collins MW, and Meehan WP, 3rd. 2014. Effect of cognitive activity level on duration of post-concussion symptoms. Pediatrics 133: e299-304.

In the old days, two weeks off was considered enough. Now it is understood that each person is an individual and each concussion is unique. There are no generalizations on how long it will take to return to play. Watch symptoms. Do some exercise to elevate the heart rate (say to 120). if there are no symptoms, then over the next days gradually increase the exercise. If symptoms occur, back off to the point where there were no symptoms and starts again. If you have had a bad concussion, having medical advice during this phase would be important.

There are advantages to taking concussion seriously. If you “aren’t feeling quite right” and try to throw yourself down a super-G course at 110kph, the results may not be pretty. In other words, your coordination may not be perfect and so you have an increased risk of falling and getting another concussion. A second more obvious reason is that if the damage isn’t healed, you may make it worse.

Dr. Barlow noted that most kids get better pretty rapidly, and have no long term symptoms. Dr. Brett noted that if the symptoms aren’t getting better, make sure you have your neck examined. Upper neck injuries can cause the same symptoms as concussion.

Barlow KM, Crawford S, Stevenson A, Sandhu SS, Belanger F, and Dewey D. 2010. Epidemiology of postconcussion syndrome in pediatric mild traumatic brain injury. Pediatrics 126: e374-381.

There is great information on the Ontario neurotrauma website

http://onf.org/documents/guidelines-for-pediatric-concussion

One of my goals as a medical researcher is to improve the diagnosis and monitoring of concussion patients. I hope that someday soon, there will be more specific answers to some of the three main questions.