April 11, 2011, Kitchener, Ontario
Posted by: Robert Deutschmann, Personal Injury Lawyer
The Toronto Star provides an excellent story on the impact of concussions and injury to the brain. One should not be lulled into thinking trauma to the head is insignificant. It is difficult to assess the true impact of damage to the brain in the skull.
Why a blow to the head is a big deal
April 8, 2011Megan Ogilvie
Ben Dalpe remembers nothing of the hit that slammed his head against the boards and left him face down, unconscious, on the ice.
His parents didn’t see the 16-year-old crumple. They just took in the awful stillness of his body and the silence that fell on the arena after the referee’s whistle halted the game.
As she waited for her son to move, a deep, maternal feeling told Lisa Dalpe that something was terribly wrong.
She was right. The dangerous process we call a concussion was unfolding inside his skull.
Scientists are working hard to piece together what happens to the brain when it is rocked by a concussion. The emerging picture, formed in large part by research conducted in Toronto, is complex, fascinating and a little bit scary.
High-profile hockey players have recently pushed concussions to the top of news headlines and sportscast chatter. But in many ways, popular culture has yet to catch up with what researchers are discovering about concussion, still failing to recognize that it’s a traumatic brain injury.
For some people, a single concussion can cause lasting damage, especially if the patient doesn’t spend enough time recovering. For others, repeated concussions can lead to cognitive impairment, depression and, in rare cases, suicide.
On March 3 in Brantford, Dalpe had been skating along the boards, waiting to receive the puck. It was the second game of a semi-final series, which pitted his Brantford Golden Eagles against the Kitchener Dutchmen, and he knew each play would count.
As the puck touched his stick, an opposing player checked Dalpe from behind. The hit caught Dalpe at the base of his helmet and propelled the left side of his head into the boards.
When it struck — hard enough to make the long stretch of glass undulate — Dalpe’s skull came to an abrupt halt. His brain, however, kept travelling an instant longer, moving through the intracranial space before smacking against the inside bone of his skull. Energy from that collision rippled through his brain tissue, triggering a mini-seizure, shearing nerve fibres and setting off a dangerous biochemical cascade.
After a few minutes face down on the ice, Dalpe opened his eyes and tried to get up.
He didn’t know he had been hit. He just knew his legs felt like rubber and would not hold his weight.
With some help, Dalpe was able to get to the dressing room, where he eased himself into a chair. That’s when he realized he was injured.
“My whole head hurt,” he now recalls. “It was pounding really bad. I didn’t know what to think. But it was definitely the worst headache I’ve ever had in my life.”
Each year, more than 30,000 Canadians are told they have a concussion. Thousands more likely go undiagnosed.
Despite being part of medical knowledge for thousands of years, concussion continues to be both an injury that elicits a ho-hum response (as in “he’s fine; it’s just a concussion”) and a leading cause of disability in young people.
That discrepancy persists largely because a concussion is nearly impossible to see on modern imaging equipment. It has been difficult to both diagnose and research. And its symptoms are so variable, individual and unpredictable that a clear picture started to emerge only in the past 10 years.
Societal reasons, too, have been an obstacle to recognizing the seriousness of the injury. When concussions became associated with sports, rather than with general head trauma, they were lumped in with minor athletic injuries, the equivalent of, say, strained hamstrings. Athletes were encouraged to ignore ringing ears and to play through nauseating dizziness. Those who reported symptoms were often told it was all in their heads
Hockey headlines and the experience of sports superstars — most recently hockey player Sidney Crosby —have drawn attention to the potentially disabling effects of a concussion. But some experts worry it’s not happening quickly enough.
“Everybody used to smoke, then we found out how bad it could be for you,” says Paul Comper, a neuropsychologist at the Toronto Rehabilitation Institute and consultant to the National Hockey League Players Association. “It may come to the same thing with concussion.”
One of the enduring misconceptions about concussion is that it is a bruise to the brain.
A hit to the head does shake the brain inside the skull. But it is the absence of any visible structural damage to the brain, combined with symptoms of headache, nausea and fatigue, that leads to a diagnosis of concussion.
“If you could actually point to a picture of the brain and say these cells are bruised, this bled here, that is called a brain contusion, not a concussion,” says Dr. Doug Richards, medical director of the David L. MacIntosh Sport Medicine Clinic at the University of Toronto.
Another thing experts point out is that the brain is the consistency of not-quite-jelled Jell-O. Or very thick mayonnaise.
It consists of excitable tissue with mini electrical charges constantly travelling across cell walls to activate neurons.
When the brain gets hit hard, all of the cells discharge electricity at once, triggering a traumatic seizure.
““The brain goes brrrrrrrrp and is temporarily out of order,” says Richards.
This massive electrical discharge is why people who have suffered a concussion are initially dazed and confused. The hit has obliterated their short-term memory.
“They can’t remember their name, where they are, what day it is, what they are doing,” says Richards. “It’s kind of like the brain has to reboot because the seizure has wiped the slate clean.”
For some people, the reboot — the return of normal electrical currents across cell membranes — can take minutes. Others experience just a momentary loss of awareness.
Up until the early years of this century, it was thought a diagnosis of concussion could be made only if a person had been knocked unconscious. Researchers now know that the key indicator is an alteration of awareness, whether for seconds or minutes.
A trauma-induced seizure sounds scary, and is likely so for the people who experience a concussion. But scientists suspect the degree to which the brain twists inside the skull has a greater impact on the severity of a concussion.
To understand this process, you first have to learn a little about brain anatomy.
The brain is roughly composed of two things: grey matter and white matter. Grey matter, made up primarily of neurons, is distributed both on the surface of the brain and deep inside the organ. White matter consists mainly of axons — covered in a protective coating of myelin — which carry nerve impulses between neurons.
Now, imagine holding someone’s head in your hands, much like a beach ball, and swinging it hard to the right. The heavier, denser grey matter will move faster than the lighter white matter. Axons within the white matter get stretched or sheared — some will even snap — damaging the protective myelin coating. Tears in the myelin slow or disrupt communication between cells.
The amount of axon damage is related to the force of a hit and — more significantly, scientists surmise — the direction of the hit to the head. One that catches a person on the side of the head, twisting it sharply to the side, creates greater shearing force than a hit that rocks the skull from front to back.
Richards says studies have shown people with severe brain injury, the kind that puts people in comas, have large swaths of damaged axons. Only recently has axonal damage been linked to concussions.
“When I was in medical school, I was taught that no such damage existed in mild brain injuries,” he recalls. At the time, imaging tools used to view the brain were not able to detect small amounts of axon damage.
In the past few years, more sophisticated tools and techniques have allowed scientists a glimpse at the tiny tears in brain tissue rendered by concussions.
One of these tools is diffusion tensor imaging, or DTI, which uses advanced software to get more information from an MRI image. DTI detects how water molecules move along the myelinated axons in white matter. In a healthy person, water should track closely to axons.
“But when you damage the white matter, you allow for freer movement of water molecules,” says Robin Green, director of Toronto Rehab’s Cognitive Neurorehabilitation Sciences Lab. “That’s what DTI picks up.”
In a very basic sense, mapping abnormal water movement in the brain is like finding where water seeps out of a leaky pipe.
In separate experiments, Green and Richards are investigating whether DTI will lead to a better way to diagnose concussions. Both admit it could take years before DTI makes its way to the clinic.
When David Hovda was first asked to present his research to the National Football League in the 1990s, the commissioner told him concussions did not occur in the NFL.
“The player association said the same thing and the physicians associated with the teams said the same thing,” recalls Hovda, director of the UCLA Brain Injury Research Center.
Throughout that decade, using tests devised by the World Boxing Federation, Hovda helped the league recognize that many of its players had indeed been concussed.
“There were a lot of people for many years that thought a concussion was a psychological phenomenon, not a neuroscientific phenomenon,” Hovda says. “It had to do with your emotions or your psychology of how you responded to pain.
“(The thinking was) if you could play through the pain of an injured shoulder, you should play through the pain of getting your bell rung.”
Back in his labs at UCLA, Hovda and his colleagues were investigating the neurochemistry of concussion. What they found — and are continuing to reveal — is fascinating.
When the brain rattles from a hit to the head, cell membranes open up and a biochemical cascade washes through the tissue and disturbs its precise chemical balance. Specifically, potassium floods out of the cells, while calcium rushes in.
The cells desperately want to restore balance, which requires a huge amount of energy. For a healthy person, this is an easy thing do. But a concussion mucks up a host of other chemical processes that affect how the brain produces energy.
The first problem is that calcium, in high levels, is toxic to brain cells. Normally, the brain would lower calcium levels by drawing on the power of mitochondria— the energy factories found inside all cells. But as the mitochondria work to reduce super-high calcium levels, they clog and don’t produce enough energy.
At the same time, the brain is still seeking energy to restore its chemical balance, so it sends out an emergency signal for more glucose. Usually, glucose — the brain’s primary fuel — is carried to needy areas by an increased flow of blood.
But a concussion affects this process, too. After a hit, blood vessels constrict, making it difficult for blood to carry glucose to where it is needed most.
Now — just minutes after a concussion — the brain is in an all-out crisis. It can take days, weeks or even longer for the brain to get back its normal chemical balance.
People who have a concussion will describe being overwhelmingly tired. This weariness is actually a neural fatigue, brought on when the brain doesn’t get enough fuel and must struggle to perform. Pushing through the fatigue is one of the worst things somebody with concussion can do.
“During this energy crisis, the brain wants to shut down and be very, very quiet,” says Hovda. “If you exercise the brain, or if you experience another brain injury (during this time), you will prolong the symptoms associated with concussion and extend the period of vulnerability.”
Scientists believe that injuring the brain or forcing it to work hard, whether from sports of homework, during this window can kill brain cells, creating a more devastating injury.
The most recent research in animals suggests the brain is most vulnerable to reinjury days after a concussion, not the day of, which has major implications for when a person or athlete can return to work or play.
Two years ago, Hovda’s research helped to create a Washington state law that requires young athletes suspected of getting a concussion to undergo a medical inspection and clearance before they can return to play, whether a practice or a game. The law is named after Zackery Lystedt, a middle-school student who suffered a serious brain injury after being sent back into a football game following a concussion, and who remains disabled five years later. Fourteen states have since adopted the law.
Beyond the scientific contribution, Hovda’s work has helped make people appreciate the gravity of concussions. He now travels the world, lecturing two or three times a month, and his audiences have included the NFL, the NHL, numerous other athletic organizations, medical researchers and doctors, and the U.S. Department of Defense.
When Hovda came to Hamilton a few years ago, Walter Gretzky tried to give him Wayne’s old leather helmet as a thank you for illuminating the neurobiology of concussion.
“I thanked him back,” Hovda laughs. “But I said the helmet should stay in Canada.”
In the days after his concussion, Dalpe stayed in his bedroom, the shades drawn against the light.
A concussion expert had told him to rest. That meant absolutely no exercise, and no homework. And definitely no video games.
For the first week, Dalpe’s head hurt so much he didn’t stray far from his bedroom — except to celebrate his 17th birthday. By the second week, Dalpe felt better and found it hard to keep still. He ended up cleaning his long-neglected room.
Currently, the only treatment for concussion is physical and cognitive rest. Doctors rely on standard neuropsychology tests to help determine the severity of an injury and whether a concussed brain has healed.
Scientists’ long-term hope is that uncovering the biology of concussion will point to new ways to treat the injury. And provide more insight on when symptoms will fade.
“That’s the $65 million question,” says Hovda. “How long does somebody stay out? The best thing we have come up with is: as long as they have symptoms they stay out.”
In the first 24 hours after his concussion, Dalpe was given two widely different prognoses. One emergency room doctor told him he could be back playing hockey in seven to 10 days. Another told him he would never play hockey again, a devastating statement that wiped away Dalpe’s dream of joining the NHL like his older brother Zac.
He and his parents sought out a concussion clinic in Hamilton, whose experts said Dalpe could play hockey again as long as he let his brain fully heal.
While the majority of those who suffer a concussion will get better in one to three weeks, about 15 to 20 per cent of patients will have symptoms that linger for months and sometimes years. Scientists suspect these patients may have a genetic predisposition that makes their brain more vulnerable to concussion.
Researchers are also trying to figure out why only some people are affected by an accumulation of concussions by teasing out the link between repetitive injuries and chronic traumatic encephalopathy, a progressive degenerative disease that seems to mirror the biology and symptoms of Alzheimer’s. Connections have also been made between accumulated head trauma and devastating diseases such as Lou Gehrig’s and Parkinson’s.
Concussions can also trigger psychological issues in some people, including anxiety disorders and depression.
And research has revealed concussions are different in children compared to adults, women compared to men, and young adults compared to the elderly.
The range of severity and permutation of both short-term and long-term symptoms has led Richards of U of T to suggest the diagnosis of a concussion is much too broad.
“It’s like the difference between saying you have low back pain and saying you have a herniated disk or you have a strained muscle or you have a broken bone,” he explains.
Richards predicts a rush of findings will come out of labs in the coming decade — new insights leading to specific treatment plans and prognoses depending on the nature of the blow.
And, hopefully, the new understanding of the injury’s terrible ability to thwart lives will lead to preventive measures, so that athletes like Dalpe won’t get concussed in the first place.