Sport related concussion is a traumatic brain injury induced by bio mechanical forces. Several common features that may be utilized in clinically defining the nature of a concussive head injury include:

Chronic Traumatic Encephalopathy (CTE) is the term used to describe brain degeneration likely caused by repeated head traumas.  Unfortunately, CTE  is diagnosis made only at autopsy by studying sections of the brain. CTE  has complex relationship to head traumas such as post-concussion syndrome and second impact syndrome that occur earlier in life. Experts are still trying to understand how repeated head traumas - including how many head injuries and the severity of those injuries- and other factors might contribute to the changes in the brain that result in CTE.

From punch drunk syndrome to CTE: In 1928, New Jersey pathologist Harrison Martland observed boxers taking jarring hits in the ring often became "punch drunk" afterward. The fighters took one or two hours to recover, but many of them developed troubling changes over time problems with gait, tremors, and impaired memory years after they stopped fighting. The boxers most likely to suffer appeared to be the ones who spent the greatest number of years in the ring and took the most blows.

Scientists initially attributed punch drunk syndrome to the uniquely violent sport of boxing, referring to it as "traumatic encephalitic of pugilists' or dementia pugilistic'- boxers dementia. As researchers studied boxers, they began to identify hallmarks of the disease that would become known as chronic traumatic encephalopathy. (CTE): loss of neurons in the cortex and an expansion of the brain's ventricles- cavities in the middle of the brain where cerebrospinal fluid is produced. In addition, the boxers' brains possessed tangled deposits of an abnormally-formed protein called tau inside neurons  near blood vessels.  

CTE has been found in the brains of people who played football and other contact sports, including boxing.  Some signs and symptoms of CTE are thought to include difficulties with thinking (cognition) physical problems, emotions and other behaviors. It's thought that these develop years to decades after head trauma occurs.

Some of the possible signs and symptoms of CTE  can occur in many other conditions, but  in the few people with proven CTE, symptoms have included: 1) Difficulty thinking  (cognitive impairment), 2) Impulsive behavior 3) Depression or apathy 4) Short-term memory loss 5) Difficult planning and carrying out tasks (executive function) 6) Emotional instability 7) Substance misuse 8) Suicidal thoughts or behavior Chronic traumatic encephalopathy can occur in young individuals as young as seventeen years old, though symptoms do not appear immediately until years after the occurrence of head collisions. Common concussion symptoms are a loss of memory, head pain, blurred vision and dizziness.

Doctors considered CTE a disease of boxers until 2005 when neuropathologist Bennet Omalu discovered abnormal tau tangles in an autopsy of American football player Mike Webster's brain. The Pittsburgh Steelers' legendary center had post-NFL years filled with devastating cognitive decline, depression, and erratic behavior. Webster sometimes forgot how to eat or how to find his way home. Omalu's investigation into the source of Webster's cognitive issues opened the floodgates for studying CTE in football players and other athletes participating in contact sports.

CTE can only be definitively diagnosed at autopsy - a tremendous hurdle for scientists and physicians hoping to treat and prevent the disease.  However, during his lifetime, Webster experienced a cascade of common symptoms that people found to have died with CTE suffer from: headaches, loss of attention, and concentration. For many, their judgement can become impaired and they may suffer mood swings, depression, memory loss, difficulties with language, Parkinson's like tremors, and an increase in suicidal idealization.

Tau is present in all of our brains. Normally, the various forms of the protein fold into soluble molecules that stabilize microtubules - structures in the neuron that act like a  highway for transporting proteins from one end of the neuron to another. Tau only becomes a problem when it folds inappropriately into tangled filaments inside neurons. These neurofibrillary tangles, also called tau inclusions, arise in a number of neurodegenerative diseases including Alzheimer's disease (AD) and CTE.

"The largest risk factor for CTE that we know of right now is a history of contact sports," says Jonathan Cherry, a neuroscientist at Boston University School of Medicine. "In fact, the more years a person plays sports or the younger they are when they start taking hits seems to speed up the progress of CTE, he says. In one study athletes who began playing football before the age of 12 developed the cognitive and behavior symptoms of CTE , 13 years earlier on average than those who started playing later in their teenage years.

With neurodegenerative diseases like AD  and CTE, neural damage accumulates as tau tangles spread. The problem for scientists and physicians lies in the fact that it's not clear how head injuries result in tau inclusions. "We really don't know what dose of the blows to the head are needed to cause this degenerative cascade, says Daniel Perl, a neuropathologist. 

Developing a Diagnostic: Currently, sports teams track the impact of brain injuries by assessing players' cognitive abilities at baseline and frequently reassessing after concussions. Such efforts may miss an important risk for CTE: subconcussions, hits which shake the brain but not so violently that there are any obvious symptoms. "Just because you don't see an issue, because there's no concussion or immediate unconsciousness, doesn't mean there hasn't been some damage to the brain, " 

The considerable latency between suffering a blow to the head and developing symptoms associated with CTE complicates efforts to understand and address CTE, However, scientist are beginning to get some clues about CTE thanks to technologies that weren't previously available. The combination of positron emission tomography (PET) and tau specific ligands allow researchers to see that there are more tau deposits in the brains of living former NFL players than other men with no history of traumatic brain injury. Whether such accumulation is predictive of developing CTE is an open question.

Because CTE can only be diagnosed after the person has died, treatment can be challenging. Treatment for people who have symptoms of CTE include, behavioral therapy to deal with mood swings. Pain management therapy, including medicines, massage and acupuncture, to relieve discomfort. Memory exercises to strengthen the ability to recall daily events.

There are an estimated 1.7 to 3.8 million traumatic brain injuries each year in the United States, according to the CDC, of which 10 percent arise due to sports and recreational activities. Amongst American children and adolescents, sports and recreational activities contribute to over 21 percent of all traumatic brain injuries. Sustaining an injury while playing sports can range from a mild physical trauma such as a scalp contusion or laceration to severe TBI with concurrent bleeding in the brain or coma. It is important to recognize when a head trauma is severe or has resulted in a TBI because it is crucial to seek immediate medical attention. While most brain injuries are self-limiting with symptoms resolving in a week, a growing amount of research has now established that the sequelae from recurrent minor impacts is significant in the long term.

Traumatic Brain Injury

A traumatic brain injury (TBI) is defined as a form of acquired brain injury from a blow or jolt to the head or a penetrating head injury that disrupts the normal function of the brain. TBI can result when the head suddenly and violently hits an object, or when an object pierces the skull and enters brain tissue. Symptoms of a TBI can be mild, moderate, or severe, depending on the extent of damage to the brain. Mild cases (mild, traumatic brain injury, or mTBI) may result in a brief change in mental state or consciousness, while severe cases may result in extended periods of unconsciousness, coma or even death. Individuals with TBI may experience one or more of the following:

• Pain: Constant or recurring headache
• Motor Dysfunction: Inability to control or coordinate motor functions, or disturbance with balance
• Sensory: Changes in ability to hear, taste or see; dizziness; hypersensitivity to light or sound
• Cognitive: Agitation; confusion; shortened attention span; easily distracted; overstimulated by environment; difficulty following directions or understanding information; feeling of disorientation and confusion and other neuropsychological deficiencies
• Speech: Difficulty finding the "right" word; difficulty expressing words or thoughts; dysarthric or slurred speech

Concussions

Concussions frequently affect athletes in both contact and non-contact sports, and are considered to be diffuse brain injuries that traumatically induce alterations of mental status. A concussion may result from shaking the brain within the skull and, if severe, can cause shearing injuries to nerve fibers and neurons.

The 5th International Conference on Concussion in Sport held in Berlin, Germany, in 2016 defined Sport-related Concussion as:

Sport-related concussion is the historical term representing low velocity injuries that cause brain ‘shaking’ resulting in clinical symptoms and that are not necessarily related to a pathological injury. Concussion is a subset of TBI and will be the term used in this document. It was also noted that the term commotio cerebri is often used in European and other countries. Minor revisions were made to the definition of concussion, which is defined as follows:

Sport related concussion is a traumatic brain injury induced by biomechanical forces. Several common features that may be utilized in clinically defining the nature of a concussive head injury include:

1. Sport related concussion may be caused either by a direct blow to the head, face, neck or elsewhere on the body with an “impulsive” force transmitted to the head.
2. Sport related concussion typically results in the rapid onset of short-lived impairment of neurological function that resolves spontaneously. However, in some cases, signs and symptoms evolve over a number of minutes to hours.
3. Sport related concussion may result in neuropathological changes, but the acute clinical symptoms largely reflect a functional disturbance rather than a structural injury and, as such, no abnormality is seen on standard structural neuroimaging studies.
4. Sport related concussion results in a range of clinical symptoms that may or may not involve loss of consciousness. Resolution of the clinical and cognitive symptoms typically follows a sequential course. However, it is important to note that in some cases symptoms may be prolonged.

The clinical signs and symptoms should not be explained by drug, alcohol, or medication use, other injuries (such as cervical injuries, peripheral vestibular dysfunction, etc.) or other comorbidities (e.g., psychological factors or coexisting medical conditions). 

To view peer-reviewed literature related to sports concussions, the Sports Concussion Library can be found here.

Grading the concussion can be a helpful tool in the management of the injury and depends on:

1. Presence or absence of loss of consciousness;
2. Duration of loss of consciousness;
3. Duration of posttraumatic memory loss; and
4. Persistence of symptoms, including headache, dizziness, lack of concentration, etc.

Some team physicians and trainers evaluate an athlete's mental status by using a five-minute series of questions and physical exercises known as the Standardized Assessment of Concussion (SAC).  More recently, teams have employed ImPACT, a 25-minute computer-based testing program specifically designed for the management of sports-related concussion. A player who has sustained a concussion is three to six times more likely to sustain another one. While the decision when an athlete is ready to return to play isn't straightforward — when in November of 2013 a professional soccer player helped bring his team to victory despite having lost consciousness and dislocating five vertebrae — every player could benefit from baseline neurological testing before the season so that the results can be used for comparison in the event the athlete receives a blow to the head.

TEENS & CONCUSSIONS

Teens may be more vulnerable to the effects of concussions than either adults or younger children, a new study says.

In the study, teens had larger impairments on tests of working memory — the ability to process and store short-term information in the brain, which is needed for learning — six months after they suffered a concussion compared with adults and children.

The region of the brain responsible for working memory, known as the frontal lobe, undergoes a growth spurt during adolescence, making it more fragile and susceptible to the effects of concussions, said study researcher David Ellemberg, a professor of kinesiology at the University of Montréal in Quebec.

Deficits in working memory can impair a person's ability do everyday things, such as multitasking, Ellemberg said.

CTEMEDICAL.COM

When BMX icon Dave Mirra was found dead of an apparent suicide last Thursday, his friends and family, as well as his many fans, were left asking: Why? Theories quickly emerged—namely, that the head injuries he sustained during his BMX career had harmed him more than was previously thought. Soon, publications ranging from the New York Daily News to the Guardian began tentatively linking Mirra’s death with chronic traumatic encephalopathy, the degenerative brain condition better known as CTE.

CTE, which is brought on by repeated severe head impacts, has been associated with impulse control problems, depression, and progressive dementia. Athletes in full-contact sports such as football and hockey are believed to have a much higher risk of developing CTE. Barring a brain autopsy, it’s impossible to know whether Mirra suffered from CTE—but his death, along with an increasing awareness of the condition, has led many cyclists to wonder, and worry: Are they at risk of developing CTE?