By Gina Shaw
November 2, 2023

Over the last two to three decades, much has changed in the diagnosis and management of concussion, particularly in sports but also in head injury caused by other forms of trauma, including falls and car accidents. Now, researchers are on the verge of developing even more advanced technologies for assessing concussion, such as blood-based biomarkers.

When pediatric neurologist Meeryo Choe, MD, FAAN, experienced a concussion as a collegiate swimmer in the mid-1990s, she was taken to the hospital emergency department after she began throwing up.

“The ED physician did a very basic exam, like ‘follow my finger,’ took a history, and told me to avoid all activity for a week,” said Dr. Choe, now an associate professor of pediatrics at David Geffen School of Medicine at UCLA and associate director of the UCLA Steve Tisch BrainSPORT sports neurology/neurotrauma fellowship program.

“At that time, there really wasn’t a protocol that anyone followed for standardized concussion examinations on the athletic sidelines or in the emergency department, and the way most places managed a concussion was to tell you to lie down in a dark room for a week and then you could go back to your normal activities.”

In the 30 years since Dr. Choe’s experience with her own concussion, a great deal has changed regarding its diagnosis and management, particularly in sports but also in head injury caused by other forms of trauma, such as falls and car accidents.

“In that time, we’ve gone from having [to ask] ‘How many fingers am I holding up?’ as the standard of care in concussion assessment to the adoption of well-validated, standardized clinical tools for concussion evaluation and clear protocols for rehabilitation and gradual return to activity,” said Michael McCrea, PhD, an endowed chair in neurosurgery and professor and vice chair of research at Medical College of Wisconsin, where he is co-director of the Neurotrauma Research Center and director of the Brain Injury Research Program.

“And we are on the verge of even more advanced technologies, including blood-based biomarkers for the assessment of concussion. That’s unbelievable progress.”

“Between the mid-1980s and the early 1990s, three concussion grading scales were released, including the Cantu scale, the Colorado guidelines, and the AAN guidelines,” said Brian Hainline, MD, FAAN, clinical professor of neurology at NYU Grossman School of Medicine and chief medical officer of the NCAA.

“This was new, compared with the way concussion had been considered earlier in the 20th century—as a serious brain injury, usually with hemorrhages or contusions of the brain and/or fractures of the skull. For the first time, neurologists and sports physicians were looking at concussion as a mild traumatic brain injury [TBI] that could be managed sometimes on the same day and sometimes over a period of several days,” said Dr. Hainline, who also is an adjunct clinical professor of neurology at Indiana University School of Medicine.

In 2001, the first International Symposium on Concussion in Sport was held in Vienna, Austria, organized by the International Ice Hockey Federation, the Federation Internationale de Football Association Medical Assessment and Research Centre, and the International Olympic Committee Medical Commission. There, participants agreed that a systematic approach to concussion was needed, including a revised definition of what constitutes a concussion. (See “What Is Concussion.”)

Prior to the symposium, the definition of concussion had been based on a consensus publication from the Congress of Neurological Surgeons published in 1966 and later endorsed by the American Medical Association. But experts contended that the publication was limited in its ability to account for common symptoms of concussion and to include relatively minor impact injuries that result in persistent physical and/or cognitive symptoms.

The Vienna conference in 2001 also acknowledged the limitations of the multiple concussion grading scales used to assess injury severity. At the second International Symposium on Concussion in Sport, held in 2004, a panel of experts known as the Concussion in Sport Group (CISG) developed the Sport Concussion Assessment Tool (SCAT), which rapidly became the primary standardized tool for health care professionals evaluating concussion.

The SCAT has been updated several times over the past two decades; the most recent iteration, SCAT6, was published in the British Medical Journal in June. It is intended to be given in the acute phase, ideally within 72 hours, and up to seven days following injury.

“Although designed for sports-related concussion, we typically extrapolate the SCAT to non-sports concussion patients as well,” said Amaal J. Starling, MD, FAAN, associate professor of neurology at the Mayo Clinic in Scottsdale, AZ. “It includes a list of 22 different symptoms, each graded on a scale of 0 to 6 with regard to severity, as well as a supplementary cognitive screening based on the standardized assessment of concussion (SAC), including word lists and repeating digits backward, and a coordination and balance examination using the modified BESS [Balance Error Scoring System] and the Timed Tandem Gait.”

And while “SCAT6 is considered the gold standard,” Dr. Starling added, “we still do not have any single tool that has been proven to be 100 percent sensitive and specific for concussion.”

“Concussion affects networks in the brain, so one tool alone can’t really tell you with certainty if a person has a concussion or not,” she said. “Therefore, we typically use multiple scales. One commonly used option is the King-Devick test of rapid number naming, in which the person reads numbers from left to right on a screen [as quickly as possible], and each screen gets progressively more difficult with regard to crowding. Because a person’s vestibular-ocular capabilities are affected by concussion, someone who is concussed will have a slower score on this test than at baseline. When you combine SCAT6, including the neuropsychometric screen and gait testing, with King-Devick, you get pretty close to 100 percent sensitivity along with very good specificity as well.”

Since the SCAT is ideally intended for use in the 72-hour window immediately following a suspected concussion, in 2023 the CISG also released the Sport Concussion Office Assessment Tool 6 (SCOAT6), designed for evaluating and managing concussion in the days and weeks after the acute post-injury period.

“This is the first time that we have had an office tool for helping to diagnose concussion versus persisting symptoms in the post-acute period,” Dr. Hainline said.

SCOAT6 includes a 10-word recall and digit backwards test, blood pressure and heart rate measurements, a neurologic examination and evaluation of cervical spine, timed tandem gait as a single task and a more complex dual task with three additional cognitive tasks, a modified vestibular ocular motor screening, delayed word recall, and a mental health and sleep screen.

Even though it is the first version of SCOAT, the authors dubbed it SCOAT6 to avoid confusion over having a SCOAT1 and a SCAT6. Both SCAT and SCOAT have pediatric companion versions for children under age 12.

Another major change in the field within the past two decades is the availability of specialized training for neurologists in the management of neurotrauma, including concussion. The fellowship Dr. Choe helps to lead at UCLA today did not exist when she was injured, or even when she was in medical school; in 2012, she became the first neurologist to complete UCLA’s fellowship and one of only a handful in the country at that time with specialized postgraduate training in neurotrauma and sports neurology.

Guidelines for the evaluation and management of concussion have also advanced in recent years. In 1997, the AAN issued its first set of sports concussion guidelines, which were based on the concussion “grading systems” common at the time. (The guideline was since retired.)

“We used to grade concussions as mild, moderate, or severe based on presenting features,” Dr. Choe said. “But now the field has moved more toward grading the likelihood that you had a concussion, based on mechanism of injury, presenting symptoms, and testing such as the SCAT6.” Newer versions of the AAN guideline, published in Neurology in 2013, incorporate more advanced understanding of the evaluation and management of concussion.

Imaging and Other Biomarkers
If the clinician suspects a skull fracture or bleeding in the brain, a CT scan of the head remains the gold standard for diagnostic imaging. But as concussions, by definition, do not manifest visible injury or bleeding in the brain with routine imaging, the role of imaging in concussion evaluation and management is limited.

“If you are concerned about moderate to severe TBI or skull fracture, or if the patient has a rapidly declining level of consciousness, then a head CT would be recommended, but that does not rule in or out concussion,” Dr. Starling said.

“Concussion is a diffuse injury to the brain in which whole networks are jostled,” she continued. “Even a standard MRI of the brain would not give us any additional information about that and is not recommended for the vast majority of suspected concussions unless examination abnormalities lead one to suspect a focal injury to the brain.”

Advanced imaging techniques, such as functional MRI and PET scans, are being studied in the setting of concussion and mild TBI.

“We are consistently finding abnormalities in those types of functional studies, which makes sense; on a gross anatomy level, a concussion is a problem of abnormal function in the brain in the setting of relatively normal brain structure,” Dr. Starling said.

“Once the research is more advanced and abnormalities are more consistently understood across studies, these types of imaging might be useful for prognosis among individuals for whom it’s very important to understand that,” she said. “But given the high number of people who have concussions and the fact that the vast majority of them recover within a month, even if advanced imaging moves from the research to the clinical arena, there’s never going to be a world in which most people with concussion get a functional imaging study.”

Researchers continue to seek biomarkers that might provide more objective testing for concussion as well as predict which patients with concussion will experience prolonged symptoms. The NCAA-Department of Defense Grand Alliance CARE Consortium, initiated in 2014, is the first prospective, longitudinal study of both concussion and repetitive head impact exposure.

It has enrolled over 55,000 study participants among NCAA student athletes and service academy cadets, including players from all 24 NCAA sports as well as a subgroup analysis of higher-risk sports such as football, ice hockey, lacrosse, field hockey, and soccer.

“One of CARE’s primary goals is assessing proteomic, genomic and neuroimaging biomarkers that might give us a more objective way to assess whether or not a person has had a concussion as well as predicting the length of their recovery,” Dr. Hainline said.

A systematic review from CISG, published in the British Journal of Sports Medicine in June, found that significant progress has been made toward validating advanced neuroimaging, blood and fluid-based biomarkers, genetic testing, and emerging technologies for potential clinical use in concussion diagnosis and prognosis.

“We’ve made great strides in optimizing these biomarkers and device technologies as an aid in diagnosis and assessment for concussion, but they’re not quite ready yet for widespread clinical use in sport,” said Dr. McCrea, one of the review’s lead authors.

“Two blood-based biomarkers do now have FDA clearance for clinical use in TBI for ruling out hemorrhage,” he noted. “Although that’s a different world than using such testing on the sideline in concussion, ultimately the availability of point of care testing is the pathway to clinical utilization. I believe these tools have enormous potential for use in civilian, military, and sport medicine environments as an aid in diagnosis for concussion and mild TBI.”

Research also suggests that certain premorbid factors, such as a personal or even a family history of psychiatric symptoms and migraine, may play a role in post-concussion syndrome (PCS) and recovery.

Researchers at Vanderbilt University Medical Center reported in a 2018 study in the Journal of Neurosurgery: Pediatrics that concussed high school athletes with a personal and family psychiatric history were more than five times more likely to develop PCS than controls, and even athletes with only a family history were over 2.5 times more likely to develop PCS than controls. Another study published in the Journal of Head Trauma and Rehabilitation in 2018 found that patients with a family history of migraine were 2.6 times more likely to present with post-traumatic migraine symptoms after concussion.

Radical Change in Management
One of the most radical changes in concussion practice over the past 20 to 30 years has been in its management once diagnosed. “Prior to the 1990s, systematic protocols for injury management and return to play after a concussion were seldom used. Athletes often returned to play during the same game or practice,” said Dr. McCrea. “Then there was a period of time when standard practice in managing a suspected concussion was what was called ‘cocoon therapy.’”

That’s what Dr. Choe was prescribed after her concussion during college: she was told to stay at home in a dark, quiet room and avoid exercise and stimulus. “You were supposed to stay away from school, work, and activity until you got better, usually about a week, and then re-emerge into your normal life,” Dr. Starling said.

But a study Dr. McCrea and colleagues published in Clinical Pediatrics in 2015 found that this approach was actually counterproductive. The control group included patients who returned to school and resumed activities that were symptom-limited; while they did not return to sports immediately or put themselves at risk of head injury, they participated in other normal activities. The intervention group, which adhered to five days of strict bed rest, was expected to do better—instead, they had more persistent symptoms and a longer recovery period.”

A meta-analysis of seven randomized trials published in Pediatrics in May confirmed and expanded on these findings, determining that concussion symptoms resolved more quickly in patients assigned to early return to sub-symptom aerobic activity or multimodal activity (aerobic activity plus visualization and coordination exercise) compared with those who had no prescribed activity.

“We do want to protect individuals from repeat injury, because we know that a second concussion on top of the first while the person is still recovering is highly dangerous,” Dr. Starling said. “But we want to get people back into physical and cognitive activity within a couple of days of the injury, and that is a significant paradigm shift.”

Today, protocols for return to activity after concussion are more standardized and more gradual. “We now have well-validated protocols for rehabilitation and gradual return to activity that allow adequate time for brain recovery,” Dr. McCrea said. “We used to manage concussion on a switch: the minute we thought you were ready to go, back you went to football practice. Now, we manage concussion on a dial: as you’re improving clinically, we gradually increase exertion and activity and ramp you up to return to unrestricted participation in sport over time.”

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