Vision testing an effective tool for detecting concussion on the sidelines

Sept. 11, 2015

Review article finds a test of rapid number naming detected concussion 86 percent of the time among youth, collegiate and professional athletes

A timed vision test that involves rapidly reading numbers off of cards can be a valuable sideline tool for detecting whether a concussion occurred while playing sports, according to a meta-analysis and systematic review led by NYU Langone Medical Center concussion specialists.

Researchers at the NYU Langone Concussion Center reviewed studies that involved athletes who sustained a concussion during sporting activities and found the vision test, known as the King-Devick test, was 86 percent sensitive in detecting whether a concussion had occurred, as confirmed by clinical diagnosis. When combined with rapid assessments of balance and cognition, the testing battery was able to detect 100 percent of concussions that occurred among athletes in the studies that measured this outcome.

The study was published Thursday, September 10, 2015, in Concussion.

"There is no diagnostic substitute for a medical professional when it comes to evaluating an athlete for concussion, but physicians are not always on the sidelines during practice or a game when an injury might occur," says senior study author Laura Balcer, MD, MSCE, Co-director of the NYU Langone Concussion Center and a professor of neurology, population health and ophthalmology at NYU Langone. "Our study shows that an easy to administer vision test is a simple, effective tool that empowers parents, coaches, trainers - and even physicians - on the sidelines to have a protocol for deciding if an athlete should be removed from play."

For the rapid number naming test, athletes are given a baseline test before the season starts where they are asked to read numbers as quickly as they can off a series of three reading cards while being timed with a stopwatch. People who don't experience a concussion or head injury tend to have faster reading times when tested again during the season; however, those who are tested immediately after they may have sustained a concussion experience slower times.

Vision is important in concussion diagnosis because the visual pathways have extensive connections throughout the brain, and disruptions in these pathways could suggest a brain injury occurred. Previous studies have shown worsening scores on rapid number naming tests correlate with neurological conditions including Parkinson's disease, multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS).

Balcer and her colleagues conducted a meta-analysis review of 15 previously-completed studies where a rapid number naming test was utilized. All the studies were conducted on athletes, and all concussions were defined by a witnessed or reported blow to the head with neurological symptoms.

The review included 1,419 athletes, 112 of whom sustained a concussion. Professional hockey players, along with youth, collegiate and amateur players of football, hockey, soccer, lacrosse, basketball, boxing and rugby were among those studied.

Concussed athletes on average completed the King-Devick test 4.8 seconds longer than their baseline score, whereas non-concussed athletes improved their score by an average of 1.9 seconds. The test detected 96 out of 112 concussions (86 percent), and showed 90-percent specificity in distinguishing a concussed athlete versus a non-concussed, healthy control subject. Overall, if an athlete had a worsening in their time score compared to their baseline reading, they were five times more likely to have sustained a concussion.

Some studies included the review utilized other tests including the SCAT3 symptom checklist and timed tandem gait (walking) test, and importantly, a worsening in scores of at least one of the three tests was observed in 100 percent of concussed athletes.

"This tool as part of a simple battery of tests assessing cognition and balance can raise a flag for those athletes that require follow-up with a medical professional," says study co-author Steven Galetta, MD, the Philip K. Moskowitz, MD Professor and Chair of Neurology at NYU Langone Medical Center. Dr. Galetta, himself a former collegiate athlete, added, "In the heat of a game, there is a lot of chaos and confusion on sidelines, so anything that helps eliminate guesswork is needed."

A March study led by Dr. Galetta and Dr. Balcer, published in the Journal of Neuro-Ophthalmology, found the King-Devick test effective at helping to detect a concussion in student athletes as young as 5 years old.

A concussion is caused by a force transmitted to the head as a result of a direct blow to the body that results in new neurological symptoms. An estimated 4 million sports-related concussions occur each year in the United States each year, with long-term consequences on brain function becoming an increasingly prominent concern among those who play contact and collision sports.

Adapted by MNT from original media release

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What is concussion? What is mild traumatic brain injury (MTBI)?

Concussion is also known as mild brain injury, mild traumatic brain injury (MTBI), mild head injury and minor head trauma. Some experts define concussion as a head injury with temporary loss of brain function, which can cause cognitive, physical and emotional symptoms. Concussion may also be defined as an injury to the brain generally caused by a jolt or blow to the head - in the majority of cases the individual does not lose consciousness. 

According to Medilexicon's medical dictionary, concussion is "An injury of a soft structure, as the brain, resulting from a blow or violent shaking."

In sports medicine the term concussion is commonly used, while in general medicine MTBI (mild traumatic brain injury) may be used as well. Lay people are more familiar with the term concussion.

According to the Brain Injury Association of America males are twice as likely as females to sustain a brain injury. Those at highest risk of a brain injury are males aged 15 to 24 years. People who have had a brain injury are more likely to experience a subsequent brain injury. In 2008 there were 351,992 sports-related head injuries that were treated in hospital emergency rooms in the USA, according to the U.S. Consumer Product Safety Commission. 

Researchers from Toronto University reported that children take longer to recover from second or third concussions, compared to those with a first concussion. They reported their findings in the journal Pedatrics (June 2013 issue).

Researchers from the Centre de recherche en neuropsychologie et cognition, Université de Montréal, Canada found evidence that athletes who were concussed during their earlier sporting life show a decline in their mental and physical processes more than 30 years later.

On Monday, March 18th, 2013, the American Academy of Neurology launched:

• The "Updated Sports Concussion Guideline" which states that athletes should be removed immediately from play if concussion is suspected.


• An app called "Concussion Quick Check" which is available for iPad, Android, IOS (Apple) and some other mobile communication devices. It is aimed at helping trainers, coaches, parents and other athletes quickly determine whether somebody has suspected concussion and needs to see a doctor.

What are the causes of concussion? 

The brain floats in cerebral fluid which protects it from jolts and bumps. A violent jolt or a severe blow to the head can cause the brain to bump hard against the skull. This can result in the tearing of fiber nerves as well as blood vessel rupture under the skull, leading to an accumulation of blood.

• Automobile accidents - concussions commonly occur from severe jolts to the head; this can happen when a vehicle suddenly loses speed or stops dead, causing the brain to jar (bash, bump hard) against the skull. 


• Sports injuries - especially contact sports, such as martial arts, boxing, rugby, American football, and hokey. Non-contact sports such as snowboarding and skiing as well. 


• Falls - any fall that results in a blow to the head or a severe jolt. The majority of concussion cases in very young children and elderly individuals in the USA and UK occur as a result of a fall in the home. 


• Horseback riding accidents - there were 11,749 cases of head injuries resulting from horseback riding accidents in 2008 in the USA, according to the U.S. Consumer Product Safety Commission. 


• Playground accidents - especially in playgrounds that do not have proper soft underlays. 


• Cycling accidents - according to the U.S. Consumer Product Safety Commission there were 70,802 cases of head injuries that resulted from cycling accidents. 


• Assaults - 11% of traumatic brain injuries in the USA are caused by assaults (people being attacked), according to the CDC (Centers for Disease Control and Prevention)
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