Eye-tracking device measures severity of concussion and brain injury

12 February 2015

A novel eye-tracking device can effectively measure the severity of concussion or brain injury in patients presenting to emergency departments following head trauma. The simple and objective diagnostic tool could also be developed for use on the sidelines at sporting events.

It is a significant improvement on the only field 'tool' available at the moment — a medic moving a finger in front of the injured person's face. A better method to evaluate head injuries in the field is badly needed as shown by discussions following many sports events when injured players returned to the field of play after head injuries.

A recent example is Welsh rugby player George North who was hit on the head twice and appeared to be knocked out on the second incident during the international against England on 6 February. He was allowed to return to play because the team medics had not seen that incident, but passed him as fit. Doctors say he has not suffered any ill-effects since but he has not been picked for the next game against Scotland on 15 February to give him an extended period of recovery.

The eye-tracking technology used in this study was originally developed by lead investigator Dr Uzma Samadani and colleagues at the Cohen Veterans Center to assess eye movement in veterans of Middle East conflicts suspected of suffering from traumatic brain injury (TBI), concussion or other forms of brain injury.

In this new study, researchers studied trauma patients in the emergency department at Bellevue Hospital Center in New York City.  The patients watched a 4-minute video playing inside of an aperture moving around the perimetry of a video monitor while a camera recorded eye movements.

A patient watches a video while eye movements are tracked by a camera
A patient watches a video while eye movements are tracked by a camera

The study showed that 13 trauma patients who had hit their heads and had CT scans showing new brain damage, as well as 39 trauma patients who had hit their heads and had normal CT scans, had significantly less ability to coordinate their eye movements than normal, uninjured control subjects. Twenty-three trauma subjects who had bodily or extremity injuries but did not require head CT scans had similar abilities to coordinate eye movements as normal uninjured controls.

Among patients who had hit their heads and had normal CT scans, most were slightly worse at 1-2 weeks after the injury, and subsequently recovered about one month after the injury. Among all trauma patients, the severity of concussive symptoms correlated with severity of disconjugacy. The study has been published online in the Journal of Neurotrauma.

"Concussion is a condition that has been plagued by the lack of an objective diagnostic tool which, in turn, has helped drive confusion and fears among those affected and their families," says Dr Samadani, who is also assistant professor in the Departments of Neurosurgery, Psychiatry, Neuroscience and Physiology at NYU Langone. "Our new eye-tracking methodology may be the missing piece to help better diagnose concussion severity, enable testing of diagnostics and therapeutics, and help assess recovery, such as when a patient can safely return to work following a head injury."

The eyes have served as a window into the brain, with disconjugate eye movements — eyes rotating in opposite directions — considered a principal marker for head trauma as early as 3,500 years ago. Current estimates by optometrists suggest that up to 90% of patients with concussions or blast injuries exhibit dysfunction in their eye movements.

Unfortunately, the "state-of-the-art" tool to detect eye conjugacy is asking a patient to follow along with a physician’s finger, according to Dr Samadani, who also serves as co-director of the Steven & Alexandra Cohen Veterans Center for the Study of Post-Traumatic Stress and Traumatic Brain Injury at NYU Langone.

"Traumatic brain injury is one of the most common causes of neurologic morbidity in the world today," says Dr Richard Ellenbogen, the Theodore S Roberts Endowed Chair and professor and chairman of the Department of Neurological Surgery at University of Washington Medicine and co-chair of the Head, Neck and Spine Committee of the National Football League. "Sports concussion, on the mild end of the spectrum of TBI, has captured the fascination of both the public and media. Since concussion affects all ages, both genders and occurs in all sports, being able to make the diagnosis quickly and accurately is essential. The challenge physicians have in identifying concussion is that the diagnosis is often based on self-reported symptoms."

"Dr Samadani and her colleagues have come up with a novel and objective manner of assessing patients with a suspected TBI," he added. "The beauty to their method is that it is non-invasive, reproducible and easy to perform on the sidelines or in the field. It provides a simple and elegant method of being able to assess the functional deficits that occur with TBI, and thus help the physician make a rapid and accurate diagnosis.

"By tracking eye movements, they have been able to quantitatively assess the function of the brain. Their new approach will hopefully identify those patients who may be missed by basing the evaluation simply on subjective complaints. This work adds an important dimension to our ability to provide safe, rapid and accurate care to those who suffer TBI in sports or with daily life activities."

This new study of non-military, civilian trauma patients visiting the emergency department builds on recent research conducted by Dr. Samadani, supported through the Cohen Veterans Center, which found that the use of this novel eye-tracking technology could reveal oedema, or swelling, in the brain as a potential biomarker for assessing brain function and monitoring recovery in people with head injuries.

That study, published Dec. 16 in Journal of Neurosurgery, looked exclusively at military veterans. Dr Samadani’s future work aims to replicate eye-tracking’s diagnostic potential for head injuries on a larger scale in Iraq and Afghanistan veterans with post-concussive syndrome and post-blast military brain injury.

Estimates from the Centers for Disease Control and Prevention state about 2.5 million US emergency department visits were associated with traumatic brain injury in 2010, with rates increasing by about 70% over the previous decade. Currently there is no tool seen as a gold standard for diagnosing concussions, and imaging tests like CT-scans and MRIs are ineffective in the absence of structural damage to the brain.

"Two patients who suffer a head injury and present with virtually-identical CT-scans might have completely different symptoms," Dr. Samadani points out. "That’s where eye-tracking can help objectively reveal when one patient may be much more affected by a concussion than another."

Also lending third-party support for Dr. Samadani’s research is M.

Dr Sean Grady, the Charles Harrison Frazier Professor and Chairman of the Department of Neurosurgery at the Perelman School of Medicine at the University of Pennsylvania, commented, "The importance of this study is that it establishes a reliable test and a 'biological' marker for detecting concussion. Since concussion can occur without loss of consciousness, this can be particularly important in sideline evaluations in athletics or in military settings where individuals are highly motivated to return to activity and may minimize their symptoms. More work is needed to establish its sensitivity and specificity, but it is very promising."

Dr Samadani has submitted patents describing the technology utilized in this paper. These patents are owned by NYU and the VA and licensed to Oculogica Inc., a company co-founded by Dr. Samadani and co-investigator Robert Ritlop.

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