Portable Optical Imaging Tool Designed for Concussion Evaluation

That report, published in the July 2014 issue of the journal Brain Imaging and Behavior, led to additional research out of University of Pittsburgh (Pitt) Medical Center (UPMC; PA, USA) that examined the brain during dual cognitive-balance performance in children following concussion.

The fNIRS unit works similar to a pulse oximeter for the brain. It gauges blood flow to the brain by sending light signals from sensors mounted in a 3-pound head-cap, and then producing images of blood oxygen changes representing brain activity by recording the absorption of light at different colors. The fNIRS generated readouts while participants wearing the head-cap took a computerized neurocognitive test and matched the test in revealing the brain's struggles to complete specific cognitive tasks.

“We hypothesize that cerebral blood flow is affected post-injury, and brain processing is going to be less efficient,” explained Anthony Kontos, PhD, assistant research director, UPMC Sports Medicine Concussion Program and assistant professor, Pitt department of orthopedic surgery. “If you’re performing a memory task or reaction-time task, it would require activation—more blood flow, more oxygen needed—in certain areas of the brain specific to that task. However, we found decreased and more spread out activation in the concussed group. In other words, their injured brains were less efficient and strained to get from elsewhere in the brain the resources necessary to perform cognitive tasks.”

“We knew what brain areas normally should light up,” added Theodore Huppert, PhD, assistant professor, Magnetic Resonance Research Center, Pitt department of radiology and Swanson School of Engineering. “From our data set, we had on average decreased brain activity and more diffuse brain activity, where more areas of the brain were needed to accomplish the task because the usual areas weren’t as efficient.”

This preliminary study included nine people between ages 18 and 45 who were symptomatic within 15 days to 1½ months of a sports-related concussion. Researchers compared them to five people who were uninjured. The fNIRS scans indicated that the concussed brain activated at a lower threshold and drew from a wider area—a distinct contrast from earlier functional magnetic resonance imaging (fMRI) studies using concussion patients. Furthermore, the decrease in oxygenated blood flow and lower test performance were detected during certain, more cognitively strenuous aspects of neurocognitive testing: word memory, design memory, and symbol matching.

“It’s a portable and fairly inexpensive imaging device compared to MRI; and most important, it allows us to combine both spatial and temporal information, meaning what is going on in a specific area of the brain and when the activation is occurring,” Dr. Kontos said. “It’s not just location. It’s not just timing. It’s both.”

A wireless fNIRS device is expected on the market soon, availing it for further research in a clinical and possibly even a sideline concussion setting, according to the investigators. However, Dr. Kontos emphasized the utility of the current iteration, “You can wear this while doing neurocognitive testing, you can wear this during balance-testing, you can even wear it while doing exertional testing, like on a treadmill. It’s useable in an environment for sports-related concussion.”

“In the past decade and a half, many in the field of concussion science have tried to find an imaging tool that could help us in a clinical setting, and failed to find anything with consistency,” stated Michael Collins, PhD, director, UPMC Sports Medicine Concussion Program. “This preliminary study, although small, showed us where in the brain a patient is affected and to what cognitive extent. It was enough evidence for us to keep pushing further with this potential tool.”

The fNIRS study employed ImPACT, a computerized neurocognitive test battery designed to evaluate mild traumatic brain injury. The technology was developed by ImPACT Applications, Inc. (Pittsburgh, PA, USA).

In a separate study, a meta-analysis published in the March 2014 edition of the Journal of the International Neuropsychological Society, Rock Braithwaite, EdD, a professor from the department of kinesiology and recreation administration, Humboldt State University (Arcata, CA, USA), synthesized all existing research using the four major computerized neurocognitive tests for concussion: Headminder, CogSport, Automated Neuropsychological Assessment Metrics (ANAM), and ImPACT.

In what is considered the largest statistical review of published computerized concussion testing to date, involving 37 studies and 3,960 participants all within the first week of sustaining a concussion, the investigators produced two key findings: (1) Middle-school and younger high-school students displayed more pronounced cognitive effects and greater performance deterioration according to neurocognitive testing after a concussion than their senior high-school and college-aged counterparts. (2) ImPACT demonstrated the strongest performance for identifying cognitive impairment because it measured the types of tasks that this meta-analysis analyzed as being most effective in detecting such postconcussion issues: processing speed, verbal memory, visual memory, and recall.

“ImPACT found the largest effects for individuals who had been concussed, across all outcomes,” said Dr. Braithwaite, who initiated the idea for this study. “Memory, processing speed, recall… ImPACT was able to better detect changes compared to the other computerized tests.”

Dr. Kontos, a coauthor on the meta-analysis along with Drs. Elbin and Dakan, concurred with Dr. Braithwaite that their study is an important first step. “There is not a lot of good research out there involving many of these tests, and most of the existing research uses the ImPACT test,” said Dr. Kontos. “We need more research on the effectiveness of these other tests in patients with sports-related concussion.”

Related Links:
University of Pittsburgh Medical Center
ImPACT Applications 
Humboldt State University