AAN: Easy Test May Point to Concussion

A simple clinical measure of reaction time may identify athletes who require evaluation for concussion, according to a study that will be reported at the American Academy of Neurology meeting in April.

A 20-millisecond increase from baseline reaction time correctly identified all but one athlete with a physician-diagnosed concussion.

The test employs an inexpensive device consisting of a rigid cylinder attached to a weighted disk. The test could easily be performed at the site of ongoing competition.

"Research has shown that reaction time is slower after a concussion -- even as long as several days after other symptoms are gone," said James Eckner, MD, of the University of Michigan in Ann Arbor. "The tests currently used require computers and specialized software."

As a potential alternative to sophisticated equipment, Eckner and coinvestigators developed the simple weighted-rod device and found it reliable and accurate in initial evaluations.

To continue their validation of the test, investigators recruited 209 members of the University of Michigan football, wrestling, and women's soccer teams at preseason physical examinations. During the reaction-time test, the weighted-rod was held a standard distance off the ground and then released. An athlete seated on a bench or chair caught the device as quickly as possible after its release.

Reaction time was calculated from the distance the rod fell before being caught, using the formula for a body falling under the influence of gravity.

Athletes who had physician-diagnosed concussions during the season repeated the reaction-time test within 72 hours of diagnosis.

Seven of the eight athletes who had concussions had prolonged reaction times compared with baseline values.

The athletes' reaction times averaged about 200 ms at baseline, increasing to an average of about 220 ms following their concussions.

Eckner said the test requires validation in a larger number of athletes before pronouncing it ready for routine use. However, he said, if the test's accuracy is corroborated in additional evaluations, its simple design would allow it to be used on the sideline or in a training room to identify injured athletes who require clinical evaluation for concussion.

"Because of its simplicity and low cost, this test may work well with youth athletes, where there is limited access to computerized testing of reaction time," said Eckner.

Conceivably, the test could be performed by a trainer or other nonphysician with appropriate instruction in how to conduct the test, Eckner allowed.