Table 1.

Definition of video signs

Concussion sign	Definition
Clutch or shake head	The player holds his head or face in the palm of his hand or hands, or the player rubs or shakes his head in a manner that appears to demonstrate they are experiencing discomfort (i.e., not just wiping his face).
Slow to return to feet/play	Player took longer than usual to return to his feet (e.g., remained on the ground, got to his knees or to his haunches, and waited momentarily before standing), in the absence of another player holding him down.
Gait ataxia (wobbly legs)	Unable to stand steadily unaided or walk normally. Appears “clumsy”. Upon standing and walking the player has unsteadiness, wobbly legs, balance problems, stumbles or falls over, drags his feet, or cannot walk straight independently.
Blank/vacant stare	The player is not visually focused on doctor/trainer when being spoken to, or assessed and asked to attend, and/or the player appears to be looking off into the distance. The player’s face is expressionless.
Evidence of unresponsiveness	The player’s body goes limp/floppy, the player loses control of muscles, the player does not protect (i.e., brace) himself when falling (e.g., ragdoll-like appearance). The player remains/lies motionless on the ground for a period of time longer than expected, or the player shows a lack of visible responsiveness to verbal stimuli.
Post-impact seizure	Tonic posturing—stiffening of limbs; or clonic movements—involuntary repetitive contraction and relaxation of the muscles, could include jerky movements, or shaking/convulsion of upper and/or lower limbs, or body.