The Argentina international collided with Dutch opponent Georginio Wijnaldum when competing for a header in a semi-final at the competition in Brazil.
Despite stumbling to the ground and appearing severely dazed after the innocous collision, Mascherano continued to play and inspired his nation to a penalty shoot-out win.
Uruguay's Alvaro Pereira suffered a similar injury against England earlier in the tournament while Tottenham goalkeeper Hugo Lloris suffered concussion in a Premier League clash with Everton last year. Both also played on.
Headway expressed concern at the fact Mascherano was allowed to continue playing and called on FIFA to enforce their guidelines on the issue more rigorously.
"On a big stage like the World Cup, it's incredibly hard to understand how there could be two different players throughout the course of a tournament who have been allowed to continue when they have seemingly been knocked out or suffered a concussive injury," a spokesperson told Perform.
"There needs to be some very serious questions asked of FIFA for how they have allowed this situation to happen.
"The FIFA guidelines suggest that if a player suffers a concussion or if there's a risk of concussion a player should be taken from the field and not allowed to return.
"That's FIFA's own guidelines and if you look back to the Hugo Lloris situation, you had FIFA executives coming out and saying these sorts of things.
"Yet on the biggest stage - the FIFA World Cup semi-final - you have a player that is clearly in distress seemingly being allowed to overrule the doctors and return to the field.
"It cannot be that a player is can make that decision - it has to be a medical decision and [doctors] have to be given the power to overrule both players and managers."
World Footballers' Association FIFPro also urged FIFA to take action following the Pereira incident - asking football's governing body to "conduct a thorough investigation into its own competition concussion protocol".
