Tottenham's Jan Vertonghen leaves the field after sustaining a head injury

FIFPro wants stakeholders to explore the possibility of allowing a temporary substitute to accommodate 10-minute head injury assessments.

Tottenham's Jan Vertonghen suffered a head injury during Tuesday's Champions League defeat to Ajax, but was allowed to return to the field before it became clear he could not continue.

FIFPro, the worldwide representative for professional footballers, has now called for an independent doctor to assist the club doctor and assess whether a player with a head injury should be allowed to return to the pitch.

The tool used to assess concussions is not effective when used in just three minutes, the length of time UEFA allows for players to undergo assessment.

1:15 Tottenham manager Mauricio Pochettino says Spurs’ medical staff followed concussion protocols after Jan Vertonghen suffered a head injury against Ajax Tottenham manager Mauricio Pochettino says Spurs’ medical staff followed concussion protocols after Jan Vertonghen suffered a head injury against Ajax

Dr Vincent Gouttebarge, FIFPro's chief medical officer, called this time limit "ridiculous" and explained why the need for temporary substitutions is so pressing.

"The problem is you need at least 10 minutes to apply properly this assessment tool and in football the medical team is given only three minutes to complete it," Dr Gouttebarge told Sky Sports News.

"This is a ridiculous measure with regard to the 10 minutes needed to thoroughly apply the tool and the protocol available.

"We know from a scientific point of view that the first set of questions in the tool in isolation, as they are used in football, are not valid to identify concussion.

Vertonghen was helped off the pitch

"With regard to yesterday's event, we have to be cautious of blaming the medical team for every concussion because it is not easy.

"We need to facilitate the medical team in this exercise. The three minutes given to the medical team to make an on-field assessment of the concussion is just ridiculous.

"FIFPro has been very clear. We need to educate not only the players, but also the technical and medical staff properly."

FIFPro has been working on improving concussion management since Hugo Lloris was injured in a 0-0 draw with Everton at Goodison Park in November 2013.

That incident led the FA to change its procedure, meaning team doctors could overrule managers who wanted their player to return to the field.

1:15 Tottenham manager Mauricio Pochettino says Spurs’ medical staff followed concussion protocols after Jan Vertonghen suffered a head injury against Ajax Tottenham manager Mauricio Pochettino says Spurs’ medical staff followed concussion protocols after Jan Vertonghen suffered a head injury against Ajax

Tottenham manager Mauricio Pochettino had to put his arm round Vertonghen during Tuesday's game and support the defender before the Belgian was carried away after appearing to retch by the touchline.

Tottenham's decision to allow Vertonghen to attempt to continue playing had been taken after club doctors "followed concussion protocols", according to Pochettino.

Peter McCabe, chief executive of brain injury charity Headway also called for an independent doctor to take stressful decision-making powers away from club staff.

"You need to have timeouts without disadvantaging the team and the other thing we think is really important is that there should be an independent doctor involved in the decision-making process because the pressure on club staff with a huge game of that magnitude is intense," McCabe told Sky Sports News.

"We think that having somebody independent of the club, whose job it is to focus entirely on the health and wellbeing of the player would be really important and those simple measures would make a big difference."

1:44 Consultant neurosurgeon Mr Peter Hamlyn explains signs of concussion and the procedure for safely dealing with footballers when head injuries occur Consultant neurosurgeon Mr Peter Hamlyn explains signs of concussion and the procedure for safely dealing with footballers when head injuries occur

Mr Peter Hamlyn, a consultant neurosurgeon and expert in sports medicine, said many concussions are difficult to identify quickly, saying that Vertonghen could well have appeared fine initially.

"Sometimes it's obvious, somebody has lost consciousness," Mr Hamlyn told Sky Sports News. "There are then many, many concussions, indeed most, where there isn't a loss of consciousness.

"The signs can be anything from a player not behaving appropriately, perhaps running in the wrong direction, to performing very slowly.

"When they come off the pitch, the questions you ask them are about orientation - do they know who they are, what they are, what they're doing, which stadium we're in, what the score is?

"Whether you go back on has to be partly up to the player and partly up to the officials.

"Most of the time the players do want to go back on, even if it's not in their best interests.

"Vertonghen could have passed the screening protocol, went back on and the symptoms became more apparent as he exercised."