André Villas-Boas has angrily defended his decision to allow Hugo Lloris to continue playing against Everton on Sunday, despite the goalkeeper appearing disoriented after being hit on the head by Romelu Lukaku's knee as the pair challenged for a ball.

Tottenham Hotspur have been widely criticised for not substituting the player but Villas-Boas insisted the club did nothing wrong and accused "incompetent people" of turning on Spurs solely to attract attention to themselves. Villas-Boas also said it was "remarkable" Lukaku's role in the incident has not been questioned further and suggested the Everton striker could have avoided the clash.

Tottenham originally intended to replace Lloris with Brad Friedel after the incident but the Frenchman demanded to play on and, after examination on the pitch by the club doctor, Shabaaz Mughal, and club physiotherapist, Geoff Scott, Villas-Boas let him do so. That decision has since been condemned by, among others, the Professional Footballers' Association, the international players' union, Fifpro, Fifa's chief medical officer, Professor Jiri Dvorak, and the head injury charity Headway, who described the club's actions as "dangerous and irresponsible". However, Villas-Boas remains unrepentant.

"I stand absolutely by the decision that I took and the decision that the medical department has taken following the checks that they made on the player, all of which were according to the book," he said. "I stand by the decisions that gave us the green light for the player to continue. I have nothing else to say regarding that matter. I registered the fact that a couple of people have taken this opportunity to find a chance to get themselves publicised, people who have had no experience on the pitch whatsoever in this type of situation."

As far as the club are concerned, Lloris did not lose consciousness and was not concussed as a result of the blow to the head. Villas-Boas suggested it is wrong to question the responsibility of the same medical staff whose actions helped save the life of Fabrice Muamba when the former Bolton Wanderers player collapsed from cardiac arrest during an FA Cup tie at White Hart Lane two years ago.

"Two persons and the medical department that two years ago saved the life of a player on the pitch has been completely forgotten, poorly treated and badly respected by lots of opinion-makers. What is extremely disappointing is the fact that two persons – a great doctor and a great physio who saved the life of Fabrice Muamba – were put into question by lots of incompetent people and people who have no experience on the pitch, in the action, in the moment. That is extremely serious and disappointing."

Lloris underwent a precautionary brain scan on Sunday night, during which nothing irregular was detected. Nevertheless, the incident ignited a debate regarding the effectiveness with which footballer clubs tend to deal with head injuries, with critics suggesting that other sports handle them with more appropriate prudence. Villas-Boas said any comparison between the Lloris incident and others was spurious. "My medical department has followed the Premier League guidelines for this type of situation, that's the only thing I can tell you," he said. "The situation is obviously not comparable to NFL situations, rugby situations or Petr Cech's situation. It astonishes me that you try to put this in the same mould as situations that happened in the past. We have all the indications that the player is OK and we don't see incidents like this happening again."

However, the possible delayed effects of concussion were demonstrated when South Africa's Graeme Smith withdrew from the one-day international series against Pakistan on Wednesday and was advised to rest for at least two weeks. Smith was hit on the right temple on the second day of the second Test and the team manager Dr Mohammed Moosajee said: "Graeme was symptom-free after the blow except for a mild headache and tests at the time allowed him to continue playing. However, seven days post-injury, during the second ODI in Dubai he started complaining of blurred vision, which progressed to dizziness, unsteadiness on his feet and difficulty focusing.

"The MRI scan was clear, however it is in keeping with the assessment of post-concussion syndrome, which is usually a clinical diagnosis. Post-concussion syndrome can be described as a collection of symptoms that some people develop after they have experienced a minor traumatic brain injury otherwise known as concussion.

"Graeme will leave the tour on Thursday and has been advised a rest period of at least two weeks by the medical team. He will continuously be monitored in the interim."

Villas-Boas added it was "remarkable" that Lukaku, who injured his knee during the clash, has not come under more scrutiny for his role in the incident. The Portuguese, who was Chelsea manager when Lukaku joined that club from Anderlecht, claimed the striker could have moved his knee to prevent it hitting Lloris and said he was saddened the Belgian has not made contact with the goalkeeper since Sunday to check on his wellbeing.

"I want to believe that Lukaku's leg was not left late to clash into Hugo's head. I find it remarkable that through all of this amount of publicity that this incident has got nobody has actually dedicated themselves to finding out if he could have avoided the goalkeeper and I am disappointed that Lukaku hasn't contacted Hugo.

"Lukaku is a fantastic footballer and I don't question his integrity or his human side. We had a warm hug on the pitch before the game, so I have maximum respect for him and I think he has for me but amid all this negative excitement I find it surprising that no time was lost to actually study the incident. I don't want to question Lukaku. He's a young player and wonderfully gifted but I think he could have jumped over perfectly."

On Wednesday night, Headway reiterated their stance that Lloris should have been substituted. "The views of a number of leading experts from both within the game and outside of it … are all aligned on this issue and agree that if there is any sign of concussion, a player should be removed from the game," a statement from the charity read.