The player was stretchered off the Emirates pitch after a coming together between himself and Hammers skipper Mark Noble and was awaiting an x-ray to assess the extent of the injury.
A statement on Arsenal's website reads: "We are hoping that Mo will available for Arsenal again this season and we are keeping in regular contact with the Egyptian Football Association."
"It’s an ankle problem that is very painful," manager Arsene Wenger told reporters after the match, as quoted by Metro. "Overall I believe that we have to wait until the X-ray to know a little more about it. But Thursday will be too soon for him."
This does come at a very bad time for the club and player as they have a Europa League tie against Atletico Madrid coming up, with the first leg set for Thursday.
Meanwhile, Liverpool star Mohamed Salah, who was named PFA Footballer of the Year on Sunday evening, has sent a heartwarming message to his compatriot via Twitter. He tweeted: "May peace be upon you, Nino, God willing."
Given the latest revelation, Elneny's World Cup chances are believed to be in serious doubt. But the Gunners, who could be galvanized by Wenger's resignation announcement, do look strong enough to provide sufficient cover for the stricken Egyptian.