The Argentina striker was forced off in the closing stages of the Serie A encounter after a heavy challenge from defender Marco Andreolli and received oxygen as he was carried from the pitch.
The Azzurri confirmed on Saturday that the former Real Madrid forward suffered an impact injury to his ankle, which has put his involvement in next week's Coppa Italia final in serious doubt.
"Strong blunt trauma to the right tibia," a statement on the club's official website read.
"This the outcome of examinations submitted this morning on Gonzalo Higuain after the collision during Inter-Napoli with Andreolli.
"Clinical tests have confirmed what was first diagnosed yesterday.
"[Higuain] today had therapy and his condition will be evaluated in the coming days."
Argentina coach Alejandro Sabella will also take a keen interest in the fitness of Higuain, who is expected to be a part of his World Cup plans.
The 26-year-old has scored 24 times in 44 games since joining Partenopei last August for a reported €40 million and has helped them to third in Serie A so far this campaign.