The 32-year-old Australian, who is in his 10th season of Super League after previous spells with Huddersfield and Bradford, was taken to hospital in a neck brace after being hurt in the Reds' 28-7 defeat by Bradford last Friday.
He was released later that evening after being cleared of any major injury but Salford coach Brian Noble says the club are determined to get to the bottom of the on-going problem before allowing him back on the field.
Nero, who sustained the injury in a clash of heads with team-mate Wayne Godwin, will sit out Sunday's game against Widnes, which will kick off the action on day two of the Magic Weekend at the Etihad Stadium, and is not guaranteed to play again.
"The great news is that Chris is fine and we're delighted about that but we have to take some serious decisions on his future," Noble said.
"When something like this happens, you have to examine the reasons for it.
"The medical people have to give us the right information and then we can sit down with Chris and discuss it.
"If he can play next week, he will, however, we don't take chances."
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