Nansen has been ruled out of recent European Challenge Cup fixtures with concussion and Jackman has revealed Dragons are now liaising with Samoa over his availability.
“Brandon has not yet recovered from concussion which puts his November series in doubt,” he said.
“We are liaising with the Samoa team, but it will be hard for him having not played recently.
“He hasn’t passed the relevant tests yet. He is getting better, but I’ll be surprised if he goes at the moment.”