Seedsman, who turns 31 next week, has been put on the Crows' inactive list after also missing all of last year due to concussion.
He copped a knock to the head in a marking contest at training in December 2021 and has since been suffering with migraines and nausea.
"We have come to the realisation that Paul will not be in a position to play this year given he is still experiencing symptoms," Adelaide's head of football Adam Kelly said in a statement on Tuesday.
"To Paul's credit, he came forward and acknowledged this now so the club can identify someone in the pre-season supplemental selection period that we can provide an opportunity to.
"As an industry we understand concussion is a serious and complex injury and while on the inactive list Paul will continue to work closely with our doctors and medical staff as well as concussion experts."
The decision on 132-gamer Seedsman creates a second vacant spot on Adelaide's playing roster for the looming season after 21-year-old Fischer McAsey walked away from the sport a week ago.
Former Collingwood midfielder Tyler Brown is favoured to take one of those spots after joining the Crows this week for a trial training period.
The 23-year-old Brown was delisted late last year after spending five seasons with the Magpies.
Supplemental list selections must be made by February 15.
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