Sources tell Mortensen that the fourth visit concluded with the doctor telling Gannon "it's over" -- with the doctor alluding to "it" as meaning the quarterback's season.
Gannon said he would make an announcement about his football future sometime Monday, according to a San Francisco Chronicle report. The newspaper predicted that the player likely would submit to going on injured reserve but that Gannon might not delay his retirement until he had explored all his options -- financial and otherwise.
He has received mixed messages from other specialists -- one doctor told him the season, and maybe his career, is probably all but over. But another doctor, one the Raiders referred him to, said Gannon might be OK in six to eight weeks.
The 17-year veteran fractured a vertebra at the base of his neck in a helmet-to-helmet collision with Tampa Bay Buccaneers linebacker Derrick Brooks on Sept. 26.
Team officials have been careful in their public remarks about Gannon's future, both for the short and long term, but there have been hints he will not play again in 2004 and that the injury could end his long and productive career.
The Raiders are still in a holding pattern before determining whether to place him on injured reserve for the second straight season.
Information from The Associated Press was used in this report.