By GEORGE JOHNSON -- Calgary Sun. VANCOUVER -- Valeri Bure's return is uncertain.
 Ditto, Ron Stern's.
 Bure woke up yesterday complaining of headaches, the aftermath of a concussion suffered Tuesday against Tampa Bay.
 He'll undergo the standard neuro-psych test initiated by the league, and the path back to playing goes through three stages.
 "Number 1," explained physiotherapist Terry Kane, "he'll ride the bike for a couple of minutes with his heart at 120 beats. If he does that and 24 hours later has had no headaches, we go up to 150 beats. Passing that, he can begin light skating, to be followed by at least two full practices with the team."
 Given that timetable, and limited practice opportunities during this long trip, the earliest Bure might return to the lineup would be next Wednesday in Pittsburgh.