The incident occurred while the Blues were on the power play. As Backes turned out of the corner in the Blues' zone with the puck, Seabrook laid a huge hit on him while his head was down.
As you might expect, a scrum ensued and officials tried to settle the two teams down. Backes was very slow to get up, and had trouble standing when he finally did. Trainers escorted him off to the quiet room for evaluation. The Blues have not given an update on his status.
Meanwhile, Seabrook was given a five-minute major for charging and a game misconduct. You can expect the NHL Department of Player Safety to give him a call this week.