A physician at Northwestern Memorial Hospital in Chicago said Sen. Mark Kirk (R-Ill.) is doing very well and will stay in intensive care from between five days to a week.

Neurosurgeon Richard Fessler gave an update Tuesday on Kirk's condition, a day after he underwent surgery to relieve brain swelling.

Fessler said that Kirk has "slight facial paralysis on the left side" of his face right now. He said that was why Kirk is slightly slurring his speech. In his initial press conference on Monday, Fessler said that Kirk could lose motor functions on the left side of his face permanently. Fessler added that Kirk would not experience any mental impairment from the stroke.

"The senator is doing very well and I'm very happy with his progress and where his condition sits right now," Fessler said.

He said that Kirk is breathing on his own, responding to questions, and even asked for his BlackBerry.

"That means he was communicating and thinking about work," Fessler said.

Kirk suffered an ischemic stroke over the weekend and underwent surgery on Monday to relieve swelling in his brain. Doctors removed a four-inch by eight-inch part of the senator's skull. 

Sen. Joe Manchin (D-W.Va.) was scheduled to sit next to Kirk during President Obama's State of the Union address on Tuesday night. The Associated Press reports that Manchin will leave the seat empty in honor of Kirk.

The night before Kirk, 52, suffered his stroke, the Chicago Sun-Times reported that he seemed in fine health as he had been enjoying a beer and cheeseburger at the Billy Goat Tavern in downtown Chicago. 

—This story was updated at 2:19 p.m.