Swelling in Sen. Mark KirkMark KirkHigh stakes as Trump heads to Hill Five things to watch for at Trump-Senate GOP meeting Giffords, Scalise highlight party differences on guns MORE's (R-Ill.) brain has "subsided" and doctors reattached part of his skull that had been removed to relieve the pressure.

"The swelling in Senator Kirk's brain has subsided and this morning we were able to reattach the portion of his skull that had been removed following his stroke. This is an important milestone in his recovery and a step toward the next phase, rehabilitation. He remains in good condition," Northwestern Memorial Hospital neurosurgeon Richard Fessler said Wednesday. 

In late January Kirk suffered a stroke and has been recovering since. Fessler has said that Kirk's recovery was coming along as expected.

On Monday the neurosurgeon said that the junior senator's condition had been upgraded to "good" and that over the past weekend he saw his family and watched the Super Bowl.

Fessler has previously said that the senator was likely to recover in a matter of weeks or months. He also said that Kirk would likely have some motor impairment on the left side of his body, but would otherwise be fine.