Sen. Mark Kirk underwent "successful" surgery Monday morning to relieve brain swelling after suffering a stroke over the weekend, a spokesperson for the Illinois Republican said.
Saturday, the 52-year-old checked himself into Lake Forest Hospital, where doctors discovered a separation in his carotid artery.
Later, when Kirk was transferred to Northwestern Memorial Hospital in Chicago, doctors determined the lawmaker had a stroke in the right side of his brain.
"What that means is it will affect his ability to move his left arm and possibly his left leg," explained Dr. Richard Fessler, the neurosurgeon at Northwestern Memorial who performed the surgery.
Still, surgeons declared Monday's operation a success and seemed optimistic that the Chicago lawmaker would recover.
"Due to his young age, good health and the nature of the stroke, doctors are very confident in the senator's recovery over the weeks ahead," Kirk's office said in a statement.
Kirk won President Barack Obama's Illinois Senate seat in a close 2010 race against Democrat Alexi Giannoulias.
"It's hard to imagine that anything could slow him down for long," The Courier-News quoted Rep. Judy Biggert, R-Ill. "All of us in the delegation are pulling for his full and speedy recovery."