It began Saturday with dizziness and a headache on a drive from Highland Park to Chicago, and escalated until surgeons removed a 4-by-8-inch portion of U.S. Sen. Mark Kirk's skull late Sunday to alleviate brain swelling.
That surgery, after a stroke Kirk suffered, left doctors hopeful Illinois' freshman senator will recover full mental abilities. But they said chances he'll regain full use of his left arm and leg are "not great."
Kirk is now resting at Northwestern Memorial Hospital in Chicago. As of Monday afternoon, even top members of his staff had not yet seen him.
The stroke came just hours after Kirk and his close-knit staff met for burgers and beer Friday evening at Chicago's Billy Goat Tavern to mark the departure of his spokesman, Lance Trover, for another job.
Kirk, 52, a Naval Reserve officer and former 10th District congressman, checked into Lake Forest Hospital on Saturday for treatment.
He had been en route to Chicago for a political event but asked his driver to divert to the hospital after experiencing symptoms, those close to him say.
At Lake Forest, doctors discovered a carotid artery dissection in the right side of his neck, in which a flap of tissue blocked the flow of blood in the carotid artery to the brain, Dr. Richard Fessler said Monday at a news conference at Northwestern Memorial Hospital.
Kirk was transferred to Northwestern Memorial on Sunday, where further tests revealed that he had suffered a stroke. Despite treatment, he was becoming less and less responsive, Fessler said.
"He was beginning to deteriorate neurologically, which is what forced our hand to go to surgery," Fessler said.
The stroke the Highland Park Republican suffered on the right side of his brain affected his left arm and possibly his leg, and it may "possibly involve some facial paralysis," Fessler said.
He said Kirk is fortunate the stroke did not occur on the left side of his brain, which deals with cognitive abilities, including the ability to speak, understand and think.
"We're very hopeful that when we get through all of this recovery, all of those functions will be intact and he should be able to do very well," Fessler said.
Recovery, including rehabilitation at an acute-care facility, is likely to take weeks or months. "It's not going to be days," Fessler said.
Fessler called it "not rare" for a 52-year-old man in good physical shape to suffer a stroke, but "not as common as (for) a 75-year-old person having a stroke."
Kirk has kept an unrelenting pace since announcing his campaign for the Senate from the steps of his childhood home in Kenilworth in July 2009.
After winning a hard-fought race against Chicago Democrat Alexi Giannoulias, he rushed headfirst into a six-year Senate term, marking his first year with trips to the Horn of Africa and Afghanistan. He returned from a four-day trip to Poland last week, a trip, the health-conscious senator joked, that caused him to gain 5 pounds.
In addition to his work as a senator, Kirk's naval duties led him to spend one weekend a month working at the Pentagon. And as the Illinois GOP's highest ranking officer, he is involved on a daily basis with helping coordinate the party's primary campaigns.
Friends often describe Kirk as a night owl and workhorse who will sometimes go all day before having a meal.
After Kirk's hospitalization over the weekend, his top staff was initially in a wait-and-see mode, keeping updates on his condition to themselves on Saturday and Sunday.
News first began to spread of the senator's condition early Monday morning.
Pat Brady, chairman of the Illinois Republican party -- who works closely with Kirk -- said he first heard the news from a reporter, who called him for comment about 9:45 a.m.
Kirk's chief of staff, Eric Elk, issued a statement later that morning.
Kirk, a bachelor divorced from his wife of eight years in 2009, has a number of family members who live in the area. In a statement, Kirk's family expressed thanks for the medical care and support he's received. "We are confident that the fighter in him will prevail," they wrote.
Fessler said he believes the functions Kirk requires to do his job as a senator "are going to be fine."
He said Kirk was already "responding to commands, and he seems to know the people around him."
The part of his skull that was removed can be put back in a few weeks, Fessler said.
Before his 2010 election to the Senate, Kirk served in the U.S. House for a decade, representing the North suburban 10th Congressional District in Cook and Lake counties, a seat now held by Congressman Bob Dold.
Shortly after news broke of Kirk's stroke, Illinois' other top Republicans began sending well-wishes, and both Twitter and Facebook were crowded with similar messages.
"My thoughts and prayers are with Sen. Kirk and his loved ones," U.S. Rep. Randy Hultgren of Winfield said in a statement. "I hope that he makes a complete and speedy recovery and quickly returns to serving the people of Illinois."
Illinois Comptroller Judy Baar Topinka called Kirk a "fighter."
"Like anyone who knows Sen. Kirk, I am stunned and saddened to hear about his recent stroke," she said in a statement. "But if there is one thing I have learned about Mark over the years, it's that he is a fighter and relentless in his efforts to accomplish a goal. Those attributes will serve him well in working toward a rapid recovery. My thoughts and prayers are with him."
U.S. Sen. Dick Durbin, a Springfield Democrat, noted Kirk had appeared to be the picture of health and said he wants Kirk to get well and get back to Washington as soon as possible.
Kirk, who has deep suburban ties, grew up in Kenilworth and graduated from New Trier High School. He won his first election at least in part by drawing on his experience working for former U.S. Rep. John Porter.
In subsequent campaigns and during his time in office, Kirk gained a reputation as a moderate Republican and often touted local projects as accomplishments, including efforts to clean up Waukegan Harbor.
Fessler called it "way too soon" to begin to speculate when Kirk might return to work.
In the meantime, the senator will remain in intensive care in a medically induced coma for the next several days, as doctors work to keep pressure on his brain "as low as we can."
• Daily Herald Staff writers Jake Griffin and Mike Riopell contributed.