When U.S. Sen. Mark Kirk (R-Ill.) entered into a Chicago-area hospital after suffering a stroke in January, the senator used a fake name, presumably to keep his condition out of the public eye initially.

The Chicago Tribune reports that Kirk checked in at Lake Forest Hospital using the alias Hillel Underwood in order to "enhance his privacy" and to "reduce the chances of unwanted visitors during his medical crisis," according to a Kirk aide.

The senator had been suffering dizziness and headaches when he checked in to the hospital and doctors subsequently discovered a "carotid artery dissection." Kirk was transferred to Chicago's Northwestern Memorial Hospital where tests revealed he had suffered a stroke and he underwent emergency brain surgery.

Kirk, 52, is well on his way to recovery. In May, his office released a video detailing Kirk's work at the Rehabilitation Institute of Chicago, where he's working to regain his ability to walk and speak normally. He continues to be treated at the facility on an outpatient basis. Friends and colleagues of Kirk say the senator continues to have his eye on a return to being an active member of the U.S. Senate.

Meanwhile, another high-profile Illinois politician -- U.S. Rep. Jesse Jackson Jr. (D-Ill.) -- is on leave while he is being treated at an inpatient medical facility for "physical and emotional ailments." His office has not disclosed his location or provided any details of his medical condition.

The secrecy surrounding Jackson's condition has drawn the criticism of some of his constituents who say they deserve a less cryptic status update on their congressman.

"Who represents us?" Bishop Lance Davis of the New Zion Christian Fellowship in Dolton asked NBC Chicago. "And if he has a personal issue, then let us hear about it. Let us know what it is. We at least deserve that."

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  • In this series of three photos taken from video released Tuesday, May 8, 2012 by Sen. Mark Kirk's office, Kirk performs various walking exercises at the Rehabilitation Institute of Chicago following a stroke he suffered in January 2012. In the video, Kirk gives his first public remarks since suffering the stroke. On May 3, Senator Kirk was released from the RIC and moved home with his family. (AP Photo/Courtesy Sen. Mark Kirk's office)

  • This image taken from video and provided by Sen. Mark Kirk's office shows Sen. Mark Kirk, R-Ill. going through a walking exercise at the Rehabilitation Institute of Chicago following a stroke he suffered in January 2012. In the video, Kirk gives his first public remarks since suffering the stroke. On May 3, Kirk was released from the RIC and moved home with his family. (AP Photo/Courtesy of Sen. Mark Kirk's office)

  • This image taken from video and provided by Sen. Mark Kirk's office shows Sen. Mark Kirk, R-Ill. going through a walking exercise at the Rehabilitation Institute of Chicago following a stroke he suffered in January 2012. In the video, Kirk gives his first public remarks since suffering the stroke. On May 3, Kirk was released from the RIC and moved home with his family. (AP Photo/Courtesy of Sen. Mark Kirk's office)

  • This image taken from video and provided by Sen. Mark Kirk's office shows Sen. Mark Kirk, R-Ill. making his first remarks since suffering a stroke in January 2012 on Tuesday, May 8, 2012. Kirk says he can't wait to get back to work and is walking again. On May 3, Kirk was released from the Rehabilitation Institute of Chicago and moved home with his family. (AP Photo/Courtesy of Sen. Mark Kirk's office)

  • FILE - In this April 19, 2012 file photo provided by the Rehabilitation Institute of Chicago, Sen. Mark Kirk, R-Ill., talks with staff members at the Rehabilitation Institute of Chicago, in the first public image of Kirk since he suffered a stroke in January 2012. On Thursday, May 3, 2012, Kirk's office released a statement saying the 52-year-old senator has been released from the rehabilitation center and recovered to the point where he can move home with his family. (AP Photo/Rehabilitation Institute of Chicago, File)

  • Dr. Richard Fessler, a neurosurgeon at Northwestern Memorial Hospital updates the media on U.S. Sen. Mark Kirk's condition since suffering a stroke over the weekend, Tuesday, Jan. 24, 2012, in Chicago. Fessler says the Illinois Republican has some facial paralysis and speaks with a slight slur, but is answering questions and is very aware of his surroundings. The doctor says Kirk appears eager to get back to work and has asked for his Blackberry. (AP Photo/M. Spencer Green)

  • FILE - In this Wednesday, Feb. 2, 2011 photo, Sen. Mark Kirk, R-Ill. leaves a Republican caucus on Capitol Hill in Washington. When a stroke hits at 52, like what happened to Sen. Kirk, the reaction is an astonished, "But he's so young." The reality is that strokes can happen at any age, even to children - and they're on the rise among the young and middle-aged. The vast majority of strokes do occur in older adults. But up to a quarter of them strike people younger than 65, says Dr. Ralph Sacco, a University of Miami neurologist and past president of the American Heart Association. (AP Photo/Manuel Balce Ceneta)

  • Dr. Richard Fessler, a neurosurgeon at Northwestern Memorial Hospital who performed surgery on U.S. Sen. Mark Kirk, R-Ill. after he suffered a stroke, arrives to answer questions about the Senator's conditions at a news conference, Monday, Jan. 23, 2012, in Chicago. Kirk, 52, checked himself into Lake Forest Hospital over the weekend before being transferred to Northwestern Memorial Hospital in Chicago, where tests showed he had suffered a stroke. Kirk's office said he had a tear in the carotid artery on the right side of his neck. Carotid arteries carry blood to the brain; carotid tears are a common cause of strokes, which can involve blood clots traveling to the brain and causing bleeding there. The surgery was performed Sunday night. (AP Photo/M. Spencer Green)

  • In this Nov. 1, 2010 photo, U.S. Sen. Mark Kirk, R-Ill., looks to a crowd of supporters during a campaign rally in Wheaton, Ill. A spokesperson for Sen. Mark Kirk says the Illinois Republican has suffered a stroke and has undergone surgery early Monday, Jan. 23 2012 to relieve swelling around his brain. The 51-year-old Kirk checked himself into Lake Forest Hospital in Illinois. He was later transferred to Northwestern Memorial Hospital in Chicago, where tests showed that he had suffered a stroke. (AP Photo/Nam Y. Huh, File)