Updated at 3:52 p.m.

The neurosurgeon who operated on Illinois U.S. Sen. Mark Kirk following a stroke this weekend said the senator is “doing better than [the doctor] expected he would be doing at this point.”

Dr. Richard Fessler of Northwestern Memorial Hospital said Kirk is mildly sedated and breathing on his own.

“He’s answering questions appropriately and very quickly, so mentally he’s doing very well,” Fessler said in a Tuesday press conference.

Those answers range from a few words to longer sentences, depending on how sedated Kirk is at the time. Fessler said Kirk is slurring his speech because of “slight facial paralysis on the left side.”

“With therapy that usually gets better,” Fessler added.

Fessler said the left side of Kirk’s body is moving “very little,” the result of the ischemic stroke, which deprived portions of the right side of his brain of blood.

The doctor said Kirk has not mentioned his Senate duties at all, though he did ask for his Blackberry, a request Fessler said he denied.

When Fessler told Kirk he’d had a stroke, the senator displayed “really no distinguishing response,” the doctor said.

Asked whether memory functions could have been affected by the stroke, Fessler said, “Possibly, and those we won’t know until he’s fully recovered.”

Fessler had no answer for the cause of the carotid artery dissection in Kirk’s neck that led to the stroke.

“I don’t think that this event had anything to do with either stress or his diet. It was just one of those unfortunate disasters that happen to people sometimes,” Fessler said.

Ex-wife’s comments

The question of diet and exercise arose after comments Kirk’s ex-wife made to Chicago Magazine. Kimberly Vertolli said during their marriage Kirk had a “terrible diet” and rarely exercised.

But Fessler pointed out to reporters Tuesday that Kirk, a commander in the Naval Reserves, “had to pass his Navy physical twice a year. He’s got to be in reasonably good shape.”

“To my knowledge, his lifestyle is the lifestyle of a normal, healthy person who works out and eats a reasonable diet and takes care of themselves,” Fessler said.

Fessler had not treated Kirk prior to the stroke, but said he has served on Kirk’s health care policy committee. Campaign finance records also show that Fessler is a longtime supporter of Kirk’s campaigns, donating $14,800 since 2003.

The symptoms begin

Kirk first complained of symptoms on Saturday in the early afternoon.

“He text-messaged me to tell me he was having some symptoms,” said Kirk’s primary care physician, Dr. Jay Alexander, in a phone interview Tuesday afternoon.

Alexander, who is a cardiologist, said he got the message at 12:28 p.m. on Saturday and called Kirk back. Kirk described symptoms including odd “sensations” in his left arm and leg, feeling faint, headache and seeing white dots.

“He kept telling me it was like a snow storm,” Alexander recalled.

Kirk was a passenger in a car headed to Chicago for a meeting of his Eastern European advisory board. Alexander said he told Kirk to turn around and come to Lake Forest Hospital, where the doctor was working on Saturday. When Kirk arrived at the emergency room, “nothing was obvious…He was neurologically intact.”

Still, Alexander said, “He didn’t look right.”

Kirk underwent a CT scan of his head and a CT angiogram of his carotid arteries. At that point, around 2 or 2:30 p.m., doctors discovered a right internal carotid artery dissection. The artery, Alexander said, “appeared to be fully blocked.”

Kirk was admitted to Lake Forest Hospital, put on bed rest and the blood thinner heparin. Alexander said many of the symptoms had subsided by then, except for a “dull headache.” But around 9 p.m., Kirk started having “waxing and waning” neurological symptoms “that suggested an impending stroke.”

Before midnight, Alexander said he rode with Kirk in an ambulance to Northwestern Memorial in Chicago, and stayed with him until Sunday morning. Alexander has visited since to offer support for Kirk’s family, though he is not part of the team now treating the senator.

“We’ve been friends since he entered Congress,” Alexander said. “I’m sad. I’m nervous for him. I’m very optimistic.”