I saw that Sen. Tim Johnson had some stroke like symptoms late yesterday afternoon.  Only this morning did I truly understand the importance of the event.  As a surgeon, I really don’t have any great insight yet.  There simply isn’t enough information.  Brain surgery, for what?  A tumor?  A bleed?  An aneurysm?  Depending on the etiology the prognosis is different.  We’ll have to wait until later on in the day when information is available.

From CNN.com:

Sen. Tim Johnson of South Dakota underwent brain surgery early Thursday at George Washington University Hospital after suffering stroke-like symptoms, two Democratic sources familiar with his condition told CNN.

Johnson, 59, was taken to the hospital Wednesday after he appeared to suffer the stroke-like symptoms, although a spokeswoman for the senator said subsequent evaluation showed he did not suffer a stroke or a heart attack.

There was no word early Thursday on the nature of Johnson’s surgery or his condition.

Staffers told CNN that Johnson was conscious when he was transported to the hospital.

Senate Minority Leader Harry Reid, D-Nevada, spent time at the hospital out of concern for Johnson, Reid’s spokesman said.

Johnson spokeswoman Julianne Fisher said the senator was in the Capitol on Wednesday morning conducting a conference call with South Dakota reporters when “his speech pattern slipped off.”

Fisher said the senator was able to walk back to his office in the Hart Senate Office Building, then began having problems with his right arm. He thought he was all right, she said, and went to his desk, but came out a few minutes later and “it was apparent he needed help.”

Staffers put him on a couch in the office and called the Capitol doctor, she said. He was taken to the hospital shortly afterward. His wife, in the office to have lunch with him, rode with him, Fisher said.

“It transpired very fast,” she said, adding the senator’s staff was shaken by the incident.

But, she said of the hospital, “we keep reminding ourselves, this is where they take Dick Cheney.”

Should Johnson not be able to complete his term, which ends in 2008, South Dakota Gov. Mike Rounds, a Republican, could appoint his replacement, which could shift the balance of power in the Senate.

South Dakota Secretary of State Chris Nelson said the appointment would fill the vacancy until a general election could be held in November 2008. There are no restrictions on who the governor can appoint, beyond meeting the legal requirements for Senate membership, he said.

Although the issue of incapacitation is not spelled out in state law, Nelson said he believes there would be “precedent at the federal level.”

South Dakota has not faced the replacement of an elected office holder “in recent history.”

Rounds issued a statement saying his prayers were with Johnson and his family. “We are hopeful of good news for our friend and colleague,” the governor said.

Johnson battled prostate cancer in 2004, and after surgery, tests showed he no longer had the disease, according to his Web site.