Updated

Argentina's presidential spokesman says Cristina Fernandez is in good spirits following successful surgery to remove fluid from the surface of her brain after she suffered an unexplained head injury over the summer.

Alfredo Scoccimarro said Tuesday that Fernandez, 60, is recovering in her hospital room and has thanked her doctors as well as supporters gathered outside who have been praying for her.

Scoccimarro said "the operation went very well" and that the next announcement about her health will come at midday Wednesday.

Hospital doctors report that the Fernandez's condition is "evolving favorably" after they removed a blot clot pressuring the right side of her brain.

Buenos Aires Gov. Daniel Scioli said Fernandez is recovering from anesthesia inside the Fundacion Favaloro, one of Argentina's top cardiology hospitals.

"We have received first word that the president has come out of surgery and is recovering from anesthesia," Scioli announced earlier Tuesday.

Fernandez's condition is described as a subdural hematoma. The Los Angeles Times reported that she had complained of headaches and experienced tingling in her left arm.

"If she felt some sensory disorders, the haematoma has expanded and is pressing on the brain," Alejandro Andersson, director of the Neurological Institute of Buenos Aires, who isn't treating Fernandez, told Bloomberg Businessweek. "The surgery shouldn't last more than an hour. Doctors have quick access to the clot, they remove it and patients usually recover 100 percent."

The surgery involves drilling small holes through the skull. In a three-paragraph statement, her doctors attributed the injury to a still unexplained blow to her head that she suffered on August 12. That would have been the day after a primary vote showed a significant drop in support for ruling party candidates, despite her intensive campaigning.

Vice President Amado Boudou made no mention of the planned operation. He said in a speech that top officials would run the country as a team "while she gets the rest she deserves."

What he didn't say — and no other official ventured to guess — was whether Fernandez will formally delegate her executive powers during the surgery, or while she recovers. Boudou is under investigation for alleged corruption and illegal enrichment and currently has one of the worst images among Argentine politicians.

Even Sen. Anibal Fernandez, who often acts as a government spokesman, told the Telefe channel earlier Monday that "We don't have clear idea what will happen."

The Saturday night statement, read by her spokesman Alfredo Scoccimarro after she had spent nine hours in the hospital, provided no more details about the accident or the injury it caused. Questions left with Scoccimarro by The Associated Press were not immediately answered.

It's not unusual for symptoms of a chronic subdural hematoma to take weeks to appear, and many patients don't even recall injuring their heads, according to the Mayo Clinic in the United States.

But the surgery is considered to be low-risk, and the symptoms can be effectively and safely treated by draining the blood mass through a catheter, according to guidance from the University of Los Angeles.

Argentina's constitution provides for, but does not require, a formal transfer of power in case of health problems, said Daniel Sabsay, a constitutional lawyer. A full medical leave would require congressional approval, but short of that, "she alone decides, according to the problem she faces and her doctors' advice, if she needs to delegate some powers to the vice president," he told Radio Continental.

The Associated Press contributed to this report