Bret Michaels has suffered a setback on the road to his recovery from a brain hemorrhage last week.
While doctors have told ABC News that a "full recovery" may still be possible for the rocker and reality star, he has experienced a side effect called hyponatremia, a lack of sodium in the body which could lead to seizures.
The former Poison frontman, 47, remains in intensive care and is said to be in critical, but stable condition.
The setback comes after Michaels' publicist confirmed last week that Michaels had suffered a massive subarachnoid hemorrhage, or bleeding at the base of his brain stem. On Sunday, statements posted on the star's official website indicated that he was still in the intensive care unit at an undisclosed hospital and in critical condition. The statements also indicated that doctors had not yet located the source of the bleeding in his brain.
Doctors have yet to detail exactly what caused the bleeding in the first place. However, some neurologists were optimistic that Michaels would survive the ordeal -- although the recovery process could take several several weeks to months. In a bit of hopeful news, Michaels' father reported that his son was able to talk on Friday, albeit with slurred speech.
He was also reportedly experiencing blurred vision.
"The long-term prognosis from subarachnoid hemorrhage depends mostly on how poor the patient's condition was on arrival," said Dr. Wendy Wright, an assistant professor of neurology and neurosurgery at Emory University Hospital in Atlanta. "We do know that Mr. Michaels' condition is still being described as critical; that is an automatic label for anyone who is diagnosed with subarachnoid hemorrhage, due to the severe, life-threatening nature of this disease. However, the fact that he is conscious does suggest a better prognosis than if he were comatose.
"Based on how he is being described now, I would like to remain optimistic that he will survive this potentially devastating diagnosis."
"The fact that he's made it to a hospital and is apparently in some sort of reasonable condition... that's a good sign." Said Dr. Arno Fried, chairman of Neurosurgery at Hackensack University Medical Center in Hackensack, N.J. "I would describe [Michaels' condition] as guarded. If the bleed has not caused too much damage, the possibility of recovery is quite good."
Dr. Daniel Barrow, who is chairman neurosurgery at Emory University Hospital, agreed that the latest reports suggest that Michaels' condition could be far worse.
"If he is hospitalized and speaking, he is in a much, much better category with regard to the possibility of a good recovery," Barrow said. "The best outcome is that he will be able to resume all of his previous activities with no complications. That is conceivable."
But, Barrow said, "There are many hurdles to cross before [Michaels] is out of the woods."
Part of determining exactly what these hurdles are depends on doctors' ability to determine the nature of the bleeding. Neurologists have said an aneurysm -- a balloon-like bulge in an artery that has the potential to rupture -- is a possible cause.