An update on the Poison singer's condition was posted on his Web site Sunday.
"At this point Bret remains in ICU in critical condition. He is under 24 hour doctors care and supervision. We are hopeful that further tests will locate the source of the bleeding, which has still not been located. As we all know Bret is a fighter and we are hopeful that once all is complete the slurred speech, blurred vision and dizziness, etc., will be eliminated and all functions will return to normal," the post read.
The post also thanked Michaels' fans, who have expressed their concern since the news broke about the hemorrhage on Friday.
"Everyone at Michaels Entertainment would like to thank all fans and friends for their continued thoughts and prayers through this difficult time," it said.
A subarachnoid hemorrhage, which refers to the area of the brain where the bleeding occurs, "can happen to anybody at any time, and that's why it's scary," Dr. Keith Siller of New York University's Comprehensive Stroke Care Center told People. It is usually caused when an aneurysm, or enlarged artery in the brain, suddenly ruptures.
About half of such hemorrhages are fatal, Siller said, and 15 percent to 20 percent of sufferers never even make it to the hospital.
Siller told the magazine that neither Michaels' history with diabetes nor his recent appendectomy are triggers for this type of hemorrhage. His injury last year during a Tony Awards performance could not be the cause either, Siller said.
When the source of the bleeding is found, Siller said doctors will likely treat it with surgery, in which the source of the leak is clipped, or with "coiling," in which slivers of metal are inserted through a catheter in order to clot the blood.
Siller said the likelihood of Michaels' recovery depends on his condition when he was admitted to the hospital. "The better condition you are [in] when you get to the hospital - in other words, if you're awake, talking - if you're conscious, those people have a very good prognosis that they can come out of this OK," Siller said.