April 23, 2010 -- Over the course of a few days, Bret Michaels went from rocking reality TV to reeling from health problems.
The ex-Poison frontman, former star of VH1's "Rock of Love With Bret Michaels," and current "Celebrity Apprentice" contestant was hospitalized at an undisclosed facility Thursday after suffering a massive subarachnoid hemorrhage, or bleeding at the base of his brain stem, his publicist confirmed to ABCNews.com.
Michaels, 47, was in critical condition and under "intense observation" by doctors while they run tests to determine the cause of his bleeding, People magazine reported.
Last weekend, Michaels revealed to his fans that he was rushed to a hospital on April 11 for an emergency appendectomy.
"They told me that if I had gone onstage like I wanted to, [my appendix] likely would have ruptured and I could have died," he wrote on his blog.
Michaels was scheduled to perform in San Antonio, Texas that night.
"I'm feeling pretty bad ... to tell you the truth," Michaels wrote after the appendectomy. "When you're not planning on having a body part ripped out of you, it can be a shock to the system. While the doctors are amazing in San Antonio, there is just no way around the fact that getting your appendix out HURTS. I have a pretty good threshold for pain, but this one hurts."
The rocker added that because he's been a diabetic since age 6, his recovery could take longer than usual. However, it's unlikely that Michaels' diabetes spurred his current condition.
"This [type of hemorrhage] is usually from an anueursym," Dr. Wendy Wright, an assistant professor of neurology and neurosurgery at Emory University Hospital in Atlanta, told ABCNews.com. "The risk of an aneurysm rupturing is probably related to size -- the larger the aneurysm, the more likely to rupture -- and also may be more likely in people who smoke or on blood thinning medications."
A factor that could have played into Michaels' current condition is his past history of drug use. Michaels hasn't been shy about his hard-partying, rock and roll past. In a 2003 interview with VH1, he described a "menage a mess" from his Poison days, saying, "It was the drugs, the booze, doing the lines off [exotic dancers]."
"Being a drug user, in particular a user of injectable drugs, can damage heart valves and predispose you to get endocarditis," said Dr. Richard Bernstein, a neurologist at Northwestern Memorial Hospital.
Endocarditis involves infection at one of the heart's valves.
Bernstein added: "Cocaine use in and of itself can be a major cause of intracerebral hemorrhage."
ABC News' Dan Childs contributed to this report.