Bret Michaels suffered a 'warning stroke' and returned to hospital.Bret Michaels suffered a 'warning stroke' and returned to hospital. (Jason Merritt/Getty Images)

Bret Michaels, the rocker and reality TV star, is back in hospital after suffering what doctors call a "warning stroke," his website reported.

The former Poison frontman has been diagnosed with patent foramen ovale, an incomplete closure of the wall between the two upper chambers of the heart, the website reported. His publicist, Joann Mignano, confirmed the report.

Michaels was hospitalized after experiencing numbness on the left side of his body, particularly in his face and hands.

Doctors say the condition is operable and treatable, and likely unrelated to the brain hemorrhage the 47-year-old suffered last month.

His neurosurgeon said Michaels has a "fantastic attitude" about making a full recovery, "Bret's brain and body are not quite 100 per cent yet, especially with the hole found in his heart."

Additional tests were being conducted to determine the best course of treatment.

Doctors said Michaels is being treated with a daily injection of a blood thinner to reduce the risk of clots.

The website said he was "up, walking, talking, continuing his daily rehab and very happy to be alive."

"He has made it clear he is sick and tired of being in the hospital and is ready to rock again," the site says.

However, his expected appearance in New York at Sunday's finale of Donald Trump's The Celebrity Apprentice was in doubt.