An "intercranial hemorrhage," meaning bleeding inside his brain or, as we non-medicos would call it, a stroke. Early reports on this story were that he fell, but whether he fell due the stroke or the bleeding was a result of his fall, I don't know.
Yeah, I read he had a couple of seizures earlier this year too, he may have had another seizure which caused the fall. He had heart problems recently as well. He must have been in failing health. 42 is young, but with 2 kidney transplants, I suspect he was living on borrowed time. God bless him.