Prime Minister Ariel Sharon was suffering from an undiagnosed vascular brain disorder that can be worsened by the blood thinners he was taking before his massive stroke last week, the Haaretz newspaper reported Tuesday. If the disease of the blood vessels in the brain had been diagnosed when Sharon suffered a first stroke on December 18, doctors most certainly would have not prescribed the blood thinners due to the risks, a senior doctor treating Sharon told Haaretz. The ailment was discovered only after Sharon suffered a massive stroke last week, the paper said. Sharon's brain disorder is called cerebral amyloid angiopathy, which is diagnosed by brain scans. Sometimes it can be detected only after brain hemorrhaging, the daily said. Hospital spokeswoman Yael Bossem Levy declined to comment on the report. "We are busy treating the prime minister and fighting for his life and nothing else," she said.