31.   Gray said he believed the stroke was caused by a blood clot.

32.   Gullikson, the twin brother of U.S. Davis Cup captain Tom Gullikson, returned home during the Australian Open in January because of brain tumors that caused three strokes.

33.   It is impossible to tell without seeing a doctor what caused a stroke, Furie said.

34.   Last year, Martins was hit over the head during a mugging in Bulgaria, which caused a stroke affecting his right side.

35.   Once at a hospital, doctors must make sure the stroke is actually caused by a clot in the brain.

36.   Strokes are caused by the rupture or blockage of a blood vessel or artery in the brain.

37.   Strokes are occasionally caused by a burst blood vessel.

38.   Then researchers discovered that TPA, or tissue plasminogen activator, already the mainstay of treating heart attacks, could also dissolve the blood clots that cause most strokes.

39.   They normally are given a blood thinner called heparin to prevent clots, which can cause a stroke by traveling to the brain.

40.   Doctors said his strong workout had caused a stroke.