1 If a lot of blood leaks out, it can cause a buildup of pressure in the brain because the brain is enclosed in the skull. There is no room for brain tissue to expand, and so the leaked blood can compress and kill important areas of the brain.  Hemorrhagic strokes tend to be more serious than ischemic strokes.
Horizontal definition, at right angles to the vertical; parallel to level ground. See more.
horizontal. 1  at right angles to the vertical; parallel to level ground. 2  flat or level: a horizontal position. 3  being in a prone or supine position; recumbent: His bad back has kept him horizontal for a week. 4  near, on, or parallel to the horizon. 5  of or relating to the horizon.