On August 31st, 2007, then 27-year-old Marissa Kristal was running on a treadmill when the most excruciating pain she ever felt struck her in back of her head and immediately washed over her entire skull. She was certain she was having an aneurysm. Mercifully, she was wrong. Marissa suffered a subarachnoid hemorrhage (SAH). This means a vein in her brain burst. When a person suffers a SAH the cerebrospinal fluid in the subarachnoid space becomes bloody - a very dangerous and often life-threatening occurrence. Sufferers tend to experience "the worst headache of their lives." The pain is sudden...