To describe the natural history of a condition or disease. To describe the natural history of a condition or disease. To determine effectiveness or cost effectiveness of treatments/services and/or health care products. To measure or monitor safety and harm. To measure quality of care.
According to the NMSS, attacks or flare-ups of symptoms only qualify as exacerbations if: 1  they occur at least 30 days from an earlier flare-up. 2  symptoms last for 24 hours or longer.
Introduction. Transient ischemic attacks (TIAs), sometimes called mini-strokes, happen when a blood clot temporarily reduces blood flow to the brain. Symptoms usually last only 10 to 15 minutes and clear up within 24 hours, with no lasting damage. But having a TIA puts you at risk for a stroke.