Stroke Treatment -- Regional Variation (image) University of Michigan Health System Share Print E-Mail Caption This map of the 3,426 hospital service areas in the continental US shows rates of tPA use for emergency care, from highest (green and blue) to lowest (yellow, orange and red). Areas in black had fewer than 50 strokes a year. Credit University of Michigan Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.