Algorithm for troubleshooting external ventricular drain (EVD) blockage. CSF, cerebrospinal fluid; NS, normal saline; CT, computed tomography; EVD, external ventricular drain. Source: External Ventricular Drain Management and Ventriculoperitoneal Shunts, The NeuroICU Book, 2e Citation: Lee K. The NeuroICU Book, 2e; 2017 Available at: https://neurology.mhmedical.com/DownloadImage.aspx?image=/data/books/2155/leeneuro2_ch22_f008-2.png&sec=163965041&BookID=2155&ChapterSecID=163964998&imagename= Accessed: October 12, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved