Functional and Non-Functional CSF Shunt Flow Measured With a Second-Generation Wireless Thermal Device

Inclusion Criteria: 1. At least one existing ventricular CSF shunt, functional or non-functional (including an adjustable valve set to "virtual off," ligated shunt, uncorrected distal catheter disconnection or fracture, distal catheter fragment left in place during shunt surgery, or indication that the shunt is otherwise non-functional), with a region of overlying intact skin appropriate in size for application of the study device 2. If more than one distal shunt catheter is present, at least one distal shunt catheter is at least 2 cm away from any other distal shunt catheter in the device measurement region 3. Signed informed consent by subject or a parent, legal guardian, health care agent, or surrogate decision maker (according to local statutes) 4. Signed medical records release by subject or a parent, legal guardian, health care agent, or surrogate decision maker (according to local statutes) 5. Verbal assent by minors 7 years of age and older who are able to understand the study and communicate their decision Exclusion Criteria: 1. Presence of an interfering open wound or edema in the FlowSense device measurement area 2. Patient-reported history of adverse skin reactions to adhesives 3. Previous participation in a Rhaeos clinical study in which FlowSense device measurement data were acquired 4. New or worsening symptoms of a possible shunt malfunction in the prior 7 days 5. Use of the study device would interfere with standard patient care, or emergency surgery that cannot be delayed, or participation in the study will interfere with, or be detrimental to, administration of optimal healthcare to the subject 6. Participation in any other investigational procedural, pharmaceutical, and/or device study that may influence the collection of valid data under this study