This study collects exploratory data using a non-invasive device for assessing CSF shunt flow using thermal anisotropy measurements. Patients with an existing implanted ventricular CSF shunt will be enrolled into either a prospective (study device) or retrospective (no study device) cohort to gather data on health resource utilization, quality-of-life, and study device measurements.

Inclusion criteria

1. Existing ventricular cerebrospinal fluid shunt
2. Signed informed consent by subject or a parent, legal guardian, health care agent, or surrogate decision maker (according to local statutes)
3. Subject available for 2 week follow-up
4. Region of intact skin overlying an unambiguously identifiable palpable chronically indwelling ventricular shunt that crosses the clavicle; region of skin is appropriate in size for application of the study device (Cohort A only)

Exclusion Criteria

1. Presence of more than one distal shunt catheter in the study device measurement region
2. Presence of an interfering open wound or edema in the study device measurement region
3. Subject-reported history of serious adverse skin reactions to silicone-based adhesives
4. Participation in the study will interfere with, or be detrimental to, the administration of optimal health care to the subject