• Patient and/or legally authorized representative has agreed to participate in the study by signing the EC-approved consent form, where applicable.

• Patients (of any age) who underwent or who plan to have a surgical procedure utilizing one of the Codman CERTAS Plus Programmable Valves.

• Patient (legally designated representative) is willing to comply with the study protocol timelines \& requirements.

• For patients who have had the Codman CERTAS Plus Programmable Valve implanted prior to study enrollment, have available data from implantation to the current time.