An adjustable drainage system for regulating cerebrospinal fluid flow in a hydrocephalus patient where the drainage rate is adjusted in response to ventricular volume variations in the patient. The system includes an adjustable valve and a volume sensor that can be periodically energized with an external system controller device by the patient or attending physician to determine when, or if, a change in the ventricular volume has occurred. The system enables the user to adjust the valves resistance in response to changes in the ventricular volume using the controller device so that a target ventricular volume can be achieved. Also provided is a method of continuously draining cerebrospinal fluid from the cranial cavity of the patient using the system of the present invention.
