The invention provides a catheter comprising an elongate body having an exterior surface with a substantially planar portion, a perforation that extends through the planar exterior surface to an internal lumen, providing fluid communication between the lumen and said surface, and a movable covering to occlude the perforation when the catheter body is moved relative to brain tissue during insertion and withdrawal from said tissue. The invention extends to a method of removing excess cerebrospinal fluid from a patient through use of the catheter. The coverings fold according to the direction of movement to cover an adjacent trailing perforation against ingress of tissue fragments.
