A burr cap assembly is at least partially inserted into a burr hole within the cranium of a patient. The burr cap assembly enables a elongate member to be inserted through the burr cap assembly to access a brain of the patient. A shifting member of the burr cap assembly may be configured to enable the elongate member to move with shifting fluid and matter of the brain. The shifting member of the burr cap assembly may be configured to move within a cavity defined by the burr cap assembly. The shifting member may be configured to move in a direction that is substantially perpendicular to a longitudinal axis of the distal portion of the elongate member. The shifting member may at least partially retain the elongate member, so as the shifting brain applies forces upon the elongate member, the elongate member and the shifting member may move within the cavity.