1. An implantable system, comprising: a) an electrode subsystem configured to interface with biological tissue; b) an electronic subsystem electrically coupled to the electrode subsystem by a connector; and c) a guide tube disposed over at least a portion of the electrode subsystem and at least a portion of the connector, the guide tube having a length extending in an axial direction and a width extending in a radial direction, wherein the guide tube comprises an anisotropic material that is rigid in the axial direction and expandable in the radial direction; d) at least one spiral spline removably disposed longitudinally in the guide tube, the at least one spline being rigid in the axial direction and flexible in the radial direction of the guide tube to thereby provide stiffness to the electrode subsystem and to the connector in the axial direction of the guide tube, e) wherein the guide tube is removable from the electrode subsystem, the connector, and the electronic subsystem with the guide tube remaining cohesive during such removal.