Some embodiments of the present disclosure comprise improved systems and methods for monitoring physiological parameters such as intracranial pressure (&ldquoICP&rdquo), intracranial temperature, and subject head position. For example, in some embodiments, an implantable apparatus for measuring ICP can be implanted into a subject skull. The apparatus can comprise an implant body having a hermetically sealed chamber housing a gas at a reference pressure, and a pressure conduction catheter having a proximal end and a distal end, wherein the distal end is configured to extend into the brain through a burr hole in the skull and includes a plurality of ports. A barrier can cover the ports of the distal end of the pressure conduction catheter, wherein the barrier and pressure conduction catheter are filled with a number of gas molecules so that the barrier is not in tension in a predefined range of ICPs.
