Systems and methods for monitoring physiological parameters such as intracranial pressure (“ICP”), intracranial temperature, and subject head position are provided. 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. The ports may also be configured such that a barrier is not necessary. Standoffs on the body may be included that stabilize the implant on the skull and enhance reliability and robustness of the measurements.
