Abstract: A sensor attaching device and a method for monitoring physiological pressure and other physiological parameters by application of an external pressure sensor to the surface of the brain is disclosed. The cranial sensor attaching device consists of a series of concentric cylinders, two of which have flanged ends configured in such manner that the flanged end of the outer cylinder expands radially when the flanged end of the inner cylinder is withdrawn through it. This feature prevents the device, once inserted through a hole in the skull, from being withdrawn. The flange on the outer cylinder is configured so that when inserted and expanded it contacts the inner lip (table) of the skull at three equidistant points around the circumference of the hole, thus assuring that the tip of the sensor is positioned tangential to the surface of the brain.