The authors present a noninvasive method of measurement of Intracranial pressure (ICP) . In this experiment, we aim to detect interference echoes originating from the dura including membranous structures of the subarachnoid space through the skulls of normal thickness. The result showed that interfering echoes could be received through a 2.4-5.0mm thickness of bone flap from the skull which was removed by craniotomy, when we used a probe with a diameter of 17-20mm. With our probes, we recorded ICP continuously by changing the head position, Valsalva's maneuver, and compressing the superficial temporal artery. This measurement was performed using two peak-detectors at from the same echo pattern. The changes in pulse waves of ICP were evaluated. From these results the authors confirm the usefulness in clinical applications of our noninvasive method for the ICP measurement.
