Abstract: A method to measure effective cerebral outflow pressure or intracranial pressure is disclosed. The craniospinal venous system has multiple anastomoses between the jugular veins and vertebral venous plexus. Jugular veins collapse with cervical compression or head elevation, when extrinsic pressure exceeds venous pressure. The vertebral venous plexus is exposed to intracranial pressure and collapses when intracranial pressure exceeds venous pressure. Vertebral venous plexus is not compressed with head elevation or cervical compression, because enclosure in the spinal canal protects veins from the direct effects of atmospheric pressure and cervical compression. Using cervical compression and/or head elevation blood outflow is redistributed between jugular veins and vertebral venous plexus, while the degree of cervical compression or head elevation indicates effective cerebral outflow pressure or ICP.