Your brain is suspended in a liquid called craniosacral fluid CSF. The brain is held in place by membranes called dura. They connect with a long sheath that protects the spinal chord called the dura mater (Latin: tough mother) The dura mater is attached from the top of the neck to the base of the spine called the sacrum (sacred bone, seat of emotion). CSF is a straw coloured fluid produced by tiny blood vessels inside the skull. About half a litre a day flows into the dural cavity. It feeds and protects the nerves, flowing down around the spinal chord in a slow spiral motion. A trained person can, with practice, detect a subtle change of pressure in the rhythm of the CSF. It appears as if the head changes shape, slowly widening then pausing then narrowing. In practice the pressure is changing. The fluid is produced roughly for six seconds then switches off for six seconds. The sensation can be felt in many parts of the body, for instance the feet appear to rotate outwards then inwards again.
Many factors can alter the rhythm of the CSF for instance, birthing trauma, a series of head injuries, a fall onto the coccyx, a fast ride on a roller coaster or lift, anxiety combined with loss of a sense of the horizon in a large swell at sea, inflammation of the meninges, chronic post viral fatigue, sepsis are all conditions that I have come across.
Treatment with craniosacral therapy
Listening is the most important. cradling the head in your hands with your fingers placed on key points.