Physiological Mechanisms Underlying the Primary Respiratory Mechanism (PRM) and Cranial Rhythmic Impulse (CRI) in Osteopathy: A Systematic Review.

Background: Cranial Rhythmic Impulse (CRI) or Primary Respiratory Mechanism (PRM), movement felt on the scalp or the rest of the body, respectively, is a fundamental concept used by osteopaths in their practice for their diagnosis and treatment. However, the physiological basis of this phenomenon remains unclear. Sutherland, the founder of cranial osteopathy, proposed in 1939 that PRM was due to the movement of the cranial bones pulled by the meninges, themselves pushed by the fluctuation of cerebrospinal fluid and the motility of the central nervous system.